CH703612B1 - Process for coating hydrophilic solids with a gold layer with extensive surface and a gold layer having a surface coated with an extended hydrophilic solid. - Google Patents

Abstract

The invention relates to a process for coating hydrophilic solids with a gold surface with extensive surface, comprising immersing the surface of the solid in a reaction solution containing gold ions and hydroxylamine, characterized in that the reaction solution consists of the following constituents: Water,? first constituent selected from the group consisting of tetrachloroauric acid HAuCl 4, salts of this acid and mixtures thereof; second component selected from the group comprising hydroxylamine, its salts and mixtures thereof. The invention also encompasses a hydrophilic solid coated with a gold extended-area solid produced by this method.

Description

The invention relates to a method for coating the surfaces of hydrophilic solids (metals, semiconductors and dielectrics), in particular silicon, glass, indium-tin oxide (ITO), aluminum and gallium nitride, with a gold layer comprising structures with a greatly extended surface, hereinafter Nano-flowers »or« micro-flowers »called.

The descriptions of the gold structures, the folded or frayed shape reminiscent of flowers (flower -like gold particles, gold nanoflowers, gold microflowers), have appeared only a few years ago in the scientific literature. The processes that allow to obtain gold coating of the surfaces are guided on electrodes. As a result of electrodeposition, the nanoparticles formed after reduction of the gold ions precipitate either directly on the electrode surface in the form of nanosheets [Hui-Hong Liu, Ying Liang, Hua-Jun Liu, Electrochimica Acta, 2009, 54, 75144; Yin Li, Gaoquan Shi, The Journal of Physical Chemistry B, 2005, 109, 23787], or as spherical particles which convert to the flowers in the presence of the reaction mixture [Ashok Kumar Das, C. Retna Raj, Journal of Electroanalytical Chemistry, 2010, 638, 189]. Most publications relate to the synthesis of golden nano- or microblooms in solution. The source of the gold cations is usually the tetrachloroauric acid (HAuCl 4) or its salts; other reagents present in the reaction mixture in precisely adjusted concentrations are responsible for the formation of the frayed, flower-like structures. These may include u.a. be selected polymers, e.g. Polyaniline [P. R. Sajanlal, T.S. Sreeprasad, A. Sreekumaran Nair, T. Pradeep, Langmuir, 2008, 24, 4607] or Chitosan [Wei Wang, Hua Cui, The Journal of Physical Chemistry C, 2008, 112, 10759; Wei Wang, Xuan Yang, Hua Cui, The Journal of Physical Chemistry C, 2008, 112, 16348], or blistering surfactants within which the golden flower-like structures are formed [Ling Zhong, Xiaodong Zhai, Xuefeng Zhu, Pingping Yao, Minghua Liu, Langmuir, 2010, 26 (8), 5876; Haolong Li, Yang Yang, Yizhan Wang, Wen Li, Lihua Bi, Lixin Wu, Chemical Communications, 2010, 46, 3750]. The reaction is also carried out in the presence of DNA to obtain the gold blossoms [Zidong Wang, Jieqian Zhang, Jonathan M. Ekman, Paul JA Kenis, Yi Lu, Nano Letters, 2010, 10, 1886] or the effect of UV radiation to the mixture containing HAuCl4, silver ions and polyvinylpyrrolidone, followed by centrifugation, whereby the resulting nanoparticles form the flower-like aggregates [Li Wang, Gang Wei, Cunlan Guo, Lanlan Sun, Yujing Sun, Yonghai Song, Tao Yang, Zhuang Li, Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2008, 312, 148].

The presented methods for synthesizing the golden nano- and microblooms are in most cases multi-step processes that require prior synthesis of the gold nanoparticles and use of numerous reagents. In addition, there are methods that allow production of folded gold particles in solution, in the coating of the surfaces with these methods, however, the application of electrodeposition was necessary. These processes, in which the gold cations are reduced with hydroxylamine, similar to the present invention, require the use of precursor nanoparticles as well as additional reagents; they are also multi-level processes.

