CN117350087B - Method for obtaining bacterial killing effect and design method of nano-column structure - Google Patents
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- 230000001580 bacterial effect Effects 0.000 title claims abstract description 177
- 238000000034 method Methods 0.000 title claims abstract description 64
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- 238000013461 design Methods 0.000 title abstract description 7
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- 230000001954 sterilising effect Effects 0.000 abstract description 15
- 238000004659 sterilization and disinfection Methods 0.000 abstract description 15
- 241000588724 Escherichia coli Species 0.000 description 12
- 239000002086 nanomaterial Substances 0.000 description 9
- 241000931705 Cicada Species 0.000 description 6
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 206010059866 Drug resistance Diseases 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
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Abstract
The invention relates to the technical field of killing of a nano-column structure for killing bacteria, in particular to a method for acquiring a bacterial killing effect and a method for designing the nano-column structure. Based on the constructed action model between the bacterial object and the reference nano-pillar structure, the interface energy of the action model is obtained, so that the change rate of the interface energy when the bottom of the bacterial object moves towards the vertical inner direction of the nano-pillar is obtained, the change rate of the interface energy caused by the change of the contact angle when the bottom of the bacterial object moves towards the vertical inner direction of the nano-pillar is obtained, and the pushing force of the bacterial object in the moving process of the reference nano-pillar structure and the stress born by the bacterial object in unit area are obtained. The sterilization process of the nano-pillar structure is quantified, so that on one hand, the precise sterilization effect of the nano-pillar structure on bacteria is obtained, and on the other hand, the design of the nano-pillar structure for killing specific bacteria objects is guided.
Description
Technical Field
The invention relates to the technical field of killing of a nano-column structure for killing bacteria, in particular to a method for acquiring a bacterial killing effect and a method for designing the nano-column structure.
Background
The bacteria have strong viability and can cause great harm to the environment, industrial and agricultural production and human health. However, the drug resistance of bacteria to antibiotics is becoming serious, and secondary pollution is brought about by the use of chemical agents, so that the effectiveness of the traditional antibacterial method is not high, and the development of novel antibacterial technology is very important. The initial inspiration comes from the wings of the cicada wings, whose nanopatterned surface induces a bactericidal character with physical effects. Based on the killing of bacteria by cicada wing nanostructures, many studies on surface sterilization of artificial micro-nano structures exist. The first stage is the approach of the bacteria to the surface and contact of the bacteria, and the second stage is the morphological change process of the adhesion of the bacteria to the surface. Nanostructure sterilization occurs in the second stage, and interactions between bacteria and nanomode lead to deformation of cell wall peptidoglycans, leading to catastrophic rupture and subsequent leakage of cell contents and bacterial death. In addition, a great deal of research shows that the geometric parameters of the surface of the nano structure have great influence on the sterilization rate, and the adhesion force of the nano structure to bacteria is the driving force for bacterial deformation death, but the adhesion force of the nano structure for killing bacteria and bacterial deformation until the death failure mechanism is unclear due to the fact that the morphology control of the nano scale and the acting force measurement of the nN scale have great challenges, so that the killing effect of the nano structure to bacteria is difficult to accurately control.
Disclosure of Invention
The technical problem to be solved by the application is to provide a method for obtaining the bacterial killing effectThe design method of the nano-pillar structure has the function of precisely killing bacteria through the nano-pillar structure, and the design of the nano-pillar structure for killing specific bacteria is guided on the basis of clarifying the mechanism of killing bacteria of the nano-pillar structure.
In a first aspect, an embodiment provides a method for obtaining a bacterial killing effect, comprising:
constructing a model of action between a bacterial object and a reference nanopillar structure, the reference nanopillar structure comprising a plurality of nanopillars, the model of action comprising a model that causes the bacterial object to act on the plurality of vertical nanopillars;
acquiring a contact area between a bacterial object and liquid based on the action model as a first contact area, wherein the first contact area comprises the area of the upper surface of a cylindrical part of the bacterial object, the area of the upper surface of a circular part of the bacterial object and the contact area of the bottom of the bacterial object and the liquid;
acquiring a contact area between the bacterial object and the nano column based on the action model as a second contact area;
acquiring the contact area between the nano column and the liquid based on the action model as a third contact area;
obtaining a stress tensor between the bacterial object and the liquid as a first stress tensor, a stress tensor between the bacterial object and the nano-pillar as a second stress tensor, and an interfacial tension between the liquid and the nano-pillar structure;
acquiring the interface energy of the action model based on the first contact area, the second contact area, the third contact area, the first stress tensor, the second stress tensor and the interface tension between the liquid and the nano-pillar structure;
based on the interface energy, acquiring a change rate of the interface energy when the bottom of the bacterial object moves towards the vertical inner direction of the nano column as a first change rate, acquiring a change rate of the interface energy caused by contact angle change when the bottom of the bacterial object moves towards the vertical inner direction of the nano column as a second change rate, and acquiring a change rate of the contact angle when the bottom of the bacterial object moves towards the vertical inner direction of the nano column as a third change rate;
acquiring the driving force of the bacterial object in the moving process of the reference nano-pillar structure based on the first change rate, the second change rate and the third change rate;
based on the driving force of the bacterial object in the moving process to the reference nano-pillar structure, obtaining the stress born by the bacterial object in a unit area;
and acquiring the killing effect of the reference nano-pillar structure on the bacterial object based on the stress applied to the bacterial object in unit area.
