Deposition Of Au Nanoparticles Research Articles

Led-induced deposition of Pt and Au NPs on carbon fibers: Developing a novel strategy for facile fabrication of electrocatalysts for enhanced methanol electrooxidation

In addressing the imperative of aligning materials science with sustainable development, our study introduces an innovative method for the simultaneous deposition of Pt and Au nanoparticles onto a carbon support. This research represents the pioneering application of the photodeposition process for synthesizing bimetallic nanoparticles on a carbon matrix. The comprehensive characterization of the resulting nanostructures involves various techniques, including field X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM), atomic force microscopy (AFM), energy-dispersive X-ray analysis (EDX), inductively coupled plasma atomic emission spectroscopy (ICP-OES), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetric techniques. Our findings reveal that the photodeposition method produces a homogeneous AuPt nanostructure, demonstrating superior electrocatalytic activity in methanol oxidation compared to the monometallic carbon fiber_Pt (CF_Pt) catalyst. These results emphasize the effectiveness of our novel approach in fabricating electrocatalysts with exceptional performance in methanol oxidation reactions.

Preparation of novel Au-Nb3O7F nanosheets for the photodegradation of tetracycline hydrochloride.

Water pollution caused by antibiotics is a growing problem and photodegradation by efficient catalysts is an environmentally friendly technology that can effectively degrade organic pollutants in water. Here, a novel method was innovatively used to synthesize niobium oxyfluoride (Nb3O7F) nanosheets decorated with Au nanoparticles, which is the first report for the composites of Au and Nb3O7F. We prepared the Nb3O7F nanosheets via hydrothermal synthesis followed by deposition of Au nanoparticles on their surface using HAuCl4. The prepared samples were characterized by XRD, HRTEM, XPS, and UV-Vis. The diameters of most Au NPs are ranging from 5 to 25nm with an average size of about 16.9nm, as well as the Nb3O7F nanosheets in size ranging from 200nm to 700nm. The chemical composition of the Au-Nb3O7F showed a Au/Nb atomic ratio of 1/10, as well as a Nb/O/F ratio of 3/7/1. UV-Vis spectrum reveals a largest absorption peak at 520nm for the Au-Nb3O7F nanosheets. The prepared Au-Nb3O7F nanomaterials were applied to the visible-light photodegradation of tetracycline hydrochloride, with the photocatalytic degradation rate reached more than 50% under the optimal conditions within 1h. Capture experiments indicated that h+ and •O2 - are the main active substances involved during the course of the photodegradation. Furthermore, the proposed mechanism for the photodegradation of the novel Au-Nb3O7F nanosheets was given.

Scalable Superhydrophilic Solar Evaporators for Long-Term Stable Desalination, Fresh Water Collection and Salt Collection by Vertical Salt Deposition.

Solar-driven interfacial evaporation (SIE) is very promising to solve the issue of fresh water shortage, however, poor salt resistance severely hinders long-term stable SIE and fresh water collection. Here, we report design of superhydrophilic solar evaporators for long-term stable desalination, fresh water collection and salt collection by vertical salt deposition. The evaporators are prepared by sequentially deposition of silicone nanofilaments, polypyrrole and Au nanoparticles on a polyester fabric composed of microfibers. The evaporators feature excellent photothermal effect and ultrafast water transport, due to their unique micro-/nanostructure and superhydrophilicity. As a result, during SIE the salt gradually deposits vertically rather than occupies larger area on the evaporators. Consequently, long-term stable SIE with high evaporation rates of 2.4-2.1 kg m-2 h-1 for 3.5-20 wt % brine in continuous 10 h is achieved under 1 sun illumination. Meanwhile, the loosely deposited salt can be easily collected, realizing zero brine discharge. Moreover, scalable preparation of the evaporator is achieved, which exhibits efficient collection of high quality fresh water (10.08 kg m-2 in 8 h) via SIE desalination under weak natural sunlight (0.46~0.66 sun). This strategy sheds a new light on the design of high-performance solar evaporators and their real-world fresh water collection.