The structures obtained by the method according to the invention can be used as so-called substrates for measurements of surface-enhanced Raman scattering (SERS). This is a spectroscopic technique that is based on the measurement of light intensity from the ultraviolet, visible and near infrared spectral regions, where the light is inelastic to those on the surface of some metals (eg Ag, Au or Cu) with nanometer surface roughnesses (10-100nm ) is adsorbed on adsorbed molecules [K. Kneipp, H. Kneipp, I. Itzkan, R.R. Dasari, M.S. Feld, Phys. Rev. Lett., 78 (1997) 1667; S.Nie, S.R. Emory, Science, 275 (1997) 1102]. SERS is one of the fastest developing spectroscopic techniques in the last decade, as it increases the effective Raman cross-section of the molecules adsorbed on the metal surface by a few orders of magnitude (10 <2> -10 <6>, and even 10 <for some systems 8> -10 <15> [K. Kneipp, H. Kneipp, I. Itzkan, RR Dasari, MS Feld, Phys., Rev. Lett., 78 (1997) 1667; S. Nie, SR Emory, Science, 275 ( 1997) 1102]) compared to the effective Raman cross section of the non-adsorbed molecules [M. Herne, A.M. Ahem, R.L. Garreil, J. Am. Chem. Soc., 113 (1991) 846; J. Thornton, R.K. Force, Appl. Spectrosc., 45 (1991) 1522].

The amplification of the SERS signal depends on a number of the factors, including the effective Raman cross section, the frequency of the excitation radiation, the chemical origin of the molecule, but especially the nature of the metal substrate on which the molecule adsorbed, and its roughness degree. These roughnesses, or irregularities, are responsible for the electromagnetic mechanism of the amplification, which is the dominating amplification mechanism of the SERS [P. Kambhampati, C.M. Child, M.C. Foster, A. Campion, J. Chem. Phys., 108 (1998) 5013].

The inclusion of the SERS spectra in the presence of gold particles with a correspondingly folded surface allows to obtain good signal amplification factors. For various flower-like gold particles presented in the literature, which differ in dimensions and surface morphology, their utility in spectroscopic analysis has been demonstrated [Jianping Xie, Qingbo Zhang, Jim Yang Lee, Daniel IC Wang, ACS Nano, 2008, 2 (12), 2473; Bikash Kumar Jena, C. Retna Raj, Chemistry of Materials, 2008, 20, 3546; Ju-Hyun Kim, Taejoon Kang, Seung Min Yoo, Sang Yup Lee, Bongsoo Kim, Yang-Kyu Choi, Nanotechnology, 2009, 20, 235302]. The golden nanosheets offered better amplification factors for SERS than the nanosheets and porous structure made with gold nanofibres [Tie Wang, Xiaoge Hu, Shaojun Dong, The Journal of Physical Chemistry B, 2006, 110, 16930].

Despite the possibility of using various substrates, also called soil, the preservation of the surfaces, which offer a strong amplification and reproducibility of the spectrum at every point of the surface, is still problematic. These are extremely important features of the SERS-active surfaces, especially when it comes to the application of this technique in biomedical research or in the development of biosensors [Liu, GL, Lu, Y., Kim, J., Doll, JC, and Lee, LP Adv. 2005 17 2683; Domke, K.F., Zhang, D., and Pettinger, B.J. Am. Chem. Soc. 2007 129 6708; Gunavidjaja, R., Peleshanko, S., Ko, H., and Tsukruk, V.V. Adv. Mater. 2008 20 1544].

Despite the enormous number of literature reports and patent applications, there is currently no method that would ensure the reproducibility of the SERS spectra for a given surface morphology. Surfaces are known for SERS measurements based on nanoparticles, nanowires, nanoprisms. Below are some examples of important applications from this area:

US Patent Application No. US 2008/0 096 005 A1 "Nanostructured Substrate for Surface Enhanced Raman Scattering" relates to the surface of silicon, alumina or titanium dioxide that is coated with gold or silver particles having a size of 20 nm to 140 nm are coated. For one of the exemplary surfaces with adsorbed bacteria E. coli, a gain factor of 2.times.10.sup.4 was achieved, but the aspect of the reproducibility of the surfaces to be produced was not investigated.

The US patent application no. US 2006/0 275 541 A1 "System and method for fabricating substrate surfaces for SERS and apparatuses same same" relates to a substrate for detection of biomolecules with SERS technology, which also controlled and strictly defined vapor deposition the golden or silver thin layers (with PVC method, ie Physical Vapor Deposition) on a surface of glass, liquid crystals or polymers. The authors indicate the amplification factor of the order of 10 <10> for Bacillus subtilis spore adsorbed on one of the exemplary surfaces, but the aspect of reproducibility of the spectrum for one and several different surfaces has not been discussed.