In one embodiment, the step of obtaining the contact area between the bacterial object and the liquid based on the action model as a first contact area, where the first contact area includes an area of an upper surface of a cylindrical portion of the bacterial object, an area of an upper surface of a circular portion of the bacterial object, and a contact area between a bottom of the bacterial object and the liquid, includes:
（3）
（4）
（5）
（6）
wherein,representing the first contact area->Representing the area of the upper surface of the cylindrical part of the bacterial object, < + >>Represents the area of the upper surface of the circular segment of the bacterial object, < >>Representing the contact area of the bottom of the bacterial object with the liquid;Lrepresenting the length of the cylindrical portion of the bacterial object, based on the type of bacterial object;Rrepresenting the radius of the cylindrical portion of the bacterial object, based on the type of bacterial object;θrepresenting the contact angle of the bacterial object with the nanopillar;hrepresenting the depth of the nanopillars into the bacterial object;r s representing half of the width of the rectangular bottom surface of the bacteria object adhered to the nano column, and measuring based on the action model;indicating the height of the two-headed sphere of the bacterial subject;
then there are:
（7）
wherein,frepresenting the fraction of solid area of the nanopillars,；drepresenting the diameter of the nanopillar;prepresenting the center-to-center distance between adjacent nanopillars.
In one embodiment, the step of obtaining the contact area between the bacterial object and the nano-pillar based on the action model as the second contact area includes:
（8）
wherein,A cs representing a second contact area.
In one embodiment, the step of obtaining the contact area between the nano-pillar and the liquid based on the action model as the third contact area includes:
（9）
wherein,representing a third contact area, a represents a selected area of the action model that optionally contains a single bacterial object.
In one embodiment, the step of obtaining the stress tensor between the bacterial object and the liquid as a first stress tensor, the stress tensor between the bacterial object and the nano-pillar as a second stress tensor, and the interfacial tension between the liquid and the nano-pillar structure comprises:
（11）
（12）
（13）
wherein,indicating the interfacial tension of liquid and air, +.>；/>Representing a first stress tensor->Representing a second stress tensor->Representing interfacial tension between the liquid and the nanopillar structure; />Representing the intrinsic contact angle of the liquid drop and the reference nano-pillar structure material, and obtaining the intrinsic contact angle based on the rough characteristic of the material surface; />The intrinsic contact angle of the bacterial object and the nano-pillar structure material is expressed and obtained through experimental measurement.
In one embodiment, the obtaining the interface energy of the action model based on the first contact area, the second contact area, the third contact area, the first stress tensor, the second stress tensor, and the interfacial tension between the liquid and the nano-pillar structure includes:
（2）
wherein,Erepresenting the interfacial energy of the model of action.
In one embodiment, the step of obtaining, based on the interface energy, a change rate of the interface energy when the bottom of the bacterial object moves toward the vertical inner direction of the nano-pillar as a first change rate, obtaining, as a second change rate, a change rate of the interface energy due to a change in a contact angle when the bottom of the bacterial object moves toward the vertical inner direction of the nano-pillar, and obtaining, as a third change rate, a change rate of the contact angle when the bottom of the bacterial object moves toward the vertical inner direction of the nano-pillar includes:
（15）
（16）
（23）
wherein,representing a first rate of change,/->Representing a second rate of change,/->Indicating a third rate of change.
In one embodiment, the obtaining the driving force of the bacterial object moving towards the reference nano-pillar structure based on the first change rate, the second change rate and the third change rate includes:
（25）
wherein,Frepresenting the driving force of the bacterial object moving towards the reference nano-pillar structure.