Ultrasound-Driven Deposition of Au and Ag Nanoparticles on Citrus Pectin: Preparation and Characterisation of Antimicrobial Composites.

Pectin is a renewable, non-toxic and biodegradable polymer made of galacturonic acid units. Its polar groups make it suitable for complexing and supporting metallic nanoparticles (NPs). This work aimed to produce antibacterial nanocomposites using pectin and acoustic cavitation. The metal NPs (Au or Ag) were deposited using ultrasound (US, 21 kHz, 50 W) and compared with those achieved with mechanical stirring. The impact of the reducing agents (NaBH4, ascorbic acid) on the dispersion and morphology of the resulting NPs was also assessed. Characterization by diffuse reflectance (DR) UV-Vis-NIR spectroscopy and field emission scanning electron microscopy (FESEM) showed that the use of US improves the dispersion and decreases the size of both Au and Ag NPs. Moreover, with Au NPs, avoiding external reductants led to smaller NPs and more uniform in size. The prepared NPs were functionalized with oxytetracycline in water and tested against Escherichia coli (gram negative) and Staphylococcus epidermidis (gram positive) via the Kirby-Bauer test. The results show a better antibacterial activity of the functionalized nanoparticles compared to antibiotic-free NPs and pure oxytetracycline, advising the potential of the nanoparticles as drug carriers. These findings underscore the significance of US-assisted synthesis, paving the way to new environmentally friendly antimicrobial materials.

High‐Resolution Patterning of Conductive Microstructures by Electrostatic Deposition of Aerosol Au Nanoparticles through the Dielectric Mask

A new approach of electrostatically focusing nanoparticles through an electrical tape mask to form narrow <10 μm and conductive microstructures is developed and investigated in this work. The presented approach is similar to deposition of material through a stencil and allows one to obtain lines 15 times smaller than the width of the gap in the mask. It is proposed to use ordinary polyvinyl chloride (PVC) electrical tape as a mask instead of expensive photo or electronic resists. The work investigates the influence of a mask thickness (height) of 60–180 μm, a gap width of 120–380 μm, a substrate potential of 0.1–5 kV, and a deposition time of 10 and 120 min on the geometry and electrical properties of the lines. Charged Au nanoparticles 60 nm in size synthesized by spark discharge are the building blocks of microstructures. Numerical modeling of the process of focusing nanoparticles in COMSOL qualitatively confirms the found experimental dependencies. The electrical resistivity of the sintered lines is 6.34 times higher than that of bulk gold. The developed approach makes it possible to obtain high‐aspect microstructures and supports operation at atmospheric pressure.

Gyroid‐Structured Au Materials with 3D Interconnected Networks for Highly Efficient Heat Localization and Solar Vapor Generation

Effective solar steam generation is regarded as a prospective technology for seawater desalination and water purification, owing to its capability of solar light absorption and heat conversion. Numerous efforts have been dedicated to exploring photothermal materials with various delicate microstructures. However, investigations of the coupling effect of structure and component still need to be done. Herein, a superior solar steam generator of 3D bicontinuous interconnected gyroid‐structured Au materials (Au gyroid) by depositing Au nanoparticles onto C. rubi butterfly wings is reported. Au gyroid is proven to possess the evaporation rate and efficiency of 1.29 kg m−2 h−1 and 74.0%, under 1 sun irradiation. What is more, the evaporation rate and efficiency of lattice‐structured Au materials (Au lattice) as a comparison are 1.14 kg m−2 h−1 and 65.4%. The outstanding performance of Au gyroid is mainly ascribed to its 3D densely distributed hotspots and interconnected nanochannels, which are beneficial for strong broadband light absorption, sufficient water supply, as well as confinement effect for water heating. This work will provide insight into the future design and synthesis of novel plasmonic absorbers in photothermal conversion, photocatalysis, and photovoltaic devices.

