CN103245653A

CN103245653A - Uniform-height nano-silver surface-enhanced Raman scattering active substrate

Info

Publication number: CN103245653A
Application number: CN2013101621673A
Authority: CN
Inventors: 郭隆华; 徐杨; 杨黄浩; 邱彬; 林振宇; 陈国南
Original assignee: Fuzhou University
Current assignee: Fuzhou University
Priority date: 2013-05-06
Filing date: 2013-05-06
Publication date: 2013-08-14

Abstract

The invention discloses a uniform-height nano-silver SERS (Surface Enhanced Raman scattering) active substrate and a preparation method thereof. A surfactant CTAB (Cetyltrimethyl Ammonium Bromide) serves as a coupling agent; glass, silicon or silicon dioxide serves as a solid-phase matrix; nano-silver particles are fixed by using a physical absorption method and are distributed on the surface of a solid-phase substrate in a single-layer manner; CTAB generates autogenous shrinkage in the drying process to reduce the distance between the two adjacent nano-silver particles, so that the nano-silver particles are distributed densely; a great number of hotspot structures are generated; and the SERS effect of the substrate is enhanced. The uniform-height nano-silver SERS active substrate can be prepared simply and quickly with low cost by using the method. The prepared SERS active substrate is convenient to store and carry, and is expected to conduct the high-sensitivity rapid analysis on certain environmental pollutants or food safety contaminants in a laboratory and outdoor fields.

Description

The substrate of a kind of highly homogeneous Nano Silver surface-enhanced Raman scattering activity

Technical field

The invention belongs to the analytical chemistry field, be specifically related at the bottom of a kind of highly homogeneous Nano Silver SERS active group and preparation method thereof.

Background technology

That Surface enhanced raman spectroscopy (SERS) analytic approach has is highly sensitive, detection time short, it is little to disturb, can obtain the advantages such as finger print information of species by the detection molecules vibrational spectrum, context of detection in Surface Science, analysis science and living things system has obtained using widely (Chem. Soc. Rev., 2008,37,885; Chem. Soc. Rev., 2008,37,898).But can SERS move towards practical application, is decided by enhancing, homogeneity and the stability (Mater. Today, 2012,15,16) of SERS substrate to a great extent.Therefore prepare the research focus that remains present SERS field at the bottom of the SERS active group that homogeneity is good, stability is high, enhancement effect is strong.

Research report about substrate preparation is a lot of at present.Mainly concentrate on electrode that noble metal, roughening handle, film etc.Precious metal colloid is to use a class the most extensive, that preparation is the easiest, especially elargol, gold size (Adv. Mater., 2013,25,2056) at the bottom of the active group.Gold and silver nano particle in the colloid can be for the convenient and swift information that provides comparatively accurately, enriches be provided.Though the preparation of the classics of gold size and elargol is fairly simple, form, the aggregation extent of aggregation do not have controllability behind this substrate adding analyte, and the SERS reappearance is also poor.The gold, silver film is the substrate of early adopting in the research, and methods such as electronation deposition commonly used, vacuum moulding machine, electrochemical deposition form active nano-cluster, silver mirror, island film on surfaces such as glass, mica and metals.This preparation method is relatively simple, quick.But its controllability is not strong.Can't guarantee at the bottom of the active group in order, homogeneity, the substrate surface pattern is unordered, influence factor is many, poor reproducibility.Therefore preparation in order controlled substrate be the new focus studied in recent years ( Chem. Sci. , 2011, 2, 1435).

For the explanation of Surface enhanced raman spectroscopy mechanism at present relatively authority be that physics strengthens, we are referred to as " focus " (hot spot) the bigger site of enhancement effect.Focus is in the interstitial site of nano particle, and the gap is of a size of 1-10nm( Nano Lett., 2013, 13(3), 1359).But many self-assembling methods are difficult to accomplish to control the nano particle physical separation, form a large amount of " focus " (J.Phys. Chem. Lett., 2012,3,2303).Therefore this research is devoted to the Surfactant CTAB that to be coupling reagent self-assemble to research on the silicon chip with Nano silver grain, obtains at the bottom of the highly homogeneous Nano Silver SERS active group.

