WO2019161049A1 - FABRICATION OF NON-ENZYMATIC SENSOR BASED ON Pt/PVF OR Au/PVF OR Ir/ PVF ON A MODIFIED Pt ELECTRODE FOR DETERMINATION OF GLUCOSE - Google Patents

Abstract

A non-enzymatic glucose sensor was fabricated by immobilization of platinum (Pt), gold (Au), or iridium (Ir) particles on a redox polymer on a Pt electrode. Specifically, Pt or Au, particles were electrodeposited on polyvinylferrocenium (PVF⁺) matrix from a K₂PtCl₆ or KAuCl₄ solution followed by electrochemical reduction of the Pt or Au particles. Alternatively, Ir particles may also be electrodeposited on polyvinylferrocenium (PVF⁺) matrix followed by electrochemical reduction of the Ir particles. The as-prepared Pt/PVF or Au/PVF or lR/PVF modified Pt electrode provides a non-enzymatic glucose sensor characterized by one or more qualities of improved sensitivity, high selectivity, stability, fast response, and reproducibility. The applicability of the proposed sensor was confirmed from the successful determination of glucose concentration in various juice samples.

Description

FABRICATION OF NON-ENZYMATIC SENSOR BASED ON Pt/PVF OR An/ PVF OR Ir/PVF ON A MODIFIED Pt ELECTRODE FOR DETERMINATION OF GLUCOSE

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S . Provisional Application No.

62/630,464, filed February 14, 2018, and U.S. Provisional Application No. 62/634,295, filed February 23, 2018, both of which are hereby incorporated by reference.

STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT

[0002] Not applicable.

FIELD OF THE INVENTION

[0003] The present invention relates to a non-enzymatic glucose sensor fabricated by immobilization of platinum (Pt), gold (Au), or iridium (Ir) particles on a redox polymer (e.g., polyvinyl ferrocene matrix (PVF)) electrodeposited on a Pt electrode. The prepared Pt/PVF, Au/PVF, or Ir/PVF modified Pt electrode has improved sensitivity, high selectivity, stability, fast response, and low cost.

BACKGROUND OF THE INVENTION

[0004] The need for detection of glucose is not limited to the field of clinical diagnostics but is also applicable to biotechnology, pharmaceuticals, as well as the food industry. This ongoing demand has led to the continuous research in the development of stable, low cost, and fast response glucose sensors.

[0005] Amperometric glucose sensors have been classified as either enzymatic or non- enzymatic-based glucose sensors. Research in the field of enzymatic-based glucose sensors has led to the development of improved glucose sensors in terms of stability, sensitivity, selectivity, detection limits, and cost. However, the major challenge with enzyme-based glucose sensors is that the enzymes routinely lose their activity due to variation in temperature, humidity, and pH.

[0006] Problems of current glucose detection products are caused by the nature of enzymes: (1) enzymes are very active so that careful storage and maintenance are required and (2) enzymes are sensitive to the change of environment, therefore, the products are not suitable for harsh conditions such as acidic objects.

[0007] In order to overcome these drawbacks, recent research has focused on

development of non-enzymatic glucose sensors that avoid the drawbacks of enzymatic designs.

SUMMARY OF THE INVENTION

[0008] According to one aspect of the present invention, a method of fabricating a non- enzymatic glucose sensor has been developed including the following steps: (a) electrodepositing a redox polymer film on a substrate electrode; (b) electrodepositing noble metal particles to abide on the redox polymer film; and (c) electrochemically reducing the noble metal particles on the redox polymer film; wherein a non-enzymatic glucose sensor is provided that yields an amperometric response to a glucose concentration contacted with the non-enzymatic glucose sensor.

[0009] The redox polymer film may be an oxidized polyvinyl ferrocene (PVF⁺), the substrate electrode may be a platinum (Pt) substrate electrode, and the noble metal may be at least one of a platinum (Pt), gold (Au), and iridium (Ir).

[0010] Electrodepositing the Pt substrate electrode with the PVF⁺ may take place in a dichloromethane (CH2CI2) solution.

[0011] The method may further comprise the step of electro-oxidizing PVF to PVF⁺ wherein the electro-oxidizing step is approximately 180 seconds in duration.

[0012] The method may further comprise the step of forming polyvinylferrocenium ion perchlorate (PVF⁺C104"); and electro-precipitating the PVF⁺ClO₄- on the Pt substrate electrode.

[0013] The Pt may be electrodeposited on the PVF⁺ polymer film by submerging the

PVF⁺ polymer film with K₂PtCl₆ in HC1 solution.

[0014] The concentration of the K₂PtCl₆ may be 2.0 mM.

[0015] The Pt may be electrodeposited on the PVF⁺ polymer film by cyclic voltammetry (CV) scan.

[0016] The CV scan may be at about 50mVs^-1 scan rate for 30 cycles. [0017] The Pt may be electrodeposited on the PVF polymer film by an applied potential of about 0.2 V.

[0018] The electrochemical reduction of Pt particles may be from a Pt(IV) oxidation state to a Pt(II) or Pt(0) oxidation state.

[0019] The electrochemical reduction may occur in H2SO4 solution.

[0020] The Au may be electrodeposited on the PVF⁺ polymer film by submerging the

PVF⁺ polymer film with KAuCl₄ in HC1 solution.

[0021] According to another aspect of the present invention, a non-enzymatic glucose sensor for detecting a concentration level of glucose includes a platinum (Pt) substrate electrode; a Polyvinyl ferrocene (PVF⁺) polymer matrix coating the Pt substrate electrode; and a plurality of Pt particles electrochemically deposited on the PVF⁺ matrix; wherein the non-enzymatic glucose sensor is fabricated according to the method described above.

[0022] According to another aspect of the present invention, a non-enzymatic glucose sensor for detecting a concentration level of glucose includes a platinum (Pt) substrate electrode; a Polyvinyl ferrocene (PVF⁺) polymer matrix coating the Pt substrate electrode; and a plurality of Iridium (Ir) particles electrochemically deposited on the PVF⁺ matrix; wherein the non- enzymatic glucose sensor is fabricated according to the method described above.

[0023] According to another aspect of the present invention, a non-enzymatic glucose sensor for detecting a concentration level of glucose includes a platinum (Pt) substrate electrode; a Polyvinyl ferrocene (PVF*) polymer matrix coating the Pt substrate electrode; and a plurality of gold (Au) particles electrochemically deposited on the PVF⁺ matrix; wherein the non- enzymatic glucose sensor is fabricated according to the method described above.