Investigation of biosensing properties in magnetron sputtered metallized UV-curable polymer microneedle electrodes

Direct management and assessment of metal film properties applied to polymer microneedle (MN) biosensors remains difficult due to constraints inherent to their morphology. By simplifying the three-dimensional structure of MNs and adjusting the deposition time, different thicknesses of Au films were deposited on the UV-cured polymer planar and MN substrates. Several properties relevant to the biosensing of the Au films grown on the polymer surfaces were investigated. The results demonstrate the successful deposition of pure and stable Au nanoparticles onto the surface of UV-curable polymer materials. Initially, Au islands formed within the first minute of deposition; however, as the sputtering time extended, these islands transformed into Au nanoparticle films and disappeared. The hydrophilicity of the surface remains unchanged, while the surface resistance of the thin film decreases with increasing thickness, and the adhesion to the substrate decreases as the thickness increases. In short, a sputtering time of 5–6 min results in Au films with a thickness of 100–200 nm, which exhibit exceptional comprehensive biosensing performance. Additionally, MNs made of Au/UV-curable polymers and produced using magnetron sputtering maintain their original shape, enhance their mechanical characteristics, and gain new functionalities. The Au/UV-curable polymer MNs exhibited remarkable electrode performance despite being soaked in a 37 °C PBS solution for 14 days. These discoveries have important implications in terms of decreasing the dependence on valuable metals in MN biosensors, lowering production expenses, and providing guidance for the choice and design of materials for UV-curable polymer MN metallization films.

Mining wastes as CO oxidation mesoporous catalysts from the Fe-skarns of Serifos Island, Cyclades, Greece

The Fe-skarns from the Greek Island of Serifos in Cyclades has been utilized only for the exploitation of magnetite ores, while significantly vast amounts of red and yellow hematite ores remained unexploited as mining wastes. This study explores the effective utilization of such mining wastes per se, as active mesoporous catalysts for energy applications, taking CO oxidation as a model reaction. The results of our multi-analytical study have illustrated that the physicochemical characteristics of the hematite materials can be positively influenced by the implementation of a simple calcination step, while the characteristics of magnetite remained unaffected. The calcined yellow and red mineral hematite from Serifos Fe-skarns mining wastes per se, act beneficial in the catalytic activity with respect to calcined magnetite catalyst. The calcinated counterparts of hematite, and especially yellow hematite, can efficiently be used as a support for depositing Au nanoparticles, and thus achieving even higher activity for CO oxidation (90% CO conversion), at much lower temperatures (T ∼62.0 °C). The mining wastes per se of Serifos, mainly of mesoporous hematite, are particularly active for CO oxidation, without any complex pretreatments or activation or functionalization in the context of circular economy.

Au nanoparticles decorated β-Bi2O3 as highly-sensitive SERS substrate for detection of methylene blue and methyl orange.

In this work, Au/Bi2O3 was synthesized by loading Au nanoparticles (NPs) onto β-Bi2O3 by a simple solution reduction method. β-Bi2O3 was synthesized by a precipitation-thermal decomposition procedure, which results in significantly improved SERS detection limits down to 10-9 M for methylene blue (MB) and 10-7 M for methyl orange (MO) as probe molecules, comparable to those reported for the best semiconductor SERS substrates. In particular, further deposition of Au NPs (5.20% wt%) onto β-Bi2O3 results in a two-order-of-magnitude enhancement in detection sensitivity, achieving a detection limit of 10-11 M for MB and 10-9 M for MO. Under ultraviolet/visible irradiation, the Au/Bi2O3 hybrids substrate exhibits superior self-cleaning ability due to its photocatalytic degradation ability which can be applied repeatedly to the detection of pollutants. The advanced composite substrate simultaneously achieved ultra-low mass loading of Au NPs, outstanding detection performance, good reproducibility, high stability and self-cleaning ability. The development strategy of low load noble metal coupled high performance semiconductor β-Bi2O3 to obtain nano-hybrid materials provides a method to balance SERS sensitivity, cost effectiveness and operational stability, and can be synthesized in large quantities, which is a key step towards commercialization and has good reliability prospects.