In one embodiment, the step of obtaining the stress applied to the bacterial object in a unit area based on the pushing force of the bacterial object moving towards the reference nano-pillar structure includes:
（26）
wherein,Prepresenting the stress to which a bacterial object is subjected per unit area.
In a second aspect, an embodiment provides a method for designing a structure of a bacteria killing nano-pillar, where the method is based on stress applied to a unit area of a bacterial object obtained by the method for obtaining a bacteria killing effect according to any one of the embodiments, and the method is used for designing a nano-pillar structure having a killing capability for a specific bacterial object.
The beneficial effects of the invention are as follows:
the sterilization process of the nano-pillar structure is quantified, so that the problem that the driving force and stress of bacteria on the nano-pillar structure are difficult to obtain is solved, and whether the stress has a sterilization effect on the bacteria is conveniently judged, so that the precise sterilization effect of the nano-pillar structure on the bacteria is obtained, and the design of the nano-pillar structure for killing specific bacterial objects is guided.
Drawings
FIG. 1 is a schematic front view of a model of action of an embodiment of the present application;
FIG. 2 is a schematic side view of a model of action of an embodiment of the present application;
FIG. 3 is a schematic flow chart of a method for obtaining a bacterial kill effect according to an embodiment of the present application.
Detailed Description
The invention will be described in further detail below with reference to the drawings by means of specific embodiments. Wherein like elements in different embodiments are numbered alike in association. In the following embodiments, numerous specific details are set forth in order to provide a better understanding of the present application. However, one skilled in the art will readily recognize that some of the features may be omitted, or replaced by other elements, materials, or methods in different situations. In some instances, some operations associated with the present application have not been shown or described in the specification to avoid obscuring the core portions of the present application, and may not be necessary for a person skilled in the art to describe in detail the relevant operations based on the description herein and the general knowledge of one skilled in the art.
Furthermore, the described features, operations, or characteristics of the description may be combined in any suitable manner in various embodiments. Also, various steps or acts in the method descriptions may be interchanged or modified in a manner apparent to those of ordinary skill in the art. Thus, the various orders in the description and drawings are for clarity of description of only certain embodiments, and are not meant to be required orders unless otherwise indicated.
The numbering of the components itself, e.g. "first", "second", etc., is used herein merely to distinguish between the described objects and does not have any sequential or technical meaning.
For convenience of explanation of the inventive concept of the present application, a brief explanation of a bacteria killing technique of the nano-pillar structure is provided below.
The adhesion of the nano-pillar structure to bacteria is a driving force for bacterial deformation and death, while the geometric parameters of the surface of the nano-pillar structure have great influence on the adhesion of bacteria, and the adhesion of the nano-pillar structure for killing bacteria and the mechanism of bacterial deformation until death is damaged are unclear because of the extremely challenges of morphology control of nano-scale and force measurement of nN scale, so that the killing effect of the nano-pillar structure on bacteria is difficult to accurately control.
According to the invention, a mathematical model of bacteria in the nano-pillar structure is built by using a stress model of liquid drops moving inwards on the nano-pillar array, so that the specific driving force (i.e. adhesive force) of the nano-pillar structure to the bacteria is revealed, the stress born by the unit area of the bacteria is further obtained, and whether the stress has a killing effect on the bacteria is judged, so that the accurate killing effect of the nano-pillar structure to the bacteria is obtained.
From an interfacial energy perspective, there is an interfacial energy relationship between bacteria in a liquid and a material. The interfacial energy relationship includes interfacial energy between bacteria and liquid, interfacial energy between bacteria and nanopillar structures, interfacial energy between nanopillar structures and liquid. The nano-pillar structure has higher surface energy, and the surface with high surface energy can attract micro-particles to the surface, so that the surface energy is reduced, and in order to conveniently study the killing effect of the nano-pillar structure on bacteria, in the application, firstly, an action model between a bacterial object and the reference nano-pillar structure is constructed based on the known reference nano-pillar structure, and the action model is shown in fig. 1 and 2. The action model reflects the acting force of the material on the bacterial object through the gradient of the interface energy.
The surface energy caused by deformation of the surface of the object includes two types, one is the free energy of the Gibbs surface in thermodynamics and the other is the surface energy caused by stress change. The former is called surface free energy, denoted by gamma; the latter is called the deformation free energy and is denoted by sigma.