[0024] According to another aspect of the present invention, a method of detecting a glucose concentration level in a sample includes the following steps: contacting a glucose sensor fabricated according to the method described above with a glucose-containing sample; and receiving from the glucose sensor an amperometric response indicative of a specific glucose concentration in the glucose-containing sample. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Fig. 1 shows a scheme for the preparation of a Pt/PVF/Pt electrode by

immobilization of Pt particles on a PVF matrix;

[0026] Fig. 2 shows the cyclic voltammograms of (a) Bare Pt electrode, (b) electro- depositing platinum on PVF modified Pt electrode in 2mM K₂PtCl₆ + 0.5 M HC1, and (c) Reduction of Pt particles in 0.1M H2SO4. Scan rate: 50mVs^-1;

[0027] Fig. 3 shows the cyclic voltammograms of 5mM glucose in 0.1 M NaOH solution recorded with (a) bare Pt electrode, (b) PVF modified Pt electrode, and (c) Pt/ PVF modified Pt electrode. Scan rate: SOmVs^-1;

[0028] Fig. 4 shows the effect of response current of the Pt/PVF/Pt electrode with change in K₂PtCl₆ concentration;

[0029] Fig. 5 shows the effect of the number of CV scans in K₂PtCl₆ solution on oxidation peak current of 5mM glucose in 0.1 M NaOH;

[0030] Fig. 6 shows the effect of varying applied potential on Pt/PVF/Pt electrode to the oxidation of glucose;

[0031] Fig. 7(a) shows cyclic voltammograms of Pt/PVF/Pt electrode examined at different scan rates: 10, 20, 40, 60, 80, and 100 mV s^-1 with 5.0mM glucose in 0.1 M NaOH; Fig. 7(b) shows the plot of the peak current to the scan rates;

[0032] Fig. 8 shows cyclic voltammograms of Pt/P VF modified Pt electrode in 0.1 M

NaOH with (a) OmM, (b) 5mM, (c) lOmM, (d) 15mM, and (e) 20mM of glucose at scan rate of SOmVs^-1;

[0033] Fig. 9(a) shows the chronoamperometric curves of Pt/PVF/Pt electrode at 0.2 V with successive additions of different concentrations of glucose (0-11 mM) in 0.1 M NaOH at interval of 50s; Fig. 9(b) shows the Calibration curve of peak current (I_p) vs. glucose

concentration; [0034] Fig. 10 shows the interference test of the sensor in 0.1M NaOH at +0.20 V with successive additions of O.lmM AA, 0.2mM UA, O.lmM sucrose and ImM glucose at 50s interval at applied potential of +0.20V;

[0035] Fig. 11 A shows current response of Pt/PVF/Pt electrode on Day 1 and Day 25;

Fig. 1 IB shows current response towards oxidation of 5.0mM glucose of three identical Pt/PVF/Pt electrodes;

[0036] Fig. 12A-12C show chronoamperometric response of the Pt/PVF/Pt sensor obtained for (A) mango, (B) pineapple, and (C) orange juice where Std 1 :lmM, Std 2: 2mM, Std 3: 3mM, Std 4: 4 mM glucose;

[0037] Fig. 13 shows preparation of Au particles deposited on PVF matrix modified Pt electrode;

[0038] Fig. 14 shows CVs of bare Pt electrode(a), PVF/Pt electrode(b), and Au/PVF/Pt electrode (c) towards oxidation of 12mM glucose in 0.1M NaOH. Scan rate: 50mVs^-1;

[0039] Fig. 15A-15B shows (A) Variation of peak current with OmM (a), 4mM(b), 8mM

(c), 12mM(d), 16mM (e) glucose in 0.1M NaOH. (B) Plot of I_p to glucose concentrations. Scan rate: 50m Vs^-1;

[0040] Fig. 16A-16B shows variation of peak current towards oxidation of 1 OmM glucose with different (A) KAuCl₄ concentrations (B) Deposition time;

[0041] Fig. 17A-17B shows (A) Current response of Au/PVF/Pt electrode in 20mM glucose at various scan rates (B) Plot of Ip to scan rate;

[0042] Fig. 18 Variation of applied potential with Au/PVF/Pt electrode towards 16mM glucose in 0.1M NaOH;

[0043] Fig. 19A-19B shows (A) Chronoamperometric response of Au/PVF/Pt modified electrode in 0.1 M NaOH with successive addition of glucose at an interval of 50s (applied potential: + 0.05V). Insert shows the enlarged image of response time at 350s. (B) Calibration plot between current and glucose concentrations; [0044] Fig. 20A-20B shows (A) Effect of interfering species on Au/PVF/Pt electrode in presence of 5mM glucose. (B) The current response of Au/PVF/Pt electrode recorded on Day 1 (a), Day 7 (b), Day 14 (c), and Day 21(d). Insert shows bar graph plotted for response current obtained over 4 weeks;

[0045] Fig. 21 A-21B shows (A) Current response of five identical Au/PVF/Pt electrodes towards 2mM glucose in 0.1M NaOH. Insert shows the current plot for these five identical sensors. (B) Current response recorded for 15 successive measurements with Au/PVF/Pt electrode towards 4mM and 12mM glucose; and

[0046] Fig. 22A-22C shows chronoamperometric response of Au/PVF/Pt electrode in determination of (A) mango juice (B) pineapple juice (C) orange juice. StdlrlmM, Std2: 2mM, Std3: 3mM, Std4: 4mM glucose. Insert shows the respective standard addition graph.

DETAILED DESCRIPTION OF THE INVENTION

I. IN GENERAL

[0047] Before the present materials and methods are described, it is understood that mis invention is not limited to the particular methodology, protocols, materials, and reagents described, as these may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention, which will be limited only by the appended claims.

[0048] It must be noted that as used herein and in the appended claims, the singular forms "a", "an", and "the" include plural reference unless the context clearly dictates otherwise. As well, the terms "a" (or "an"), "one or more" and "at least one" can be used interchangeably herein. It is also to be noted that the terms "comprising", "including", and "having" can be used interchangeably.

[0049] Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are now described. All publications and patents specifically mentioned herein are incorporated by reference for all purposes including describing and disclosing the chemicals, materials, reagents, instruments, statistical analysis and methodologies which are reported in the publications which might be used in connection with the invention. All references cited in this specification are to be taken as indicative of the level of skill in the art. Nothing herein is to be construed as an admission that the invention is not entitled to antedate such disclosure by virtue of prior invention.

[0050] "Glucose sensor" is a sensor used for the detection of glucose level in a sample that has undergone an oxidation reaction.

[0051] "Non-enzymatic glucose sensor" is a glucose sensor that does not rely on enzymes to facilitate or catalyze the oxidation reaction.

[0052] "Polyvinylferrocene" (PVF) is a porous, conducting, redox polymer which has an electroactive ferrocenyl group which establishes simple electrochemistry of a one-electron transfer process.

[0053] "Pt particles" are platinum (Pt) particles used as a catalyst to increase the oxidation of glucose.