Plasmon mediated SERS and photocatalysis enhancement in Au nanoparticle decorated 2D-TiSe2

The combination of 2D materials and noble metallic nanostructure is becoming an attractive research domain for label-free, highly sensitive surface-enhanced Raman spectroscopy (SERS) applications. This study demonstrated photocatalysis degradation and SERS enhancements of organic fluorophore (Rhodamine 6G) on two-dimensional (2D) TiSe2 using Raman spectroscopy. The Au nanoparticles (NPs) were decorated on TiSe2 thin films by thermal annealing at variable temperatures. The selective deposition of Au NPs on the hexagonal TiSe2 nanocrystals increases surface roughness, creating a larger surface area for molecule adsorption. It has been observed that the Au decoration at 250 °C on TiSe2 exhibits efficient detection capabilities for R6G with the Raman intensity enhancement factors of the order of ≈105 along with the significantly improved visible light-induced photodegradation efficiency. The optimized Au NP size creates large electromagnetic hot spots produced by strong plasmon coupling that assists in the charge transfer mechanism among TiSe2, Au NPs, and R6G for enhanced SERS and photocatalysis activities. It has been observed that the intensity of Raman scattering decreases as the Au NP size increases on the TiSe2 material. A possible charge transfer mechanism is proposed with an energy band diagram. The simultaneous measurement of SERS and photocatalytic dye degradation in Au decorated TiSe2 can be used as a sensitive technique for water pollution treatment and biodegradable organic contaminants for the environmental ecosystem.

Enhanced on-Chip modification and intracellular hydrogen peroxide detection via gigahertz acoustic streaming microfluidic platform

Developing effective strategies for the flexible control of fluid is vital for microfluidic electrochemical biosensing. In this study, a gigahertz (GHz) acoustic streaming (AS) based sonoelectrochemical system was developed to realize an on-chip surface modification and sensitive hydrogen peroxide (H2O2) detection from living cells. The flexible and controlled fluid surrounding the electrochemical chip was optimized theoretically and applied in the sonoelectrochemical deposition of Au nanoparticles (AuNPs) first. Under the steady and fast flow stimulus of AS, AuNPs could be synthesized with a smaller and evener size distribution than the normal condition, allowing AuNPs to show an excellent peroxidase-like activity. Moreover, the AS also accelerated the mass transport of target molecules and improved the catalytic rate, leading to the enhancement of H2O2 detection, with an extremely low detection limit of 32 nM and a high sensitivity of 4.34 μA/ (mM·mm2). Finally, this system was successfully applied in tracking H2O2 release from different cell lines to distinguish the cancer cells from normal cells. This study innovatively integrated the surface modification and molecules detection process on a chip, and also proposed a simple but sensitive platform for microfluidic biosensing application.

Tuning CH4 Productivity from Visible Light‐Driven Gas‐Phase CO2 Photocatalytic Reduction on Doped g‐C3N4/TiO2 Heterojunctions

Herein, visible light‐driven gas‐phase photocatalytic CO2 reduction into CH4 is tuned by designing optimized three‐component Au/doped C3N4/TiO2 composite photocatalysts. The key point strategy consists in the formation of high‐quality C3N4/TiO2 heterojunction by associating low containing doped graphitic carbon nitride to commercially available TiO2 UV‐100. Those heterojunctions result in both visible light sensitization and increased charge‐carrier separation. Further deposition of small Au nanoparticles (≈3 nm), quite exclusively onto TiO2 surfaces, mainly acts as electron trapping/cocatalytic functions without excluding surface plasmonic effects. The resulting doped g‐C3N4 material exhibits enhanced visible light harvesting properties, especially in the case of C‐doping. In addition, it is assumed that B– and C–C3N4 doping, leading to a more or less lower conduction band position, is the impacting factor toward total CH4 selectivity achievement. The (0.77 wt%)Au/(0.59 wt%)C–C3N4/TiO2 composite photocatalyst, exhibiting the best compromise between the various impacting factors, leads to a continuous productivity rate of CH4 of 8.5 μmol h−1 g−1 under visible light irradiation over at least 10 h. To the best of knowledge, this level of performance is unprecedented under continuous gas‐phase flowing CO2 in the presence of water as reducing agent, without addition of any sacrificial agent.