US Pat. No. 7,583,379 B2 "Surface Enhanced Raman Spectroscopy (SERS) systems and methods of use thereof" relates to the SERS substrate for detection of viruses, bacteria and other biosystems, which is based on the or silicon surface arranged, produced by the above-mentioned PVD method silver, nickel or silicon nanowires. Above all, the inventors analyze the dependence between the length, the diameter and the orientation of the nanowires in relation to the surface and the intensity of the recorded SERS spectra, without mentioning the numerical values of the amplification factor, while at the same time assuring that the spectra for a substrate are reproducible are.

The international patent application "Highly efficient enhanced Raman and fluorescence nanostructure substrate" published under No. WO 2009/035479 relates to a SERS substrate based on e.g. a silicon surface coated with the nanowires formed from a core, i. Ga 2 O 3, ZnO, InSb or SiC, from 20 nm to 100 nm long, diameter 40 nm, prepared by VLS method (Vapor-Liquid-Solid Mechanism of Deposition), and a 3 nm to 20 nm thick silver or Gold coating exist. The inventors show that the amplification factor for rhodamine 6G is 35 times higher than on a commercially available Mesophotonics SERS substrate.

The international, published under No. WO2008 / 09/4089 patent application "active sensor surface and a method for manufacture thereof" relates to a SERS substrate, the nanowires or nanotubes from 0.1 .mu.m to 100 .mu.m long, diameter of 5 nm to 400 nm and is coated with silver nanoparticles with a size of 0.5 nm to 100 nm. The inventors merely point to potential application of the substrate in SERS measurements, without having given specific examples.

The method described in the present patent allows a fast, cheap and extremely simple coating of the solid surfaces with golden micro-flowers or golden micro-flowers and golden nanoparticles as well as the control of the coating density and morphology of the golden nanoparticles. The invention allows the preparation of both the mono- and the multilayers of the golden microbloods. The process does not require the use of complex reagents, organic solvents or heavy metals, and specialty equipment. Also no Goldprekursornanopartikel are needed to produce golden microbloods (it is called seedless method). In addition, the method is one-level (one-pot type).

There are patented methods of producing gold surfaces using tetrachloroauric acid and hydroxylamine as reagents.

In the application of the invention no. EP 0 426 300 A1 "Method of producing a reagent containing a narrow distribution of colloidal particles of a selected size and the use thereof", a process for the preparation of large gold nanoparticles has been presented. The first step in this process is to prepare a growth solution that includes gold chloride and hydroxylamine. No reaction is observed in this mixture. Only the second stage - addition of small gold nanoparticles - causes the gold deposition on their surface and results in an increase in their volume.

US Patent No. US 4,005,229 "Novel method for the rapid deposition of gold on a non-metallic substrates at ambient temperatures" refers to the coating of non-metallic surfaces with gold. The coating is carried out by the contact of the surface with an aqueous solution of the gold salts, the complexing agent (surfactant) and hydrazine or hydroxylamine, which are used as a reducing agent. In an improved variant, ions of bivalent heavy metals, mercury, cadmium or lead, or else their mixtures, are also used in the process.

US Pat. No. 6,183,545 "Aqueous solutions for the production of metals by reductive deposition" relates to the preparation of metallic coatings in the presence of dialkylhydroxyl or dialkylaminophosphine. The process involves various metals, including gold, and requires that the reaction mixture contain one of about twenty reducing agents or their salts, including hydroxylamine.

US Pat. No. 6,383,269 B1 "Electroless gold plating solution and process" has disclosed a process for producing gold coatings on the nickel-containing substrates. According to the invention, the surface to be coated is contacted with a mixture, the mixture containing water-soluble gold compounds, electrolyte in the form of the organic salt, and a reducing agent, i.a. Hydroxylamine or its salt may be. The process requires the heating of the mixture at least up to 60 ° C, the temperature range 85-91 ° C is most advantageous. The invention does not provide a way to produce gold coatings on substrates that do not contain nickel.

The authors of the invention application US 2003/3 066 756 A1 "Plating bath and method for depositing a metal layer on a substrate" present an electrolytic process for coating the substrates with gold. The solution used for plating bath contains aqueous solution of hydroxylamine or its derivatives, and the metal surfaces are coated.

The plating bath of similar composition is presented in the invention application US 2003 150 353 A1 "Electroless gold plating solution". This process does not use electrode processes - the gold coating is made by the contact of the substrate with the reaction mixture and results in deposition of at least 15 μg gold per cm 2 of the surface. The objective of the method disclosed in this application is to produce a homogeneous gold coating with the lowest possible porosity. In addition to the source of gold ions and hydroxylamine, the reaction mixture contains complexing, stabilizing reagents, pH buffers and others. The inventors of the invention described in this application unquestionably state (paragraph [0029]) that the presence of the above-mentioned reagents in the solution is the necessary condition for the realization of the invention and the realization of the above-mentioned objective. Moreover, according to the disclosure in the application, the application of the method is limited exclusively to the coating of the metallic surfaces.