[0054] "Au particles" are gold (Au) particles used as a catalyst to increase the oxidation of glucose.

[0055] "Ir particles" are iridium (Ir) particles used as a catalyst to increase the oxidation of glucose.

[0056] "Electrochemical Sensor" is a sensor used for the detection of chemical changes in response to electric charges.

II. THE INVENTION

[0057] Extensive research has been reported for the development of highly sensitive, stable and low cost sensors for detection of glucose. The need for the diagnosis of glucose is not limited to clinical but also widespread to other fields such as food, pharmaceutical and biotechnology. In spite of the availability of numerous glucose sensors in market, the research in this field still needs much of the attention. The electrochemical glucose sensors available are the enzyme based sensors that are fabricated with the use of glucose oxidase (GOx) enzyme. However, these sensors are not stable for long term use as the enzyme loses its activity due to environmental changes. To overcome the shortfalls of enzyme -based sensors, research has been focused towards fabrication of non-enzymatic glucose sensors. In latter, electron transfer for glucose oxidation occurs directly on the electrode surface without the immobilization of enzymes.

[0058] An efficient sensor has high stability, reproducibility, sensitivity, repeatability and low cost along with less response time. This can be achieved by modification of electrode that requires large surface area, easily responsive to analyte and excellent electron transfer capability. To achieve all these factors in a single electrode, it is required to form the composite on the surface of the electrode which can be achieved by forming conducting polymer-metal particles composites. In such types of composite materials, conducting polymer provides high

conductivity and stability while the metal particles are responsible for the electrocatalytic behavior. The redox polymer, polyvinylferrocene (PVF), contains the ferrocenyl group which is electroactive and promotes the one-electron transfer process. The use of PVF for development of sensors is limited till date. The PVF polymer is electrodeposited onto the polymer matrix in its oxidized state (PVF⁺)- The latter state is generated from the electro-oxidation of the reduced form (PVF).

[0059] The inventors have developed glucose sensors which are free of enzymes. The advantages of such non-enzymatic sensors include wide area of application, enhanced

robustness, long shelf life, and minimum efforts in maintenance. To mimic the functions of an enzyme in a conventional glucose sensor, conductive polymers and nanoparticles of precious metals are used. The polymer provides a support for the nanoparticles while the latter are the key component in facilitating the chemical reaction of glucose.

[0060] Numerous studies have been based on electro-oxidation of glucose with a variety of electrode materials such as Au, Pt, and Ir. This includes various methods of preparation and use of different catalysts.

[0061] Studies have shown that the employment of different polymer films on electrodes as the polymer matrix is stabilized and provides more active sites for the immobilization of a catalyst. Moreover, these polymers have good mechanical and conducting properties. [0062] Numerous conducting polymeric films have been investigated for glucose oxidation on an electrode. These include polyaniline (PANI), poly (3,4-ethylenedioxythiophene) (PEDOT), polypyrrole (PPY), polythiophenes, poly(ophenylenediamine) (PoPD) and

polyvinylferrocenium. The incorporation of noble metals such as Cu, Ni, Pt, Pd, Au and Ir into the conducting polymer matrix also act as a catalyst and has shown to increase the oxidation of glucose.

[0063] Although the present invention is being described with respect to PVF and Pt, Au, or Ir, it is understood that any polymeric films, for example, polyaniline (PANI), poly (3,4- ethylenedioxythiophene) (PEDOT), polypyrrole (PPY), polythiophenes,

poly(ophenylenediarnine) (PoPD) and polyvinylferrocenium; and any noble metals: Cu, Ni, Pt, Pd, Au, If and bi-metallic metals (e.g., Pt-Au), may be used.

[0064] Polyvinyl ferrocene (PVF) being a conducting as well as redox polymer has several advantages to being used in preparation of glucose sensors. This polymer has an electroactive ferrocenyl group which establishes simple electrochemistry of one-electron transfer process. Several studies are based on the different preparation methods and electrochemical activity of this redox polymer matrix on a Pt electrode. The oxidized form of the polymer (PVF⁺) can be electro-deposited onto the electrode surface by the electro-oxidation of the reduced form (PVF). After PVF⁺ is deposited onto the electrode surface, it can be switched to PVF by applying an external potential to the electrode. The reduced form of PVF can then undergo a redox reaction to form catalyst metal particles (C) into its matrix.

[0065] nPVF + Cⁿ⁺→nPVF⁺ + C

[0066] The incorporation of Pt, Au, or Ir particles has been reported to improve the properties of the sensor as it increases the effective surface area of the electrode. Platinum, Gold and Iridium particles as a catalyst are a point of interest due to their high electrocatalytic activities and also improved physical and chemical properties.

[0067] The development of a non-enzymatic glucose sensor based on a Pt electrode modified with Pt, Au, or Ir particles immobilized into the PVF matrix is provided herein. The influence of various factors such as analyte concentration, amperometric response, selectivity, sensitivity and stability in the response of the modified electrode has been studied. Pt, Au, or Ir particles were immobilized into the polymer matrix through an electro-deposition method. The influence of the amount of Pt, Au, or Ir particles deposited, number of cycles for electro- deposition, and the concentration of K₂PtCl₆ (for Pt) or KAuCl₄ (for Au) has also been established.

[0068] In one embodiment, described in the Example 1 below, the prepared Pt/PVF/Pt electrode showed high stability, sensitivity, stability and reproducibility towards oxidation of glucose.

[0069] Gold nanoparticles have gained attention as they have superior biocompatibility, better electrocatalytic behavior, easy immobilization on polymer film, fast response, anti- poisoning feature, and wide range of oxidation potential both in neutral and alkaline electrolytes. The use of Au particles has been researched in the development of non-enzymatic glucose sensor and this involves the process of electrodeposition of the Au particles on the surface of electrode. Considering the properties of Au particles and PVF, the inventors have prepared Au-PVF composite in this study in which the inventors have used the method of direct deposition of Au particles on PVF matrix without applying potential. It has been demonstrated the use of PVF-Au composite in the presence of enzyme GOx for the detection of glucose. The inventors' study shows that with optimization of the conditions for the deposition of Au nanoparticles, the inventors can increase the performance of our sensor based on Au nanoparticles, without the use of enzymes.

[0070] The inventors modified the Pt electrode with direct deposition of the Au particles on PVF matrix. This is the first report where the Au-PVF composite has been modified onto a Pt electrode to be used for non-enzymatic glucose sensor. The concentration of the KAuCl₄ solution and deposition time for the Au particles was optimized for better performance of the sensor. The characterization of the sensor has been studied with the use of cyclic voltammetry (CV) technique. The proposed sensor (Au/PVF/Pt) has been evaluated for its current response towards different concentrations of glucose. The performance parameters such as sensitivity, selectivity, stability, repeatability, reproducibility, detection limits and response time has also been evaluated using chronoamperometry (CA) technique. Further, the applicability of the Au/PVF/Pt sensor was confirmed from successful detection of glucose in various juice samples. [0071] In one embodiment, described in the Example 2 below, the prepared Au/PVF/Pt electrode showed high stability, sensitivity, stability and reproducibility towards oxidation of glucose.