Biomimetic dual-nanozymes with catalytic cascade reactions against diabetic wound infection

Diabetes-related chronic wounds characterized by hyperglycemia and weak alkaline milieu provide numerous advantages for bacteria growth and biofilm formation, setting a myriad of stumbling blocks for wound healing. Therefore, reshaping the spatially and temporally pathological wound microenvironment against bacterial infection is critical to rescue stalled healing progress in diabetes-related chronic wounds. Herein, we demonstrate on the room-temperature construction of a glucose oxidase (GOx)-mimicking and peroxidase (POD)-mimicking dual-nanozymes catalytic cascade system upon the partial reduction of Fe3+ to Fe2+ and the deposition of Au nanoparticles, simultaneously. The as-prepared dual-nanozymes catalytic cascade system possesses the capabilities of reshaping the pathological microenvironments of diabetic wound via glucose consumption and acidification, leading to amplified catalytic cascade activities for sterilization. On the one hand, the GOx-mimicking enzymatic activity of the catalytic cascade system can not only deplete glucose and acidize wound milieu to inhibit bacteria growth, but also utilize the weak alkaline milieu of diabetic wound to provide sufficient H2O2 and a favorable pH for subsequent OH generation. On the other hand, the POD-mimicking enzymatic activity of the catalytic cascade system can continuously produce OH for sterilization under the weak acidic milieu in the presence of abundant H2O2. Benefiting from the simply and mild preparation process and the excellent dual-nanozymes catalytic cascade activities under the deliberate evolved milieus of diabetes-related chronic wounds, our catalytic cascade system exhibits the promising healing effect and clinical translation potential against diabetic wound infection.

An ultrasound-activated heterojunction as ROS generator given scaffolds sonodynamic antibacterial effect

Potassium niobate (KNbO3) with favorable biocompatibility presented a great potential in the sonodynamic therapy of implant-related infection due to its superior piezoelectric performance. However, the rapid electron-hole pair recombination weakened its sonodynamic therapy effect. In this work, Au@KNbO3 heterojunctions were synthesized by depositing Au nanoparticles on KNbO3, and then mixed with poly-l-lactic acid (PLLA) powder to prepare scaffold by laser additive manufacturing. Herein, Au with lower Fermi level acted as electron trap to capture the ultrasonic-excited electrons from KNbO3. Subsequently, Au formed Schottky barrier with KNbO3 to prevent electrons backflow. As a result, the electron-hole was expected to be separated. EIS curves indicated that Au@KNbO3 presented a smaller arc radius than that of KNbO3, confirming the electron-hole separation efficiency of Au@KNbO3 was enhanced. Following that, ROS generation ability of the scaffold was significantly strengthened. Antibacterial tests revealed that the generated ROS could not only trigger protein leakage by disrupting bacterial cell membranes, but also deplete glutathione to weaken the antioxidant defense of bacteria. As a consequence, the scaffold exhibited excellent antibacterial abilities of 92% and 90% against S. aureus and E. coli, respectively. Collectively, this work provided a promising countermeasure to fight the implant-related infection.