Summary of the invention

The object of the present invention is to provide at the bottom of a kind of highly homogeneous Nano Silver SERS active group and preparation method thereof, can prepare simply, fast, at low cost at the bottom of the highly homogeneous Nano Silver SERS active group.Preservation and easy to carry at the bottom of the SERS active group that makes is expected in the laboratory and the high sensitivity express-analysis is carried out to some environmental contaminants or food security pollutant in outdoor scene.

For achieving the above object, the present invention adopts following technical scheme:

Preparation method at the bottom of a kind of highly homogeneous Nano Silver SERS active group may further comprise the steps:

(1) preparation nano silver colloidal sol: be solvent and reductive agent with polyglycol (PEG), polyvinylpyrrolidone (PVP) is protective agent, AgNO ₃Be the forerunner, adopt chemical reduction method to prepare nano silver colloidal sol; (J. Phys. Chem. C 2010,114,7427 – 7431)

(2) pre-treatment of solid phase substrate: solid phase substrate is immersed in the mixed solution that the concentrated sulphuric acid that volume ratio is 4:1 and massfraction are 30% superoxol, oxidation is carried out on its surface, produce fine and close electronegative silicon hydroxyl;

(3) CTAB self assembly: the solid phase substrate that step (2) was handled immerses in cetyl trimethyl ammonium bromide (CTAB) solution, leaves standstill, and CTAB will be self-assembled into bilayer at substrate surface;

(4) collargol self assembly: have the solid phase substrate of CTAB bilayer to immerse the nano silver colloidal sol of preparation in the step (1) surface-assembled, leave standstill; Nano silver particles self-assembles to the solid phase substrate surface that is adsorbed with the CTAB bilayer by the Electrostatic Absorption method, forms uniform nano silver particles single layer structure;

(5) formation at the bottom of the SERS active group: the solid phase substrate that will be adsorbed with the individual layer nano silver particles is taken out from solution, drying; Because the close and distant water effect of CTAB bilayer, adjacent Nano Silver can be assembled along with the loss of the moisture on surface, thereby forms at the bottom of the highly homogeneous SERS active group of large tracts of land in dry run.

The Nano Silver of preparation is evenly spherical in the described step (1), and particle diameter is 20-100nm.

Solid phase substrate is glass, silicon or earth silicon material in the described step (2).

Oxidization time is 10-30 min in the described step (2).

The concentration of cetyl trimethyl ammonium bromide solution is 0.01-0.1 M in the described step (3).

Time of repose is 60-120min in the described step (3).

Time of repose is 60-180min in the described step (4).

Baking temperature is 20-100 ℃ in the described step (5).

Remarkable advantage of the present invention is:

(1) preparation process is simple, need not expensive reagent and advanced instrument.

(2) homogeneity is strong at the bottom of the prepared SERS active group, is suitable for large-area preparation.

(3) method favorable reproducibility is applicable to that industrialization prepares in enormous quantities.

(4) contain a large amount of SERS " focus " at the bottom of the active group that makes, can be used for developing the high-sensitivity analysis method.

Description of drawings

Fig. 1 is the principle schematic of the active substrate preparation of SERS of the present invention.

Fig. 2 is the TEM phenogram of nano silver colloidal sol.

The SEM phenogram of Fig. 3 at the bottom of for the SERS active group of using the method for the invention preparation.

Embodiment

Embodiment below in conjunction with the preparation method at the bottom of the highly homogeneous Nano Silver SERS of the accompanying drawing narration the present invention active group:

The synoptic diagram of preparation method at the bottom of the highly homogeneous Nano Silver SERS active group of the present invention at first uses the concentrated sulphuric acid and 30% mixed solution of hydrogen peroxide (volume ratio is 4:1) that oxidation is carried out on the solid phase substrate surface as shown in Figure 1.Next will immerse in the CTAB solution through the solid phase substrate that oxidation processes is crossed, leave standstill.CTAB will be self-assembled into bilayer at substrate surface.Then surface-assembled there is the solid phase substrate immersion of CTAB bilayer to contain in the electronegative nano silver colloidal sol in surface, Nano silver grain self-assembles to the solid phase substrate surface that is adsorbed with the CTAB bilayer by the Electrostatic Absorption method, forms uniform nano particle single layer structure.To be adsorbed with the solid phase substrate of individual layer nano silver particles at last at the bottom of being drying to obtain highly homogeneous SERS active group under the proper temperature condition.