The method presented in the present application is that a solid, e.g. a silicon plate, in an aqueous solution containing the source of Au (III) cations, e.g. Tetrachloroauric acid HAuCl 4, as well as its reducing agent - hydroxylamine, e.g. in the form of hydrochloride - is immersed. Subsequently, the plate is rinsed in water and optionally in organic solvent and allowed to dry.

It should be emphasized that none of the inventions presented above requires that only two reagents - tetrachloroauric acid and hydroxylamine hydrochloride - be used for non-electrolytic coating of the surface with gold particles. Moreover, in the mentioned methods, golden micro-flowers, which are characterized by an extremely extensive surface with a comparatively small volume, are not produced.

According to the invention, the process for the coating of hydrophilic solid with a gold layer with extended surface, comprising immersing the surface of the solid in a reaction solution containing gold ions and hydroxylamine, characterized in that the said reaction solution consists of the following components: - Water, The first constituent selected from the group consisting of tetrachloroauric acid HAuCl 4, salts of this acid and mixtures thereof, - Second component selected from the group comprising hydroxylamine, its salts and mixtures thereof.

Preferably, the second component is hydroxylamine hydrochloride NH 2 OH.HCl.

Preferably, the solid is a dielectric solid, semiconductor or metallic solid.

In a preferred embodiment, the molar ratio of the first constituent to the second constituent in the reaction solution is from 1: 8 to 7: 8, more preferably from 1: 8 to 3: 8. To produce golden microblocs with a very extensive surface area, large reductant excesses are used (molar ratio of the first component to the second component is between 1: 8 and 3: 8). Smaller reductant surpluses allow less folded structures to be made.

According to the invention, the concentration of the second component is preferably not less than 0.2 mM, more preferably not less than 0.5 mM, still more preferably not less than 25 mM. In order to produce gold microbubbles with a diameter greater than 1 μm, it is preferable to use the concentrations of the second component greater than 0.5 mM. The golden microblooms are larger for higher concentrations of the reagents.

Preferably, the solution of the first ingredient is added dropwise to the solution of the second ingredient, preferably with constant stirring, whereby the reaction solution is prepared, after which the surface of the solid to be coated is introduced into the reaction solution thus prepared.

At concentrations of the second component above 0.5 mM, it is advantageous to position the surface of the solid to be coated in the reaction solution horizontally.

In one of the preferred embodiments, the surface of the solid to be coated is introduced into the reaction solution for a period not exceeding 10 minutes. This allows the flowers to be made of thin golden leaves ("flakes" with sharp edges instead of rounds).

In another preferred embodiment, the surface of the solid to be coated is introduced into the reaction solution for a period of time longer than 30 minutes. This allows flowers to be made, consisting of golden beads, sticks and plates with round edges.

In yet another preferred embodiment, the surface of the solid to be coated is introduced into the reaction solution for a period longer than 1 hour, more preferably longer than 24 hours. This allows permanent golden coatings to be produced.

In yet another preferred embodiment, to produce a porous, golden material consisting of many layers of golden flowers, the concentration of the second component in the reaction solution is not less than 25 mM, and above the surface of the solid to be coated a column of the reaction solution of the height not less than 1 cm guaranteed.

Preferably, the immersion step of the surface of the solid to be coated is repeated in the reaction solution.

Preferably, the surface of the solid to be coated is not polished. For example, the surface of the solid to be coated is mechanically roughened silicon or frosted glass. The use of non-polished surfaces is advantageous for filling the interstices between the golden microblooms with gold nanoparticles. Surface roughening is also necessary to maintain the mechanical durability of the gold coatings, which are thicker than a microbubble monolayer.

The invention also includes a solid coated with a gold layer having an extended surface area by the method described above.

Should this be applied as a substrate in surface enhanced Raman scattering measurements, SERS, it preferably allows for a gain factor, EF, of not less than 10 <7>, more preferably not less than 10 <8> to reach.

In the process according to the invention, the reaction is preferably conducted at room temperature.