The energy gradient is a driving force and the object can be moved from a high energy position to a lower energy position. For the above action model, the gradient of the interface energy between the bacterial object and the surface of the reference nano-pillar structure is the driving force of downward movement of the bacterial object, and can be usedFRepresenting, i.e., the impetus of the research of the present applicationFThe following steps are:
（1）
wherein,Erepresenting the interfacial energy between the bacterial object and the reference nanopillar structure,hindicating the depth of the nanopillar into the bacterial object, i.e., the distance the bacterial object moves toward the nanopillar.
In the action model, the interfaces involved are the interfaces between bacteria and liquid, between bacteria and nano-pillars, and between nano-pillars and liquid, so the expression of interfacial energy can be as follows
（2）
Wherein,Erepresenting interface energy of the action model;representing the contact surface between the bacterial object and the liquid, i.e. the first contact area; />Representing the contact area between the bacterial object and the nanopillar, i.e., the second contact area; />Representing the contact area between the nanopillar and the liquid, i.e., the third contact area; />Indicating, i.e. first stress tensor,/->Indicating, i.e. the second stress tensor,/->Indicating the interfacial tension between the liquid and the nanopillar structure.
Referring to FIG. 1, for example, E.coli is divided into middle cylindrical portions (longL（LSpherical bacteria when 0), radiusR) And a two-headed segment (radius)RHigh heightH Ball segment ) The adhesion bottom surface of bacteria and nano-pillars is regarded as the middle length L and width 2r s Has a rectangular shape with two end bottoms having a radius ofr s Is set as the contact angle of bacteria and materialθThe depth of the nano-pillars entering the bacteria ishBacteria andthe contact area between the liquids is:
（3）
wherein,representing the area of the upper surface of the cylindrical part of the bacterial object, < + >>Represents the area of the upper surface of the circular segment of the bacterial object, < >>Indicating the contact area of the bottom of the bacterial object with the liquid. In one embodiment, the liquid herein may be water.
And also has
（4）
（5）
（6）
Thus, substitution of formulas (4), (5), (6) into formula (3) can be obtained:
（7）
wherein,frepresenting the fraction of solid area of the nanopillar,；drepresenting the diameter of the nanopillar;prepresenting the center-to-center distance between adjacent nanopillars.
Similarly, a second contact area can be obtainedA cs And a third contact areaThe method comprises the following steps of:
（8）
（9）
wherein,Arepresenting any selected area of the model of action that contains a single bacterial object.
Substituting the formulas (7), (8) and (9) into the formula (2) to obtain a specific expression of the system interface energy
（10）
And due to
（11）
（12）
（13）
Wherein,indicating the interfacial tension of liquid and air, +.>；/>Representing the intrinsic contact angle of the liquid drop and the reference nano-pillar structure material, and obtaining the intrinsic contact angle based on the rough characteristic of the material surface; />The intrinsic contact angle of the bacterial object and the nano-pillar structure material is expressed and obtained through experimental measurement.
Thus, two variables in equation (10) can be obtained,handθthen equation (1) can be expressed as
（14）
Wherein,representing a first rate of change,/->Representing a second rate of change,/->Indicating a third rate of change.
Based on equation (10), it can be obtained:
（15）
（16）
for a third rate of changeIt is necessary to derive it by differentiation of the volumetric expression of the bacterial object. Referring to FIG. 1, the volume of a bacterial object above a nanopillarV Upper part Consists of two parts, one part is the volume of the bacterial cylinder part above the upper surface of the nano-columnV Cylinder column Part of the spheres are bacteria objects above the upper surface of the nano columnVolume of the missing partV Ball segment . For the followingV Cylinder column AndV ball segment And also have
（17）
（18）
Therefore, there are
（19）
While the volume of bacterial objects under the nanopillarsV Lower part(s) Has the following components
（20）
By combining the formula (19) and the formula (20), the volume of the bacterial object scope nano-column can be obtained
（21）
Differentiating the formula (21) is:
（22）
obtaining:
（23）。
bringing equations (15), (16) and (23) into equation (14) yields
（24）。
Then there is
（25）。
Will beWith the equation (25), there is
（26）
Wherein,Prepresenting the stress to which a bacterial object is subjected per unit area.
Thus, referring to FIG. 3, we can obtain a method for obtaining a bacterial kill comprising:
step S10, constructing a model of action between the bacterial object and a reference nanopillar structure, the reference nanopillar structure comprising a plurality of nanopillars, the model of action comprising a model of causing the bacterial object to act on the plurality of vertical nanopillars.