Embodiment 1

Following examples illustrate the operating process of using at the bottom of the method for the invention prepares a kind of highly homogeneous Nano Silver SERS active group by reference to the accompanying drawings:

(1) preparation of nano silver colloidal sol

Adopt chemical reduction method to prepare nano silver colloidal sol (J. Phys. Chem. C 2010,114,7427 – 7431).In the PEG of 40mL solution, add the PVP of 444mg, be heated to 80 ℃, treat that solution stirs to clarify after, add the liquor argenti nitratis ophthalmicus of 1mL 0.5M rapidly, continue to add thermal agitation, solution colour by colourless become light yellow.Solution is moved in the teflon reactor of 80mL, be heated to 260 ° of reaction 24h.Characterize to such an extent that mean grain size is 60 nm (Fig. 2) with TEM to it.

(2) at the bottom of the highly homogeneous Nano Silver SERS active group of preparation

Earlier with the concentrated sulphuric acid and 30% mixed solution of hydrogen peroxide (volume ratio is 4:1) oxidation is carried out on solid phase substrate (5*5mm silicon chip) surface, oxidization time is 30min, makes silicon hydroxyl fine and close on the silicon chip surface band.Next the silicon chip that will handle immerses and contains in the solution of 0. 1 M CTAB, leaves standstill 60min, and CTAB will be self-assembled into as shown in Figure 1 bilayer at substrate surface.Then surface-assembled there is the silicon chip of CTAB bilayer to immerse in electronegative Nano Silver (mean grain size 60nm) colloidal sol in surface, leaves standstill 120min.Nano silver grain self-assembles to the solid phase substrate surface that is adsorbed with the CTAB bilayer by the Electrostatic Absorption method, forms uniform nano particle single layer structure.The solid phase substrate that will be adsorbed with the individual layer Nano Silver is dried at ambient temperature at last, obtains at the bottom of the Nano Silver SERS active group of surface elevation homogeneous as shown in Figure 3.

The above only is preferred embodiment of the present invention, and all equalizations of doing according to the present patent application claim change and modify, and all should belong to covering scope of the present invention.

Claims

1. the preparation method at the bottom of the highly homogeneous Nano Silver SERS active group is characterized in that: may further comprise the steps:

(1) preparation nano silver colloidal sol: be solvent and reductive agent with the polyglycol, polyvinylpyrrolidone is protective agent, AgNO ₃Be the forerunner, adopt chemical reduction method to prepare nano silver colloidal sol;

(3) CTAB self assembly: the solid phase substrate that step (2) was handled immerses in the cetyl trimethyl ammonium bromide solution, leaves standstill, and CTAB will be self-assembled into bilayer at substrate surface;

2. the preparation method at the bottom of the highly homogeneous Nano Silver SERS active group according to claim 1 is characterized in that: the Nano Silver of preparation is for evenly spherical in the described step (1), and particle diameter is 20-100nm.

3. the preparation method at the bottom of the highly homogeneous Nano Silver SERS active group according to claim 1 is characterized in that: solid phase substrate is glass, silicon or earth silicon material in the described step (2).

4. the preparation method at the bottom of the highly homogeneous Nano Silver SERS active group according to claim 1 is characterized in that: oxidization time is 10-30 min in the described step (2).

5. the preparation method at the bottom of the highly homogeneous Nano Silver SERS active group according to claim 1 is characterized in that: the concentration of cetyl trimethyl ammonium bromide solution is 0.01-0.1 M in the described step (3).

6. the preparation method at the bottom of the highly homogeneous Nano Silver SERS active group according to claim 1 is characterized in that: time of repose is 60-120min in the described step (3).

7. the preparation method at the bottom of the highly homogeneous Nano Silver SERS active group according to claim 1 is characterized in that: time of repose is 60-180min in the described step (4).

8. the preparation method at the bottom of the highly homogeneous Nano Silver SERS active group according to claim 1 is characterized in that: baking temperature is 20-100 ℃ in the described step (5).

9. at the bottom of the highly homogeneous Nano Silver SERS active group that the method for claim 1 makes.