The invention will be explained in more detail below with reference to the preferred embodiments with reference to accompanying drawings. Show it: <Tb> FIG. FIG. 1 shows an SEM image of a single golden nanobeam produced on a silicon surface according to Example 1; FIG. <Tb> FIG. FIG. 2 shows an SEM micrograph of golden nanoblues prepared on a roughened silicon surface according to Example 2; FIG. <Tb> FIG. 3 <SEM> an SEM image of a single golden nanoflower made of thin sheets (flakes) produced on a silicon surface according to Example 3; <Tb> FIG. FIG. 4 shows an SEM image of a silicon surface coated with a monolayer of golden microblooms and gold nanoparticles according to Example 4; FIG. <Tb> FIG. Fig. 5 is a SEM photograph of a porous gold surface coating of a silicon surface consisting of many layers of the gold microbloods prepared according to Example 5; <Tb> FIG. Fig. 6 is a SEM photograph of a microbloom-coated ITO surface prepared according to Example 6; <Tb> FIG. Fig. 7 is a SEM photograph of a microbubble-coated glass surface prepared according to Example 6; <Tb> FIG. Fig. 8 is a SEM photograph of a microblood-coated GaN semiconductor surface prepared according to Example 6; <Tb> FIG. Fig. 9 is a SEM photograph of a microbubble coated surface of the aluminum foil made according to Example 6; <Tb> FIG. 10 <sep> Photographs of the vessels with reaction mixture and recordings of the microblotted layer coated plates. A - Mixture 15 minutes after inserting the plate; B - same mixture after one hour; C - Examples of various substrates coated with nano- and microblooms by the method according to the invention: 1-silicon before coating, 2-type I plate (on silicon), 3-type II plate (on silicon), 4-type I plate (on frosted glass), 5 - Type II plate (on frosted glass); the last image shows a silicon plate (plate # C2) exposed to visible light. As you can see, the plate is covered with a dense layer of metallic gold; <Tb> FIG. Figure 11 shows a Raman microscope (A) used for SERS spectroscopy and its scheme (B); SERS spectra taken from a 10 <-> <6> <Tb> FIG. 12 <M> Solution adsorbed p-Merkaptobenzoesäure, on a surface according to the invention for SERS measurements recorded at various points on the surface (B, C, D, E) and SERS spectra of the substrate itself (A). When recording the spectra, the procedure was as in Example 9, corresponding to, SERS spectra of a 10 <-> <6> <Tb> FIG. 13 <M> Solution adsorbed p-mercaptobenzoic acid on two different surfaces according to the invention for SERS measurements (A and B) taken at different points on each surface. When the spectra were recorded, the procedure was as described in Example 9, SERS spectra being 10 <-> <3> M, 10 <-> <6> M, 10 <-> <9> <Tb> FIG. 14 aqueous solutions adsorbed molecules of L-alanine on surfaces according to the invention for SERS measurements (A, B and C). When the spectra were recorded, the procedure was as in Example 11, and a SERS spectrum from that of a 10 <11> <Tb> FIG. 15 <sep> / ml buffer solution adsorbed QB1 bacteriophage on a surface according to the invention for SERS measurements. When the spectra were recorded, the procedure was as in Example 12.

Materials and reagents

Tetrachloroauric acid and hydroxylamine hydrochloride were purchased from Sigma-Aldrich. Concentrated sulfuric acid and 30% hydrogen peroxide were purchased from Chempur. Roth's matte glass and glass slides, Cemat Silicon polished wafers and ITO (Indium Tin Oxide Plates) were used. The gallium nitride coated sapphire surfaces were purchased from TopGaN. The aluminum surface was prepared by coating a glass plate with commercial aluminum foil.

As solvent for reactions or washing of substrates, distilled water (15 MΩ) and analytically pure acetone and analytically pure methyl alcohol from Chempur were used.

The glass or silicon surfaces were prepared by cutting the material into smaller plates and their multi-stage cleaning for coating with golden microbloods. The first step was washing in water (the plates were placed in a beaker of distilled water and washed in an ultrasonic bath for ten minutes) and then in acetone (same procedure as washing in water). After drying, the surfaces were left in so-called piranha solution (a mixture of 30% hydrogen peroxide and concentrated sulfuric acid in the volume ratio 1: 4) for 15 hours. After the plates were removed from the piranha solution, they were washed three times with water, then rinsed with methanol and allowed to dry.

The ITO surfaces or the gallium nitride coated sapphire surfaces were prepared by washing in water and acetone and then drying.

If a rough surface of silicon, glass or ITO was used in the experiment, then this was roughened with a sandpaper P600, then cut into pieces and washed by the method described above.