Step S20, acquiring the contact area between the bacterial object and the liquid based on the action model as a first contact area, wherein the first contact area comprises the area of the upper surface of the cylindrical part of the bacterial object, the area of the upper surface of the round part of the bacterial object and the contact area of the bottom of the bacterial object and the liquid.
In one embodiment, the method comprises the steps of:
（3）
（4）
（5）
（6）
wherein,representing the first contact area->Representing the area of the upper surface of the cylindrical part of the bacterial object, < + >>Represents the area of the upper surface of the circular segment of the bacterial object, < >>Representing the contact area of the bottom of the bacterial object with the liquid;Lrepresenting the length of the cylindrical portion of the bacterial object, based on the type of bacterial object;Rrepresenting the radius of the cylindrical portion of the bacterial object, based on the type of bacterial object;θrepresenting the contact angle of the bacterial object with the nanopillar;hrepresenting the depth of the nanopillars into the bacterial object;r s representing half of the width of the rectangular bottom surface of the bacteria object adhered to the nano column, and measuring based on an action model;H ball segment Indicating the height of the two-headed sphere of the bacterial subject;
then there are:
（7）
wherein,frepresenting the fraction of solid area of the nanopillar,；drepresenting the diameter of the nanopillar;prepresenting the center-to-center distance between adjacent nanopillars.
Step S30, acquiring the contact area between the bacterial object and the nano-column as a second contact area based on the action model.
In one embodiment, the method comprises the steps of:
（8）
wherein,A cs representing a second contact area.
Step S40, the contact area between the nano-column and the liquid is obtained as a third contact area based on the action model.
In one embodiment, the method comprises the steps of:
（9）
wherein,representing a third contact area, a represents a selected area of the action model that optionally contains a single bacterial object.
Step S50, obtaining a stress tensor between the bacterial object and the liquid as a first stress tensor, a stress tensor between the bacterial object and the nano-pillar as a second stress tensor, and an interfacial tension between the liquid and the nano-pillar structure.
In one embodiment, the method comprises the steps of:
（11）
（12）
（13）
wherein,indicating the interfacial tension of liquid and air, +.>；/>Representing a first stress tensor->Representing a second stress tensor->Representing interfacial tension between the liquid and the nanopillar structure; />The intrinsic contact angle representing the reference nanopillar structure, obtained based on the roughness characteristics of the material surface; />The contact angle of a bacterial object is indicated and obtained by experimental measurement.
Step S60, obtaining the interface energy of the action model based on the first contact area, the second contact area, the third contact area, the first stress tensor, the second stress tensor and the interface tension between the liquid and the nano-pillar structure.
In one embodiment, the method comprises the steps of:
（2）
wherein,Erepresenting the interfacial energy of the model of action.
Step S70, based on the interface energy, acquiring the change rate of the interface energy when the bottom of the bacterial object moves towards the vertical inner direction of the nano column as a first change rate, acquiring the change rate of the interface energy caused by the change of the contact angle when the bottom of the bacterial object moves towards the vertical inner direction of the nano column as a second change rate, and acquiring the change rate of the contact angle when the bottom of the bacterial object moves towards the vertical inner direction of the nano column as a third change rate.
In one embodiment, the method comprises the steps of:
（15）
（16）
（23）
wherein,representing a first rate of change,/->Representing a second rate of change,/->Indicating a third rate of change.
Step S80, based on the first change rate, the second change rate and the third change rate, the driving force of the bacteria object moving to the reference nano-pillar structure is obtained.
In one embodiment, the method comprises the steps of:
（25）
wherein,Fthe driving force of the bacterial object moving towards the reference nano-pillar structure is represented.
Step S90, based on the pushing force of the bacterial object in the moving process of the bacterial object to the reference nano-pillar structure, the stress applied to the bacterial object in a unit area is obtained.
In one embodiment, the method comprises the steps of:
（26）
wherein,Prepresenting the stress to which a bacterial object is subjected per unit area.
During the interaction of the bacterial object with the reference nanopillar structure,θis varied and corresponds toFAndPalso vary, according toθSize knowingFAndPfor a given nanopillar structure and bacteria,θthe maximum stress value in the process of the bacteria and the nano-pillar structure can be known by knowing a range. For the final stable state of the effect of bacteria and the nano-pillar structure, the contact angle of the bacteria and the nano-pillar can also be directly measured through experimentsθ。
When the height of the nano-pillars is greater than the diameter of the bacteria, i.eH＞2R，θThe maximum range is 0 < θ < 180 °.