[0072] Alter testing a few precious metals commonly believed to be efficacious catalysts, the inventors found that nanoparticles of iridium (Ir) possess a promising potential to be an excellent catalyst The conclusion is based on a head-to-head comparison with cobalt

nanoparticles. Iridium is proved to be an effective catalyst for glucose sensing based on the lab tests.

[0073] In other embodiments, Iridium proved to be a good substitute for Platinum and

Gold particles.

III. EXAMPLES

[0074] Example 1

[0075] Fabrication of Non-Enzvmatic Sensor based on Pt/PVF on modified Pt electrode for Determination of Glucose

[0076] Material and reagents

[0077] The chemicals used include Potassium hexachloroplarinate (TV) (K₂PtCl₆) solution, Polyvinyl ferrocene (PVF), Hydrochloric acid (HC1, 36.0-38.0%), Dichloromethane (CH₂Cl₂), Tetrabutylammonium perchlorate (TBAP), Sodium hydroxide (NaOH), uric acid (UA), ascorbic acid (AA), D-Glucose, and sucrose. All the chemicals used were of analytical grade.

[0078] Glucose solutions were prepared in 0.1 M NaOH. All aqueous solutions were prepared in deionized water.

[0079] Apparatus

[0080] All electrochemical experiments were performed using an electrochemical analyzer (CHI750C Electrochemical Workstation). A three electrode systems composed of a platinum wire as the counter electrode, calomel saturated electrode as the reference electrode, and the modified Pt as the working electrode were employed for the electrochemical measurements. All experiments were carried out at room temperature.

[0081] Preparation of PVF coated Pt electrode

[0082] The working Pt electrode was polished with 0.05 μm alumina slurry, rinsed with water, then ultrasonicated for a few minutes and dried in air.

[0083] The PVF was coated on a Pt electrode by electro-oxidation in dichloromethane

(CH2CI2) solution. The CH2CI2 solution contained 0.1M TBAP and 2.3M PVF.

[0084] The oxidized state of PVF (PVF⁺) does not dissolve in CH₂Cl₂ solution while the reduced state (PVF) dissolves in CH.C1₂ solution. The PVF is oxidized to PVF⁺by applying a high potential of +0.7V for three minutes and then reducing potential to 0V for another three minutes.

[0085] As a result, the produced PVF⁺ClO₄- was electro-precipitated on Pt electrode. The film formed was dried and washed with 0.1M NaOH for electro-deposition of Pt particles.

[0086] Preparation of Pt on PVF

[0087] Platinum was electro-deposited on the PVF polymer film from 2mM K₂PtCl₆ in

0.5M HC1 solution.

[0088] A potential was applied to the PVF⁺ polymer film between -0.20V and +0.35Vat

50mVs"' scan rate for 30 cycles, which changes PVF⁺ to PVF. K₂PtCl₆ then chemically reacts with PVF to form Pt particles in the polymer film. These steps may happen sequentially or synergistically.

[0089] After the electro-deposition process, the electrode was dried for a day and rinsed with deionized water.

[0090] Electrochemical redaction of Pt particles

[0091] The particles abiding to ferrocenium are Pt(0) neutral nanoparticles. The electrochemical reduction is to facilitate the formation of Pt(0) particles. [Pt(IV) ->Pt(0)]. [0092] Alternatively, the particles abiding to ferrocenium are Pt(II) nanoparticles. The electrochemical reduction is to facilitate the formation of Pt(H) particles. [Pt(IV)→Pt(II)].

[0093] The resulting modified electrode showed catalytic behavior towards oxidation of glucose in 0.1M NaOH. The entire scheme for preparation of modified Pt/PVF/Pt electrode is illustrated in Fig. 1.

[0094] Results and Discussion

[0095] Electrochemical characterization of the modified electrode

[0096] Cyclic Voltammetry (CV) technique has been used for characterization of the preparation process of the modified electrode.

[0097] The CVs of (a) bare Pt electrode, (b) Pt/PVF* on Pt electrode, and (c)

electrochemical reduction of Pt on PVF / Pt electrode are represented in Fig. 2.

[0098] hi voltammogram (b), the oxidation peak of PVF can be observed at potential

+0.40V and the corresponding reduction peak of PVF appears at potential of +0.28V (vs SCE). The oxidation of Pt particles is observed in the region +0.02 V to +0.1 V.

[0099] As polyferrocenuim ion (PVF⁺) is positively charged it offers easy immobilization to the negatively charged Pt particles. Moreover, PVF being a redox and porous polymer provides an easy site for Pt particles resulting in the increased electrocatalytic activity.

[00100] The oxidation of glucose was studied with bare Pt electrode, PVF coated Pt electrode, and Pt/PVF/Pt electrode in 0.1 M NaOH. It is well indicated from Fig. 3 that the Pt/PVF/Pt electrode has higher electrochemical activity compared to the Pt substrate electrode towards oxidation of glucose in 0.1M NaOH indicating that Pt/PVF/Pt electrode can be promising in achieving good electrocatalytic activity.

[00101] Effect of K₂PtCl₆ concentration

[00102] For electro-deposition of platinum particles on PVF coated Pt electrode, it is ideal to choose optimum concentration of K₂PtCl₆ where the response current is highest. The concentration of K₂PtCl₆ solution was varied between 0.5 mM and 5.0 mM. As shown in Fig 4, the Pt/FVF/Pt electrode response increased with concentration up to 2.0 mM where maximum response current was observed, after which current started decreasing.

[00103] It is evident that the increasing concentrations K₂PtCl₆ leads to alteration in Pt particles size which results in decreased catalytic activity. Hence, K₂PtCl₆ concentration was chosen as 2.0 mM for electro-deposition of Pt particles on PVF coated Pt electrode.

[00104] Effect of number of cycles

[00105] The number of cycles is an important factor to be considered while electro- depositing Pt particles into PVF matrix through Cyclic Voltammetry. The number of cycles influences the amount of Pt particles that can be incorporated into the polymer matrix.

[00106] The CV scan was conducted in 2mM K₂PtCl₆ solution for 5, 10, 15, 20, 30, 35 and 40 cycles and recorded potential for oxidation of 5mM glucose in 0.1M NaOH (shown in Fig. 5). As observed, the peak current increases initially and reached maximum for 30 cycles and decreased afterwards. Hence, CV scan was run for 30 cycles during deposition of Pt particles on PVF matrix.