The surfaces produced were characterized by scanning electron microscopy (field emission scanning electron microscopy, FE-SEM) using the Auriga microscope from Carl Zeiss.

The images of the reaction mixture and the reaction products are shown in Fig. 10.

Measurement method of the SERS spectra

The SERS spectra were recorded with a high-resolution confocal InVia Raman microspectrometer (Ranishaw). The wavelength of the excitation light was 632.5 nm. The scattered beam was analyzed by means of a diffraction grating in the spectrometer, and the intensities for the individual energies were detected with a highly sensitive CCD detector. The magnification of the laser beam focusing lens on the sample was 50x. The spatial resolution was better than 1 μm, the spectral resolution about 1 cm <-> <1>. The power of the laser used for measurements was from 1 mW to 3 mW for SERS measurements and 150 mW when recording conventional Raman spectra. The spectra were recorded with accumulation times of 10 to 40 seconds. The image (FIG. 11) represents the external view of the microscope (a) and its diagram (b).

Enhancement Factor (EF) describes the ratio of the integrated intensities (intensity at the maxima), the molecules adsorbed on the surface and the molecules in the solution, and is defined by the formula: EF = (ISERS / lRaman) / (NSERS / NRaman); Where: ISERS-measured integrated band intensity in the SERS spectrum of molecules adsorbed on the surface, IRaman - measured integrated band intensity in the Raman spectrum of molecules in solution, NRaman - determines the number of molecules in the solution that were "exposed" to laser light to record the Raman spectrum, NSERS- determines the number of adsorbed molecules that have been "exposed" to laser light to acquire the SERS spectrum.

NRaman was determined by the formula: NRaman = NA * C * Df * πr <2> <> Where: NA Avogadro number, 6.02 · 10 <23>, c - molar concentration of the solution, Depth of focus; Df = 2λ / NA <2>, where for the line 785 nm NA, that is, the aperture of the objective is 0.55, whereby Df = 5 μm πr <2> - geometric cross section of the molecules.

NSERS was estimated on the basis of surface coverage, assuming that the molecules adsorb on the surface by forming a monolayer, and assuming an area of the surface. NSERS = Nm · A Where: Nm - number of molecules in the stock solution used for adsorption; A - the area irradiated by the laser, where A = π · S, where S is the size of the laser spot, which is 50.times.1 .mu.m.sup.2 in the 785 nm line used in the measurements and the objective magnification.

Reproducibility for a substrate - means the reproducibility of the SERS spectra recorded on the substrate at various points on the surface (the correspondence with respect to intensities and positions of the bands in the SERS spectra taken under the same measurement operations ). The parameter was determined as follows: integrals were determined from the area of the difference between two spectra compared, the spectra being recorded on the same substrate but at different points. For reproducible spectra (100% agreement) those were held for which the integrals from the difference area were not different by more than 3%.

Reproducibility for various substrates - means the reproducibility of the SERS spectra recorded on different substrates at different points (the match for intensities and positions of the bands in the SERS spectra taken under the same measurement operations). The parameter was determined as follows: integrals were determined from the area of the difference between two spectra compared, the spectra being recorded on different substrates. For reproducible spectra (100% agreement) those were held for which the integrals from the difference area were not different by more than 3%.

embodiments

Embodiment 1. Preparation of golden microblooms on a silicon surface To the aqueous hydroxylamine solution (2 ml, 8.0 mM) was added dropwise, with vortex mixing, an aqueous solution of tetrachloroauric acid (1.2 ml, 5.0 mM). After intensive mixing (about 10 seconds), a silicon plate was placed in the reaction mixture (previously prepared according to the procedure outlined above). After 24 hours, the plate was taken out of the reaction mixture, rinsed gently in distilled water and methanol, and then left to dry. An SEM micrograph of a single nanorug is shown in FIG.

Exemplary Embodiment 2 Production of Golden Microbubbles and Golden Nanoparticles on a Roughened Silicon Surface The procedure was as in Example 1, but roughened silicon was introduced into the final reaction mixture. A picture of the surface produced with the microblooms is shown in FIG.

Embodiment 3. Preparation of golden microblooms, which consist of gold leaves The procedure was as in Embodiment 1, but the deposition time of the golden microbloods was shortened to ten minutes. An SEM image of a single surface-grown nanoblue is shown in FIG.