When the height of the nanopillars is less than half the diameter of the bacteria, i.eH＜R，θThe maximum range is less than 90 degrees and less than arccoss [ (]H-R)/R]＜θ＜180°。
When the height of the nano-pillars is greater than half the diameter of the bacteria and less than the diameter of the bacteria, i.e.R＜H＜2R，θThe maximum range is arccoss [ (], aH-R)/R]＜θ< 180 DEG, at this time arccos [ (]H-R)/R]＜90°。
For example, a nano-pillar having a reference nano-pillar structure using PC1 as a nano-nanomaterialH=150nm，d=60nm，PThe intrinsic contact angle of the reference nanopillar structure was experimentally measured with E.coli (E.coli) as the bacterial target and water as the liquid =170 nmIntrinsic contact angle of bacterial object with nano-pillar structure material of 119 DEG +.>120 °, then it is calculated that: />=6.60051E-08、/>=1.46218E-07、/>= 1.60426E-07. Due toH＜RThenθThe calculated range is 120 DEG to 180 DEG, and F is calculated to be the maximum valueθWhen=120°, f=60.6nn and p=0.66 MPa are calculated.
Step S100, the killing effect of the reference nano-pillar structure on the bacterial object is obtained based on the stress received by the bacterial object in unit area.
When the stress applied to the bacterial object in unit area reaches 1MPa, the nano-pillar structure has a killing effect on the bacterial object.
The method quantifies the sterilization process of the nano-pillar structure, solves the problem that the pushing force and stress of bacteria on the nano-pillar structure are difficult to obtain, and is convenient to judge whether the stress has a sterilization effect on the bacteria, so that the precise sterilization effect of the nano-pillar structure on the bacteria is obtained.
Referring to table 1, the driving force and stress calculated based on the respective methods are compared with the experimental results of some documents.
TABLE 1
| Materials in the literature | Material parameters (nm) in the literature | Bacterial parameters in literature (um) | Bacterial types in literature | Sterilization rate in literature | The driving force (nN) calculated by the method | Stress (MPa) calculated by the method |
| PC1 | H=150；D=60；P=170 | L=1.8，R=0.3 | E.coli | 3% | 60.6 | 0.66 |
| PC2 | H=200；D=60；P=170 | L=1.8，R=0.3 | E.coli | 93% | 95.5 | 1.04 |
| PC3 | H=300；D=60；P=170 | L=1.8，R=0.3 | E.coli | 98% | 116 | 1.26 |
| PC4 | H=400；D=60；P=170 | L=1.8，R=0.3 | E.coli | 98% | 116 | 1.26 |
| PC5 | H=310；D=60；P=170 | L=1.8，R=0.3 | E.coli | 98% | 116 | 1.26 |
| PMMA1 | H=300；D=190；P=320 | L=3，R=0.4 | E.coli | 20% | Negative pole | Negative pole |
| PMMA2 | H=210；D=70；P=170 | L=3，R=0.4 | E.coli | 21% | 131 | 0.52 |
| Cicada wings 1 | H=210；D=60；P=210 | L=3，R=0.4 | E.coli | 100% | 455 | 4.7 |
| Cicada wings 2 | H=210；D=60；P=210 | L=2，R=0.3 | P.aeruginosa | 100% | 363 | 5.37 |
| Cicada wings 3 | H=200；D=60；P=170 | L=3，R=1 | S.cerevisiae | 100% | 130nN | 1.61 |
| Ormostamp1 | H=400；D=80；P=170 | R=1 | S.aureus | 100% | 61nN | 2.28 |
| Ormostamp2 | H=250；D=80；P=130 | R=1 | S.aureus | 31% | Negative pole | Negative pole |
By comparison, we found that:
first, the size of the adhesion force to which bacteria are subjected is on the scale of several tens of nN to several hundreds of nN.
Secondly, the elastic limit stress of the escherichia coli is 1MPa, and in the calculation result, the calculation stress corresponding to the large experimental sterilization rate is larger than 1MPa. The stress calculated for the small sterilization rate is less than 1MPa or is negative.
Third, the PC1-PC5,5 sets of data are highly different. When the heights H of the PC1 and PC2 nano-pillars are smaller than r=300 nm, bacteria are deformed to the bottom process due to the fact that the nano-pillar heights are too low, and penetration cannot be continued. arccos [ (H-R)/R ] < θ < 180 °, θ does not contain 90 °, where the maximum value of F and P is related to arccos [ (H-R)/R ]. I.e., F is related to P and the nano-pillar height. H=200 nm this process calculates the maximum stress to which the bacteria are subjected to be 1.04MPa; h=150 nm this procedure calculates the maximum stress to which the bacteria are subjected to be 0.66MPa.