[0010η Effect of applied potential

[00108] The effect of applied potential on Pt/PVF/Pt electrode to glucose was examined at different potentials between -0.2 V to +0.8 V, keeping the other experimental conditions constant. The response current increased regularly on modified Pt electrode with increase of the applied potential from -0.2V to +0.2V. When the applied potential was higher than +0.2 V, the current gradually fell (Fig. 6). Thus, a potential of +0.2 V was preferred as operational potential in chronoamperometric experiments.

[00109] Effect of Scan rate

[00110] The effect of scan rates on the oxidation of glucose at the Pt/PVF modified Pt electrode was investigated. Cyclic Voltammograms were recorded at different scan rates (between 10-100m Vs^-1) in 5mM glucose solution. As shown in Fig. 7(a), peak current due to oxidation of glucose increases with increase in scan rate. The plot between I_p vs. scan rate (Fig. 7(b)) was linear (R²= 0.992) which indicates that electrochemical kinetics is surface controlled phenomenon which is ideal for oxidation of glucose. [00111] Electrocatalvtic behavior of glucose

[00112] Electrocatalytic properties of Pt/PVF/Pt electrode were examined towards oxidation of glucose using cyclic voltammetry in different concentrations of glucose. Typical CVs obtained are shown in Fig. 8. The performance of electrode towards oxidation of glucose was conducted in 0.1 M NaOH with and without glucose (5mM-20mM) from -0.8V to +0.8V with scan rate of 50mVs^-1 using CV.

[00113] In alkaline solution, no obvious peak for the oxidation of glucose is observed in solution without glucose. The oxidation current is observed between -0.40 and -0.18 V for different concentrations of glucose. As the concentration of glucose is increased from 5mM to 20mM, the anodic peak is shifted towards the high potential region indicating glucose can be electrochemically reduced on the Pt/PVF/Pt electrode over a broad range of glucose

concentrations.

[00114] For the detection of 20mM glucose, the peak current of -3.168x 10^-5A is observed.

[00115] Amperometric response of Pt/PVF/Pt sensor towards glucose

[00116] The amperometric response of glucose was investigated with Pt/PVF/Pt electrode at an optimum potential of +0.2V. As shown in Fig. 9(a), the modified electrode displayed fast, stable, and well-defined amperometric response with successive additions of glucose in continuously stirred 0.1 M NaOH solution. It is evident that the response current of the modified electrode increases rapidly with each concentration of glucose being added. Also, the modified electrode responded quickly with each addition of glucose. In addition, the time taken to achieve 95% of the steady-state current is not more than 3s.

[00117] The calibration plot between electrocatalytic current and different concentrations of glucose at Pt/PVF/Pt electrode is shown in Fig. 9(b). The sensor exhibited sensitivity of 327 μΑmM^-1 cm^-2 with a correlation coefficient of 0.997. The upper limit of linear range is 11mM and detection limit of 2.6x10^-3mM at a signal-to-noise ratio of 3.

[00118] From the results, it can be confirmed that the sensor of the present application exhibits optimum detection limit, high sensitivity, fast response, and wide linear range. The appreciable linear range may be due to larger surface area and more active sites for oxidation of glucose. The fast response and sensitivity of the sensor might be due to the catalytic action of Pt particles which promotes the electron transfer during the oxidation of glucose.

[00119] Anti-Interference analysis and Stability

[00120] One of the key challenges with non-enzymatic glucose sensors is the ability to distinguish the response current of glucose from that of interfering substances, such as ascorbic acid, uric acid, and sucrose. These interfering ions have activities similar to the glucose and hence might affect oxidation of glucose. The normal physiological level of glucose is much higher than interfering substances (~ 30 times) in human blood as well as in food samples. Selectivity of Pt/PVF/Pt electrode by successive additions of O.lmM AA, 0.2mM UA, O.lmM sucrose and ImM glucose in 0.1 M NaOH was conducted.

[00121] Fig. 10 represents the selectivity results obtained by step-wise addition of AA, UA, sucrose, and glucose at applied potential of +0.20V. The results show that the current response of glucose was much higher than that of interferents. This indicates that the sensor based on Pt/PVF/Pt electrode has acceptable anti-interference ability.

[00122] Stability and Reproducibility

[00123] The stability of the Pt/PVF/Pt modified electrode was assessed by measuring the current response to 5.0mM glucose after a period of 25days (Fig. 11 A). The sensor retains 78.2% of its initial current response after 25days. Hence, it is evident that the proposed sensor shows good stability.

[00124] The reproducibility of Pt/PVF/Pt electrode was evaluated for three Pt/PVF modified Pt electrodes and their current response to 5mM glucose was studied (Fig. 1 IB). The relative standard deviation (RSD) of 7.3% was observed, confirming the appreciable

reproducibility of the proposed method. Hence, the method is relevant for practical use.

[00125] Application of the Pt/PVF/Pt electrode: Glucose Detection in Juices

[00126] The analytical utilization of the proposed sensor was studied for detection of glucose in juice samples using standard addition method. Three different varieties of juices (mango, orange, and pineapple) were obtained from the local store and the concentration of glucose was determined by the present method and the results were compared to the values obtained from a commercial glucose meter (Truetrack®).

[00127] Briefly, each of these samples was diluted to 100 folds for standard addition method. Equal volumes of the diluted juice samples were spiked with different concentrations of glucose viz, ImM, 2mM, 3mM, and 4mM, and the as-prepared solutions were marked as Stdl , Std 2, Std 3, and Std4 respectively.

[00128] Figs. 12A, B and C show the chronamperometric response when equal volumes of samples, Std 1 , Std 2, Std 3, and Std 4, were added at an interval of 50s. In all three juice samples, linear regression coefficient (R²) was observed.

[00129] Table 1 (below) compares the glucose concentration values in each of the juice samples obtained from the present method to that of a commercial glucose meter. As observed, the values indicated by the sensor are in close agreement to the values shown by the commercial sensor with minimum bias values. These results signify the applicability of the proposed sensor in detection of glucose for practical use.

Table 1: Determination of glucose in different juice samples [00130] Conclusion

[00131] In summary, the non-enzymatic glucose sensor based on redox polymer PVF was fabricated. The results show that PVF provides an efficient matrix for the immobilization of Pt particles. The proposed method of preparation was novel, efficient, reproducible, and simple. The Pt/PVF/Pt electrode exhibited high sensitivity of

and low detection limit of 2.6x10^-3(S/N=3). Moreover, the sensor exhibited strong response to glucose in presence of other interferents such as ascorbic acid, uric acid and sucrose. Finally, the applicability of the proposed sensor was confirmed from the successful determination of glucose concentration in different juice samples. The results indicate that Pt/PVF/Pt sensor can be employed for detection of glucose for practical purpose.