Single-step fabrication of hybrid germanium-gold/silver nanoentities by femtosecond laser ablation and applications in SERS-based sensing

We present a simple, fast, and single-step approach for fabricating hybrid semiconductor-metal nanoentities through liquid-assisted ultrafast (∼50 fs, 1 kHz, 800 nm) laser ablation. Femtosecond (fs) ablation of Germanium (Ge) substrate was executed in (i) distilled water (ii) silver nitrate (AgNO3—3, 5, 10 mM) (iii) Chloroauric acid (HAuCl4—3, 5, 10 mM), yielding the formation of pure Ge, hybrid Ge-silver (Ag), Ge-gold (Au) nanostructures (NSs) and nanoparticles (NPs). The morphological features and corresponding elemental compositions of Ge, Ge-Ag, and Ge-Au NSs/NPs have been conscientiously studied using different characterization techniques. Most importantly, the deposition of Ag/Au NPs on the Ge substrate and their size variation were thoroughly investigated by changing the precursor concentration. By increasing the precursor concentration (from 3 mM to 10 mM), the deposited Au NPs and Ag NPs’ size on the Ge nanostructured surface was increased from ∼46 nm to ∼100 nm and from ∼43 nm to ∼70 nm, respectively. Subsequently, the as-fabricated hybrid (Ge-Au/Ge-Ag) NSs were effectively utilized to detect diverse hazardous molecules (e.g. picric acid and thiram) via the technique of surface-enhanced Raman scattering (SERS). Our findings revealed that the hybrid SERS substrates achieved at 5 mM precursor concentration of Ag (denoted as Ge-5Ag) and Au (denoted as Ge-5Au) had demonstrated superior sensitivity with the enhancement factors of ∼2.5 × 104, 1.38 × 104 (for PA), and ∼9.7 × 105 and 9.2 × 104 (for thiram), respectively. Interestingly, the Ge-5Ag substrate has exhibited ∼10.5 times higher SERS signals than the Ge-5Au substrate.

Enhanced Photocatalytic CO2 Reduction to CH4 Using Novel Ternary Photocatalyst RGO/Au-TNTAs

Photocatalytic CO2 reduction into hydrocarbon fuels is one of the most efficient processes since it serves as a renewable energy source while also lowering atmospheric CO2 levels. The development of appropriate materials and technology to attain greater yield in CO2 photoreduction is one of the key issues facing the 21st century. This study successfully fabricated novel ternary reduced graphene oxide (RGO)/Au-TiO2 nanotube arrays (TNTAs) photocatalysts to promote CO2 photoreduction to CH4. Visible light-responsive RGO/Au-TNTAs composite was synthesized by facile electrochemical deposition of Au nanoparticles (NPs) and immersion of RGO nanosheets onto TNTAs. The synthesized composite has been thoroughly investigated by FESEM, HR-TEM, XRD, XPS, FT-IR, UV-Vis DRS, and PL analyzer to explain structural and functional performance. Under the source of visible light, the maximum yield of CH4 was attained at 35.13 ppm/cm2 for the RGO/Au-TNTAs composite photocatalyst after 4 h, which was considerably higher by a wide margin than that of pure TNTAs, Au-TNTAs and RGO-TNTAs. The CO2 photoreduction of the RGO/Au-TNTAs composite has been improved due to the combined effects of Au NPs and RGO. Due to its surface plasmonic resonance (SPR) mechanism, Au NPs play a crucial role in the absorption of visible light. Additionally, the middle RGO layers serve as effective electron transporters, facilitating better separation of electron-hole pairs. The newly constructed composite would be a promising photocatalyst for future photocatalytic applications in other fields.