When the heights H of the PC3, PC4 and PC5 nano-pillars are more than or equal to 300nm, arccos [ (H-R)/R ] < θ < 180 degrees, and θ ranges from less than 90 degrees to 180 degrees, and the maximum value is near 90 degrees and is irrelevant to arccos [ (H-R)/R ], namely F, P is irrelevant to the heights. And the experimental sterilization rates of the three structural materials are consistent, and the maximum stress of bacteria is 1.26MPa according to the calculation result of the model.
Fourth, in addition to PC material comparison conforming to model calculations, natural material cicada wings, some artificially prepared nanomaterials also conform to model calculations, but are limited to satisfying the model-like nanopillar geometry.
In summary, we can get that the parameters of the effect of the nano-pillar structure on bacterial killing calculation are larger diameter, distance, ratio of diameter to distance, and diameter of bacteria.
In view of this, in one embodiment of the present application, a design method for a bacteria killing nano-pillar structure is provided, and a nano-pillar structure having a killing capability for a specific bacterial object is designed based on stress applied to a bacterial object per unit area obtained by the bacteria killing effect obtaining method in any one of the above embodiments, including a diameter, a pitch, and a ratio of the diameter to the pitch of the nano-pillar.
An embodiment of the present application provides a computer readable storage medium having a program stored thereon, where the stored program includes a method that can be loaded by a processor and processed in any of the above embodiments.
Those skilled in the art will appreciate that all or part of the functions of the various methods in the above embodiments may be implemented by hardware, or may be implemented by a computer program. When all or part of the functions in the above embodiments are implemented by means of a computer program, the program may be stored in a computer readable storage medium, and the storage medium may include: read-only memory, random access memory, magnetic disk, optical disk, hard disk, etc., and the program is executed by a computer to realize the above-mentioned functions. For example, the program is stored in the memory of the device, and when the program in the memory is executed by the processor, all or part of the functions described above can be realized. In addition, when all or part of the functions in the above embodiments are implemented by means of a computer program, the program may be stored in a storage medium such as a server, another computer, a magnetic disk, an optical disk, a flash disk, or a removable hard disk, and the program in the above embodiments may be implemented by downloading or copying the program into a memory of a local device or updating a version of a system of the local device, and when the program in the memory is executed by a processor.
The foregoing description of the invention has been presented for purposes of illustration and description, and is not intended to be limiting. Several simple deductions, modifications or substitutions may also be made by a person skilled in the art to which the invention pertains, based on the idea of the invention.
Claims (10)
1. A method for obtaining a bacterial killing effect, comprising:
constructing a model of action between a bacterial object and a reference nanopillar structure, the reference nanopillar structure comprising a plurality of nanopillars, the model of action comprising a model that causes the bacterial object to act on the plurality of vertical nanopillars;
acquiring a contact area between a bacterial object and liquid based on the action model as a first contact area, wherein the first contact area comprises the area of the upper surface of a cylindrical part of the bacterial object, the area of the upper surface of a circular part of the bacterial object and the contact area of the bottom of the bacterial object and the liquid;
acquiring a contact area between the bacterial object and the nano column based on the action model as a second contact area;
acquiring the contact area between the nano column and the liquid based on the action model as a third contact area;
obtaining a stress tensor between the bacterial object and the liquid as a first stress tensor, a stress tensor between the bacterial object and the nano-pillar as a second stress tensor, and an interfacial tension between the liquid and the nano-pillar structure;
acquiring the interface energy of the action model based on the first contact area, the second contact area, the third contact area, the first stress tensor, the second stress tensor and the interface tension between the liquid and the nano-pillar structure;
based on the interface energy, acquiring a change rate of the interface energy when the bottom of the bacterial object moves towards the vertical inner direction of the nano column as a first change rate, acquiring a change rate of the interface energy caused by contact angle change when the bottom of the bacterial object moves towards the vertical inner direction of the nano column as a second change rate, and acquiring a change rate of the contact angle when the bottom of the bacterial object moves towards the vertical inner direction of the nano column as a third change rate;
acquiring the driving force of the bacterial object in the moving process of the reference nano-pillar structure based on the first change rate, the second change rate and the third change rate;
based on the driving force of the bacterial object in the moving process to the reference nano-pillar structure, obtaining the stress born by the bacterial object in a unit area;
and acquiring the killing effect of the reference nano-pillar structure on the bacterial object based on the stress applied to the bacterial object in unit area.