[00132] Example 2

[00133] Non-Enzymatic Glucose Sensor of High Sensitivity Fabricated with Direct Deposition of Au Particles on Polyvinylferrocene Film Modified Pt Electrode

[00134] Chemicals & Apparatus

[00135] Potassium chloride (KC1, Fisher Scientific, 100.2%), potassium tetrachloroaurate (III) (KAuCU, Aldrich, 98%), polyvinylferrocene (PVF, Polysciences), dichloromethane (CH₂Cl₂, Acros Organics, 99.9%), tetrabutylammonium perchlorate (TBAP, Fluka Analytical, ≥99.0%), sodium hydroxide (NaOH, Fisher Scientific, 99.4%), uric acid (UA, Nutritional Biochemicals Corporation), ascorbic Acid (AA, Acros Organics), sucrose (Aldrich), and D- glucose (Macron Fine Chemicals). The KAuCl₄ solution was prepared in 0.01M KC1. All the water-based solutions were prepared in deionized water and glucose solution was prepared in 0.1 M NaOH. All the experiments were performed with 3-electrode system set up with modified Pt electrode (working electrode), Pt wire electrode (counter electrode), and calomel electrode (SCE) (reference electrode). These electrodes were purchased from CH Instruments, Inc., USA. The CV and CA techniques were performed using electrochemical analyzer (CHI750C

Electrochemical Workstation). When not in use, the working modified Pt electrode was stored at room temperature. All the experiments were performed at room temperature.

[00136] Preparation of Au/PVF/Pt glucose sensor

[0013η The bare Pt electrode (working electrode) was first polished using alumina slurries (in order: 0.1, 0.3 and 0.05 μm ) till clean surface, rinsed and thereafter ultrasonicated in deionized water for few minutes. The polished electrode was then potential sweep between - 0.2V and +0.7V in 1M H2S0₄tiU a stable voltammogram of Pt electrode is obtained. The electrode was rinsed and dried in air. The PVF matrix was electrodeposited on the polished Pt electrode from CH2CI2 solution containing 2.5mM TBAP and 1.5mM PVF. PVF⁺ does not dissolve in CH2CI2 solution while the reduced state, PVF, readily dissolve. The oxidation of PVF to PVF⁺ is carried by applying potential of +0.7 V for 180s for 2-3 times followed by potential reduction to 0V for another 180s to obtain PVF⁺ C10₄-on the Pt electrode. Subsequently, Au particles were directly deposited on PVF⁺ coated Pt electrode by placing the electrode in KAuCU solution without applying potential or even stirring. Briefly, it is a redox reaction in which PVF is oxidized to PVF^+- and Au⁺³(ui KAuCU) is chemically reduced to Au particles that gets deposit on PVF^1- coated Pt electrode. The chemical reaction that takes place is represented in Eq. 1

[00138] 3 PVF + AuCl₄-→ 3PVF⁺ + Au + Cl- (1)

[00139] The as prepared electrode was dried in air and then rinsed with 0 1 M NaOH This electrode was labeled as Au/PVF/Pt electrode. T

concentrations of glucose (sweeping potential: -0

procedure followed to prepare Au/PVF/Pt electrode is represented in Fig. 13.

[00140] Results & Discussions

[00141] Characterization of working electrode

[00142] The odified Au/PVF/Pt working electrode was fabricated in two steps. First, the

PVF matrix was deposited on the Pt electrode from a CH2CI2 solution using CV and in the second step Au particles were directly deposited on PVF film from KAuCl₄ solution. Fig. 14 shows the cyclic voltammograms obtained in 12mM glucose solution for the bare Pt, PVF modified Pt and Au particles deposited PVF on Pt electrode. No obvious peaks towards oxidation of glucose is observed for bare Pt and PVF modified Pt electrode (voltammograms (a) and (c)) while for Au particles on PVF modified Pt electrode (voltammogram (c)), the onset of glucose oxidation is observed in the region from +0.22V to +0.12V with peak current of 7.63μΑ. This can be attributed to the fact that Au particles attached to the PVF matrix contribute to the catalytic action which enhances the oxidation of glucose to gluconolactone.

[00143] The electro-oxidation process of glucose involves the adsorption of

dehydrogenated species that is initiated with the formation of Au hydroxides (AuOH). In alkaline medium, OH" ions are readily absorbed by gold surface leading to formation of Au hydroxides. Hence the inventors prefer to study performance of the sensor in alkaline electrolyte (0.1M NaOH).

[00144] The as-prepared Au/PVF/Pt modified electrode was use to study the variation of the peak current (I_p) with the different concentrations of glucose solutions in 0.1 M NaOH. As indicated from Fig. 15 A, anodic peak current increases with the increase in concentration of glucose (0-16mM). As the concentration of glucose is increased, the anodic peak is shifted towards the high potential region indicating glucose can be electrochemically reduced on the Au/PVF/Pt electrode over a broad range of glucose concentrations. A linear graph is obtained for the variation of current with increasing glucose concentration with regression coefficient of 0.991. Fig. 15B shows that the response of Au/PVF/Pt electrode varies linearly with

concentration of glucose.

[00145] Optimization

[00146] As the oxidation of glucose is greatly enhanced due to the electrocatalytic behavior of Au particles, the optimum concentration of the Au particles deposited on the PVF film is an essential criterion to be selected for the better performance of the sensor. To achieve this, the inventors prepared different concentrations of KAuCl₄ solutions (0.25mM-3mM) in 0.01 M KC1 and recorded the response current towards oxidation of glucose. Fig. 16A displays the variation of peak current with different KAuCl₄ concentrations. As observed, the peak current increases up to 0.5mM KAuCl₄ after which the catalytic action of Au decreases and peak current gradually decrease. This can be attributed to the fact that concentration > 0.5mM results in aggregation of Au particles that causes decrease in electrocatalytic performance of the electrode towards oxidation of glucose. Thus, the inventors selected 0.5mM KAuCl₄ concentration for deposition of Au particles.

[00147] Furthermore, deposition time required for Au particles was also considered during the fabrication process of the sensor. The Au particles were allowed to deposit on the PVF/Pt electrode for different time period (60s -240s) and the current was observed towards oxidation of glucose. As evident from Fig. 16B that the maximum peak current is observed at 180s and afterwards it decreases. Hence, the optimum growth time for Au particles was selected as 180s.

[00148] Effect of Scan Rate

[00149] The Au/PVF/Pt sensor was further investigated towards glucose oxidation with the variation in scan rates using CV technique. Fig. 17A shows the voltammograms obtained towards 20mM glucose in 0.1M NaOH at scan rates of 10, 20, 40, 60, 80 and lOOmVs^-1. From the voltammograms obtained, it is evident that with the increase in scan rate glucose oxidation peak current (I_p) also increases. Furthermore, the plot I_p to scan rate (v) is linear with regression coefficient 0.991 (Fig. 17B) indicating that the glucose oxidation process on the Au/PVF/Pt electrode is controlled by adsorption of glucose on surface of the electrode.