Embodiment 4. Preparation of Surfaces Coated with a Monolayer of Golden Microbubbles and Gold Nanoparticles To the aqueous hydroxylamine solution (1 ml, 40.0 mM) was added 1.6 ml of water and then, dropwise, vortex mixing, an aqueous solution of tetrachloroauric acid (0.6 ml, 25.0 mM). After intensive mixing (about 10 seconds), the surface to be coated was introduced into the reaction mixture. After 24 hours, the plate was taken out of the reaction mixture, rinsed gently in distilled water and methanol, and then left to dry. An SEM image of a fragment of the surface coated with a monolayer of golden microbloom and gold nanoparticles is shown in FIG.

Embodiment 5. Preparation of a porous golden material consisting of many layers of golden microbloods To the aqueous hydroxylamine solution (2 ml, 40.0 mM) was added dropwise, with vortex mixing, an aqueous solution of tetrachloroauric acid (1.2 ml, 25.0 mM). After intensive mixing (about 10 seconds), the plate to be coated was introduced into the reaction mixture. After 24 hours, the plate was removed from the reaction mixture, rinsed gently in distilled water and methanol, and allowed to dry. An SEM image of a fragment of the silicon surface coated with an expanded porous surface consisting of many layers of golden microbubbles is shown in FIG.

Also advantageous is immersion of a finished, coated surface in a further reaction mixture. In such variant with some repetitions, the use of so concentrated reagent solutions, as indicated in this embodiment, is not necessary.

Embodiment 6. Preparation of golden microblooms on non-silicon surfaces The procedure was as in Example 1, but non-silicon surfaces were introduced into the final reaction mixtures. They were cleaned sheets of frosted glass, microscopic glass roughened with sandpaper, ITO, sandpapered ITO, the gallium nitride coated sapphire, aluminum. The SEM micrographs of the microblooms prepared on ITO, glass, GaN, and aluminum surfaces are shown, respectively, in Figures 6, 7, 8, and 9.

Exemplary Embodiment 7. Preparation of the Surface for SERS (Type I) The procedure was as in Example 4. The plate prepared by this method was purified of hydroxylamine by the oxygen plasma treatment for 5 minutes. The purified plate was placed in the analyte solution of specified concentration. After removal from the solution, the adsorbent analyte surface was ready for SERS.

Embodiment 8. Preparation of the surface for SERS (Type I) The procedure was as in Example 5. The plate prepared by this method was purified of hydroxylamine by the oxygen plasma treatment for 5 minutes. The purified plate was placed in the analyte solution of specified concentration. After removal from the solution, the adsorbent analyte surface was ready for SERS.

Embodiment 9. SERS spectra of p-Merkaptobenzoesäure Type I SERS surface was immersed in the 10 <-6> M p-mercaptobenzoic acid solution. Subsequently, the substrate was dried and recorded 30 Ramanspektren at various points of the surface. Figure 12 illustrates four randomly selected spectra of the p-mercaptobenzoic acid adsorbed on the SERS surface (B, C, D, E) and the spectrum of the substrate itself (A). The spectra became within 10 seconds using the excitation line 632.5 nm with 2.5 mW power, recorded.

In a preferred example, the spectra recorded at different points on the substrate are identical. The spectra contain strong bands at frequencies: 1080 and 1590 cm <-> <1>, whose relative intensities are practically the same in each of the recorded spectra.

In further experiments, the reproducibility of the SERS spectra to be recorded was checked for various substrates produced by the same method. The spectra of the p-mercaptobenzoic acid adsorbed on 10 further Type I surfaces were recorded. FIG. 13 presents the results for two randomly selected substrates A i B produced by methods according to the invention.

In addition, the amplification factor EF for the adsorbed on a SERS surface p-Merkaptobenzoesäure was estimated by the following formula: EF = (ISERS / lRaman) / (NSERS / NRaman) Where: ISERS and IRaman are measured integrated band intensities in the spectra of the molecules of the p-mercaptobenzoic acid (ISERS) adsorbed on a SERS surface and the molecules of p-mercaptobenzoic acid in a 10 <-> M solution (IRaman); NSERSand NRaman determine the number of adsorbed molecules of p-mercaptobenzoic acid that were "exposed" to laser light to record the SERS and Raman spectra accordingly.

ISERS and lRaman were measured for the 1180 cm <-> <1> band. NSERS was estimated from the surface coverage of p-mercaptobenzoic acid (1 x 10 <14> molecules / cm 2) [B. Pettinger, B. Ren, G. Picardi, R. Schuster, G. Ertl, J. Raman Spectrosc. Volume 36 Issue 6-7, Pages 541-550]. NRaman, on the other hand, refers to the number of molecules of p-mercaptobenzoic acid in the solution to be investigated, calculated according to the definitions given above.