2. The method for acquiring a bacterial killing effect according to claim 1, wherein the step of acquiring a contact area between the bacterial object and the liquid based on the action model as a first contact area including an area of an upper surface of the cylindrical portion of the bacterial object, an area of an upper surface of the circular portion of the bacterial object, and a contact area of a bottom portion of the bacterial object with the liquid includes:
（3）
（4）
（5）
（6）
wherein,representing the first contact area->Representing the area of the upper surface of the cylindrical part of the bacterial object, < + >>Represents the area of the upper surface of the circular segment of the bacterial object, < >>Representing the contact area of the bottom of the bacterial object with the liquid; l represents the length of the cylindrical portion of the bacterial object, obtained based on the type of bacterial object; r represents the radius of the cylindrical portion of the bacterial object, derived based on the type of bacterial object; θ represents the contact angle of the bacterial object with the nanopillar; h represents the depth of the nano-pillars into the bacterial object; r is (r) s Representing half of the width of the rectangular bottom surface of the bacteria object adhered to the nano column, and measuring based on the action model; h Ball segment Indicating the height of the two-headed sphere of the bacterial subject;
then there are:
（7）
wherein f represents the solid area fraction of the nanopillar,the method comprises the steps of carrying out a first treatment on the surface of the d represents the diameter of the nanopillar; p represents the center distance between adjacent nanopillars.
3. The method for acquiring bacterial kill of claim 2, wherein the step of acquiring the contact area between the bacterial object and the nano-column based on the action model as the second contact area comprises:
（8）
wherein A is cs Representing a second contact area.
4. The method for acquiring a bacterial killing effect according to claim 3, wherein the step of acquiring a contact area between the nano-pillars and the liquid based on the effect model as a third contact area comprises:
（9）
wherein,representing a third contact area, a representing a selected area of the interaction model that optionally contains a single bacterial object, and H representing the height of the nanopillar.
5. The method of claim 4, wherein the step of obtaining the stress tensor between the bacterial object and the liquid as the first stress tensor, the stress tensor between the bacterial object and the nano-pillars as the second stress tensor, and the interfacial tension between the liquid and the nano-pillar structures comprises:
（11）
（12）
（13）
wherein,indicating the interfacial tension of liquid and air, +.>；/>Representing a first stress tensor->Representing a second stress tensor->Representing interfacial tension between the liquid and the nanopillar structure; />Representing the intrinsic contact angle of the liquid drop and the reference nano-pillar structure material, and obtaining the intrinsic contact angle based on the rough characteristic of the material surface; />Indicating the intrinsic contact angle of the bacterial object with the nano-pillar structured material,obtained by experimental measurements.
6. The method of claim 5, wherein the step of obtaining the interface energy of the action model based on the first contact area, the second contact area, the third contact area, the first stress tensor, the second stress tensor, and the interfacial tension between the liquid and the nano-pillar structure comprises:
（2）
wherein E represents the interfacial energy of the model of action.
7. The method of obtaining a bacterial killing according to claim 6, wherein the obtaining, based on the interfacial energy, a change rate of interfacial energy when the bottom of the bacterial object moves toward the inside of the nano-pillar as a first change rate, a change rate of interfacial energy due to a change in contact angle when the bottom of the bacterial object moves toward the inside of the nano-pillar as a second change rate, and a change rate of contact angle when the bottom of the bacterial object moves toward the inside of the nano-pillar as a third change rate includes:
（15）
（16）
（23）
wherein,representing a first rate of change,/->Representing a second rate of change,/->Indicating a third rate of change.
8. The method of claim 7, wherein the step of obtaining the driving force of the movement of the bacterial object to the reference nanopillar structure based on the first rate of change, the second rate of change, and the third rate of change comprises:
（25）
wherein F represents the driving force of the bacterial object moving toward the reference nanopillar structure.
9. The method of claim 8, wherein the step of obtaining the stress applied to the bacterial object per unit area based on the pushing force of the bacterial object moving toward the reference nano-pillar structure comprises:
（26）
wherein P represents the stress to which the bacterial object is subjected per unit area.
10. A method for designing a bacteria-killing nano-pillar structure, characterized in that a nano-pillar structure having a killing ability for a specific bacterial object is designed based on stress received by a bacterial object per unit area obtained by the bacteria-killing-action obtaining method according to any one of claims 1 to 9.
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