[00150] Analytic Parameters

[00151] Chronoamperometric response of Au/PVF/Pt modified electrode

[00152] For conducting the chronoamperometric experiment of the Au/PVF/Pt modified electrode it is essential to select a potential where the substantial current due to oxidation of glucose is observed. Fig. 18 shows the hydrodynamic modulation voltammogram performed for 16mM glucose in 0.1M NaOH. As indicated from figure, current towards the oxidation of glucose gradually increases to +0.05 V after which a gradual decrease is observed. Thus, the inventors choose +0.05 V as applied potential for the subsequent experiments.

[00153] The chronoamperometric response towards oxidation of glucose was done at an applied potential of +0.05 V with successive addition of glucose in 0.1 M NaOH at an interval of 50s. The solution was stirred constantly during the run of the experiment. Fig. 19A shows the current response obtained for Au/PVF/Pt electrode that increases with the increase in glucose concentrations. The sensor achieved 95% of the steady-state current value within a short span of 2s (insert of Fig. 19A). The calibration curve observed for the Au/PVF/Pt sensor in the wide concentration range from 10μΜ to 6mM is shown in Fig. 19B. Two linear ranges were observed, ίτοηι10μΜ-80μΜ and the other one from ΙΟΟμΜ -6mM with regression coefficient 0.9902 and 0.9906 respectively. The wide linear range might be attributed to the large surface area of the electrode available for adsorption and reaction of glucose molecules.

[00154] The sensitivities for each of these ranges were calculated using the Eq. 2.

[00155]

[00156] The active surface area of the working Au/PVF modified Pt electrode is calculated with the help of Randles-Sevcik Equation (Eq. 3),

[00157] I_p= 268600 n^(3/2)Α D^(1/2) C υ ^(1/2) (3) [00158] where, n - number of electron transfer, I_p - peak current electrode, D - diffusion coefficient, C - bulk concentration, A - area of the electrode, and υ - scan rate. From Eq. (3), the active surface area calculated for the Au/PVF/Pt electrode is 0.00027cm². This value is very less that seems to be contradictory to the actual geometrical surface area of the electrode. However, it should be analyzed here that that concentration of Au and PVF used in mis experiment is very low that have resulted in less active surface area available for oxidation. However, even with such small area the inventors were able to achieve high sensitivity for the sensor.

[00159] Substituting the value of active surface area in Eq. (2), the sensitivity obtained for 10μΜ-80μΜ is 3236.3uA mM^-1 cm^-2 and for the linear range ΙΟΟμΜ -6mM is 730.3 μΑ mM^-1cm^-2. The high sensitivity obtained at lower concentrations might be due to the rapid electron transfer and increased electrocatalytic behavior due to the presence of Au particles. While the electron transfer might be interfered by the intermediates formed at high glucose concentrations accounting for less sensitivity than low concentrations.

100160] The limit of detection of the sensor is 0.068mM (S/N=3), calculated using the Eq.

(4)

[00161]

(4)

[00162] Where, σ - standard deviation of blank solution (10 readings) and s - slope of the calibration curve. Table 1 compares the performance parameters of the sensor to other sensors recently reported using Au particles. From the results, it is evident that the proposed sensor has superior or comparable analytical performance. Moreover, this is the first paper where PVF, redox polymer, along with Au particles composite has been employed for fabrication of highly sensitive non-enzymatic glucose sensor.

[00163] Table 1: Comparison of analytical parameters of the Au/PVF/Pt sensor to recently reported non-enzymatic glucose sensors based on Au particles.

y

[00164] NPs: nanoparticles; MWCNTs: Multiwalled carbon nanotubes; FLG: few layered graphene; GONRs: Graphene oxide nanoribbons; DGNs: Dendrite-like gold nanostructures; LDH: Ni-Al layered double hydroxide; CNTs: Single-walled carbon nanotubes; NPGF:

Nanoporous gold film; Hp-AuNs: Hyperbranched pine-like gold nanostructure; NA-Not Applicable; "Unity of sensitivity is mA mM^-1 cm^-2

[00165] Selectivity & Stability

[00166] In the development of non-enzymatic glucose sensor it is required to fabricate a sensor that can show selectivity to glucose only in the presence of many interference species. The glucose level found in food and human blood is higher than interfering species such as UA, AA and sucrose. In the inventors' present work, the proposed Au/PVF/Pt sensor was studied for its selectivity to glucose in presence of AA, UA, and sucrose. The CA experiment was performed by successively adding 0.1 mM AA, 0.1 mM UA, O.lmM sucrose, and 5mM glucose in 0.1M NaOH at an interval of 50s. As shown in Fig. 20A, the current response for glucose is much higher than other interferents. This confirms that the proposed Au/PVF/Pt sensor shows excellent selectivity to glucose.

[00167] The stability of a sensor is defined by its performance over a period of time. To study the stability of the Au/PVF/Pt sensor, its current response towards oxidation of lmM glucose was recorded once in 7 days for a period of 4 weeks. It was observed that the response current decreases to only 9.3% of its initial value (Fig.20B). This confirms that the sensor exhibits excellent stability. When not in use, the sensor was stored at room temperature.

[00168] iucibilitv & Repeatability

[00169] Reproducibility refers to the agreement between current responses obtained for same analyte from identical electrodes prepared with same fabrication process. The

reproducibility of the Au/PVF/Pt sensor was assessed by fabricating five identical sensors with same procedure. It was observed that RSD of only 2.96% is observed when used against 2mM glucose in 0.1M NaOH (Fig. 21 A). Repeatability depicts the agreement between the successive current responses obtained for the same analyte. The repeatability of the proposed sensor was studied by recording fifteen current response measurements with 4mM glucose as well as with 12mM glucose (Fig. 2 IB). It was observed that with both these concentrations of glucose RSD of only 3.03% is observed. From these data, the inventors can predict that the Au/PVF/Pt sensor shows excellent reproducibility and repeatability.

[00170] Applicability of Au/PVF/Pt sensor for detection of glucose in Juice

[00171] The analytical application of the as-prepared Au/PVF/Pt sensor was studied with the detection of glucose in different boxed juice samples. Three different varieties of boxed juices (mango, pineapple, and orange) were taken from local store and each of them was diluted to 1 : 100 dilution factors for standard addition method. The results obtained were compared to the commercial glucose meter (TRUEMetrix®). Equal volumes of the diluted juice samples were spiked with different concentrations of glucose viz, lmM, 2mM, 3mM, and 4mM and the as- prepared solutions were marked as Std 1, Std 2, Std 3, and Std 4 respectively. Figs. 22 A, B and C shows the chronoamperometric response of Au/PVF/Pt electrode when equal volumes of sample, Std 1, Std 2 , Std 3, Std 4 were added sequentially at an interval of 50s. Insert in each of these figures show the respective standard addition plot between the response current and glucose concentration. As observed for each of the samples linear regression coefficient (R²= 0.99) is obtained. The concentration of the glucose obtained from the inventors' method was compared with the values from commercial glucose meter. Table 2 indicates that the

concentrations of the glucose obtained with proposed Au/PVF/Pt sensor are in good agreement with reference glucose meter (with minimum bias). These results confirm that the sensor is reliable for accurate measurements of the glucose for practical purpose.