In a preferred embodiment of the inventive SERS surface, the estimated gain factor (EF) for the p-mercaptobenzoic acid was 1.2 x 10 8 and was four orders of magnitude higher than that estimated for a commercially available SERS substrate ,

Preferably, the frequencies and relative band intensities of p-Merkaptobenzoesäure for four different surfaces produced with the same inventive method reproducible. The reproducibility of the frequencies and relative band intensities is higher than 70% for four substrates B, C, D and E produced according to the invention (FIG. 12).

Embodiment 10. SERS spectra of p-Merkaptobenzoesäure In another preferred embodiment, the reproducibility of the recorded spectra for the same surface and for two different surfaces was checked. The wavelength of the excitation radiation used in measurements was 632.5 nm, the laser power at the sample was 3 mW, and the accumulation time was about 10 s.

Preferably, the spectra of the molecules of the p-mercaptobenzoic acid adsorbed on the SERS surface from their aqueous 10 × 6 M solution, recorded at different points on the surface, are reproducible. The relative intensities of the bands characteristic of p-mercaptobenzoic acid at the frequencies 840, 1080 and 1589 cm <-> <1> are 70% reproducible for all recorded spectra.

Embodiment 11. SERS spectra of L-alanine In a further preferred embodiment, the sensitivity of the fabricated SERS surfaces was checked. On the Type I surface, molecules of L-alanine were adsorbed from the solutions with concentrations of 10 <-3> M, 10 <-> 6> M and 10 <-> 9> M (Figure 14). The wavelength of the excitation radiation used in measurements was 632.5 nm, the laser power at the sample was 3 mW, and the accumulation time was about 10 s.

Preferably, for SERS measurements, the surface gives a high enhancement to the SERS spectrum of the molecules of L-alanine adsorbed from their aqueous, even 10 X 9 M solution.

Embodiment 12. SERS spectra of bacteriophages In another preferred embodiment, 2 microliters of QBeta bacteriophages from a 10 <11> / ml solution were applied to a Type II SERS substrate, and after drying the surface, the SERS spectra were recorded (Figure 15). When recording the spectra, the excitation wavelength 632.5 nm was used, the laser power at the sample was 10 mW, and the accumulation time was about 10 s. The results obtained indicate that the SERS surface produced according to the invention can be used in biological and medical examinations.

Claims (10)

A process for coating hydrophilic solids with a gold layer, comprising immersing the surface of the solid in a reaction solution containing gold ions and hydroxylamine, characterized in that the reaction solution consists of the following constituents: - Water, The first constituent selected from the group consisting of tetrachloroauric acid HAuCl 4, salts of this acid and mixtures thereof, - Second component selected from the group comprising hydroxylamine, its salts and mixtures thereof. 2. The method according to claim 1, characterized in that the second constituent Hydroxylaminyhydrochlorid NH2OH · HCl. 3. The method according to any one of the preceding claims, characterized in that the solid body is a dielectric solid, semiconductor or metallic solid. 4. The method according to any one of the preceding claims, characterized in that the molar ratio of the first constituent to the second constituent in the reaction solution of 1: 8 to 7: 8, preferably from 1: 8 to 3: 8, is. A method according to any one of the preceding claims, characterized in that the concentration of the second constituent in the reaction solution is not less than 0.2 mM, preferably not less than 0.5 mM, still more preferably not less than 25 mM. 6. The method according to any one of the preceding claims, characterized in that a solution of the first constituent is added dropwise to a solution of the second constituent, preferably with constant stirring, whereby the reaction solution is prepared, after which the surface of the solid to be coated in the thus prepared Reaction solution is introduced. 7. The method according to any one of the preceding claims, characterized in that the concentration of the second constituent in the reaction solution is greater than 0.5 mM and that the surface of the solid to be coated in the reaction solution is positioned horizontally. 8. The method according to any one of the preceding claims, characterized in that the surface of the solid to be coated is introduced into the reaction solution for a period of time which is not longer than 10 minutes. 9. The method according to any one of the preceding claims 1 to 7, characterized in that the surface of the solid to be coated is introduced into the reaction solution for a period of time which is longer than 30 minutes. 10. The method according to any one of claims 1 to 7, 9, characterized in that the surface of the solid to be coated is introduced into the reaction solution for a period of time longer than 1 hour, preferably longer than 24 hours.