Deposition of Au Nanoparticles onto Poly(3,4-ethylenedioxy - thiophene) Functionalized Multi-Walled Carbon Nanotubes for Label-Free Immunosensing

Deposition of Au Nanoparticles onto Poly(3,4-ethylenedioxy - thiophene) Functionalized Multi-Walled Carbon Nanotubes for Label-Free Immunosensing

Creation of Nanotips on ITO Electrode by Nanoparticle Deposition: An Easy Way to Enhance the Performance of Electrically Responsive Photonic Crystal and Fabricate Electrically Triggered Anticounterfeiting Tags

AbstractElectrically responsive photonic crystals (ERPC) are promising materials for electrophoretic displays, smart windows, and tunable optical devices. However, the high working voltage limits the application of most polar ERPCs because it damages color saturation, response stability, and reversibility. Herein, an easy but general method based on the modification of electrodes with nanoparticles is developed to improve ERPC's performance. The deposition of Au, Cu, or Cu2O nanoparticles created nanotip structures on the electrode, which enhanced the charge injection and local electric field strength, lowered 43% of the working voltage, and increased the color saturation. Meanwhile, the lowered voltage inhibited the electrodeposition of colloidal particles and the electrochemical reaction, which also improved the stability and reversibility of the electrical response. Based on the region‐selective modification of the electrode and the resulting asymmetric electrical response, an electrically triggered tag with a “pattern showing/hiding” effect is fabricated for anticounterfeiting purposes.

Gold-decorated laser-induced graphene for wearable biosensing and joule heating applications

BackgroundLaser-induced graphene from polyimide (PI) substrate has attracted much attention due to its controllable morphology and patternable structure. However, the property of polyimide-derived graphene (PDG) should be further improved to meet the requirement of next-generation flexible devices. MethodsIn this article, Au-modified PDG has been fabricated via the CO2 laser scribing on the common PI substrate. The obtained PDG with a foam-like morphology can provide large accessible sites for the deposition of Au nanoparticles (ANPs) by thermal evaporation. Significant findingsThe ANP-PDG devices have been utilized as electrochemical and surface-enhanced Raman scattering (SERS) sensors for the detection of dopamine (DA), Rhodamine 6G (R6G), and Adenine (Ad), respectively. The properties of the electrothermal heater based on the ANP-PDG films are also investigated. Due to the high conductivity and unique plasmonic effect of ANPs, the ANP-PDG displays higher electrocatalytic activity and stronger SERS signals than that of bare PDG film. The ANP-PDG also can reach higher steady-state temperatures (Ts) compared to the bare PDG heater. Furthermore, the ANP-PDG devices precisely defined on the PI substrate reveal great mechanical flexibility and the sheet resistance is very stable without obvious change, which can be applied for next-generation flexible electronics.

Magnetic polyphosphazene@Au particles as substrates for multiple-detection of immunoproteins by surface-enhanced Raman spectroscopy

Au coated magnetic polyphosphazene (MPCTP) composite particles (MPCTP@Au) were fabricated with sensitive SERS activity. The MPCTP particles were generated by coating polyphosphazene on Fe3O4 nanoparticles through precipitation polycondensation of hexachlorocyclotriphosphazene and phloroglucinol. MPCTP@Au composite particles were obtained by deposition of Au nanoparticles on MPCTP by the reduction of HAuCl4. The size and the thickness of the Au shell can be controlled by varying the amount of HAuCl4. The magnetic core endowed the composite particles with good magnetic responsiveness, which allowed the analyte to be enriched and separated from the complex matrix, and significantly simplifying the sample pretreatment procedure. The SERS activity of MPCTP@Au composite particles were evaluated by DTNB as model Raman reporter, and the limits of detection (LOD) of DTNB was 10-8 mol/L. A high efficient SERS immunoassay system based on the MPCTP@Au substrates for the detection of immunoproteins was developed. Human IgG and rabbit IgG were quantitatively determinated simultaneously by this immunoassay system. The quantitative determination of the immunoglobulin G (IgG) was achieved and the LOD of human IgG, rabbit IgG and the mixture of human IgG and rabbit IgG were as low as 10 fg/mL, 100 pg/mL and 1 ng/mL, respectively. The results showed that the MPCTP@Au composite particles have broad application prospects as high performance SERS active substrates for immunoprotein analysis.