[00172] Table 2: Concentration of glucose recorded in various boxed juice samples

[00173] Conclusion

[00174] A highly sensitive non-enzymatic glucose sensor was fabricated with the direct deposition of Au particles on PVF matrix modified Pt electrode for determination of glucose in juices. This is the first paper where a redox polymer, PVF, and Au composite has been employed for the development of non-enzymatic glucose sensor. The fabrication process is simple and reproducible. The presence of Au particles provided active surface area for an increased electrocatalytic activity. The sensor exhibited two wide linear ranges, 10μΜ-80μΜ and ΙΟΟμΜ - 6mM, with ultrahigh sensitivity of 3236.3 and 730.3 uA mM^-1 cm ^~2 respectively. The response time of the sensor was very less of ~2s only. Apart from these performance parameters, the proposed Au/PVF/Pt sensor has shown excellent stability and repeatability. Also, the sensor was able to show selectivity to only glucose in presence of many other interfering species. As the sensor does not use enzymes it would cost less compare to the enzyme-based glucose sensor available for practical use. The applicability of the as-prepared sensor was successfully determined with detection of glucose in a variety of boxed juice samples and these results were comparable to commercial glucose meter. The excellent electrocatalytic behavior makes this sensor promising non-enzymatic glucose sensor for practical use.

[00175] Example 3

[00176] Iridium Nanoparticleg as the Catalyst in Non-Enzymatic Glucose Sensors

[00177] After testing a few precious metals commonly believed to be efficacious catalysts, the inventors found that nanoparticles of iridium (Ir) possess a promising potential to be an excellent catalyst. The conclusion is based on a head-to-head comparison with cobalt

nanoparticles. Iridium is proved to be an effective catalyst for glucose sensing based on the lab tests.

[00178] As can be appreciated, the results described in the above examples support the utility of the method described and claimed herein for fabricating a non-enzymatic glucose sensor. Other embodiments and uses of the invention will be apparent to those skilled in the art from consideration from the specification and practice of the invention disclosed herein. All references cited herein for any reason, including all journal citations and U.S./foreign patents and patent applications, if present, are specifically and entirely incorporated herein by reference. It is understood that the invention is not confined to the specific compositions, materials, methods, formulations, manufacturing conditions, etc., herein illustrated and described, but embraces such modified forms thereof as come within the scope of the following claims.

Claims

CLAIMS What is claimed is:

1. A method of fabricating a non-enzymatic glucose sensor, comprising:

(a) electrodepositing a redox polymer film on a substrate electrode;

(b) electrodepositing noble metal particles to abide on the redox polymer film; and

(c) electrochemically reducing the noble metal particles on the redox polymer film;

wherein a non-enzymatic glucose sensor is provided that yields an amperometric response to a glucose concentration contacted with the non-enzymatic glucose sensor.

2. The method of claim 1 , wherein the redox polymer film is an oxidized polyvinyl

ferrocene (PVF⁺), the substrate electrode is a platinum (Pt) substrate electrode, and the noble metal is at least one of a platinum (Pt), gold (Au), and iridium (Ir).

3. The method of claim 2, wherein electrodepositing the Pt substrate electrode with the PVF⁺ takes place in a dichloromethane (CH₂CI₂) solution.

4. The method of claim 3 , further comprising the step of:

electro-oxidizing PVF to PVF⁺ wherein the electro-oxidizing step is approximately 180 seconds in duration.

5. The method of claim 4, further comprising the steps of:

forming polyvinylferrocenium ion perchlorate (PVF⁺ClO₄-); and

electro-precipitating the PVF^ClO-f on the Pt substrate electrode.

6. The method of claim 2, wherein Pt is electrodeposited on the PVF* polymer film by submerging the P VF⁺ polymer film with K₂PtCl₆ in HC1 solution.

7. The method of claim 6, wherein the concentration of the K₂PtCl₆ is 2.0 mM.

8. The method of any one of claim 6 and 7, wherein the Pt is electrodeposited on the PVF⁺ polymer film by cyclic voltammetry (C V) scan.

9. The method of claim 8, wherein the CV scan is at about 50mVs^-1 scan rate for 30 cycles.

10. The method of claim 9, wherein the Pt is electrodeposited on the PVF polymer film by an applied potential of about 0.2 Y.

11. The method of claim 2, wherein the electrochemical reduction of Pt particles is from a PttTV) oxidation state to a Pt(II) or Pt(0) oxidation state.

12. The method of claim 11, wherein electrochemical reduction occurs in H2SO4 solution.

13. The method of claim 2, wherein the Au is electrodeposited on the PVF⁺ polymer film by submerging the PVF⁺ polymer film with KAuCl₄ in HC1 solution.

14. A non-enzymatic glucose sensor for detecting a concentration level of glucose,

comprising:

a platinum (Pt) substrate electrode;

a Polyvinyl ferrocene (PVF⁺) polymer matrix coating the Pt substrate electrode; and

a plurality of Pt particles electrochemically deposited on the PVF*- matrix;

wherein the non-enzymatic glucose sensor is fabricated according to any one of claims 1-13.

15. A non-enzymatic glucose sensor for detecting a concentration level of glucose,

comprising:

a platinum (Pt) substrate electrode;

a Polyvinyl ferrocene (PVF⁺) polymer matrix coating the Pt substrate electrode; and a plurality of Iridium (Ir) particles electrochemically deposited on the PVF⁺ matrix;

wherein the non-enzymatic glucose sensor is fabricated according to any one of claims 1-13.

16. A non-enzymatic glucose sensor for detecting a concentration level of glucose,

comprising:

a platinum (Pt) substrate electrode;

a Polyvinyl ferrocene (PVF⁺) polymer matrix coating the Pt substrate electrode; and

a plurality of gold (Au) particles electrochemically deposited on the PVF* matrix; wherein the non-enzymatic glucose sensor is fabricated according to any one of claims 1-13.

17. A method of detecting a glucose concentration level in a sample, comprising:

contacting a glucose sensor fabricated according to any one of claims 1-13 with a glucose-containing sample; and

receiving from the glucose sensor an amperometric response indicative of a specific glucose concentration in the glucose-containing sample.