Porous Gold Nanoparticles Research Articles

Nanoporous Submicron Gold Particles Enable Nanoparticle-Based Localization Optoacoustic Tomography (nanoLOT).

Localization optoacoustic tomography (LOT) has recently emerged as a transformative super-resolution technique breaking through the acoustic diffraction limit in deep-tissue optoacoustic (OA) imaging via individual localization and tracking of particles in the bloodstream. However, strong light absorption in red blood cells has previously restricted per-particle OA detection to relatively large microparticles, ≈5µm in diameter. Herein, it is demonstrated that submicron-sized porous gold nanoparticles, ≈600nm in diameter, can be individually detected for noninvasive super-resolution imaging with LOT. Ultra-high-speed bright-field microscopy revealed that these nanoparticles generate microscopic plasmonic vapor bubbles, significantly enhancing opto-acoustic energy conversion through a nano-to-micro size transformation. Comprehensive in vitro and in vivo tests further demonstrated the biocompatibility and biosafety of the particles. By reducing the detectable particle size by an order of magnitude, nanoLOT enables microangiographic imaging with a significantly reduced risk of embolisms from particle aggregation and opens new avenues to visualize how nanoparticles reach vascular and potentially extravascular targets. The performance of nanoLOT for non-invasive imaging of microvascular networks in the murine brain anticipates new insights into neurovascular coupling mechanisms and longitudinal microcirculatory changes associated with neurodegenerative diseases.

Sponge-shaped Au nanoparticles: a stand-alone metallic photocatalyst for driving the light-induced CO2 reduction reaction

Coinage metal nanoparticles (NPs) enable plasmonic catalysis by generating hot carriers that drive chemical reactions. Making NPs porous enhances the adsorption of reactant molecules. We present a dewetting and dealloying strategy to fabricate porous gold nanoparticles (Au-Sponge) and compare their CO2 photoreduction activity with respect to the conventional gold nanoisland (Au-Island) morphology. Porous gold nanoparticles exhibit an unusually broad and red-shifted plasmon resonance which is in agreement with the results of finite difference time domain (FDTD) simulations. The key insight of this work is that the multi-step reduction of CO2 driven by short-lived hot carriers generated by the d → s interband transition proceeds extremely quickly as evidenced by the generation of methane. A 3.8-fold enhancement in the photocatalytic performance is observed for the Au-Sponge in comparison to the Au-Island. Electrochemical cyclic voltammetry measurements confirm the 2.5-fold increase in the surface area and roughness factor of the Au-Sponge sample due to its porous nature. Our results indicate that the product yield is limited by the amount of surface adsorbates i.e. reactant-limited. Isotope-labeled mass spectrometry using 13CO2 was used to confirm that the reaction product (13CH4) originated from CO2 photoreduction. We present the plasmon-mediated photocatalytic transformation of 4-aminothiophenol (PATP) into p,p'-dimercaptoazobenzene (DMAB) using Au-Sponge and Au-Island samples.

Self-enhanced nanohydrogel electrochemiluminescence biosensor based on CRISPR/Cas12a and gold platinum nanoparticles modification for high-sensitivity detection of Burkholderia pseudomallei

The simple, rapid, and accurate detection of highly lethal melioidosis is crucial for early clinical diagnosis and improving cure rates. Currently, due to time consumption, low sensitivity and detection rate the existing clinical detection methods cannot satisfy the needs of clinical diagnosis. Herein, a novel self-enhanced porous hydrogel material (Au@PEI-ABEI@Pt) for ultrasensitive ECL strategy of detection B. pseudomallei was report. The novel porous hydrogel material composed of PEI-ABEI porous hydrogel, gold nanoparticles (AuNP) and platinum nanoparticles (PtNP) have large specific surface area and porous structure, which not only fix more ABEI to realize self-enhanced ECL signal amplification, but also facilitate ion diffusion and efficient utilization of catalytic materials, realizing rapid electron transfer and zero-distance catalysis, significantly improving the initial signal of ECL sensor. Moreover, the most attractive aspect is that Au@PEI-ABEI@Pt hydrogels with good biocompatibility can achieve widespread application of CRISPR/Cas12a in solid-phase carriers without affecting the sensitivity, specificity and shearing activity of CRISPR/Cas12a. After coupling with the ECL system and CRISPR/Cas12a signal amplification strategy, the Au@PEI-ABEI@Pt can achieve an ultrasensitive ECL assay of B. pseudomallei with the LOD of 5 CFU mL−1 in complex samples, with high specificity and stability to effectively classify B. pseudomallei and other Gram-negative bacteria. This study shows that the developed porous hydrogel materials not only serve as an excellent ECL signal reporter to significantly improve the detection sensitivity of ECL biosensors, but also provide a new approach for the wide application of CRISPR/Cas systems in solid-phase carriers.

Single-atom iron boosts electrochemiluminescence for ultrasensitive carcinoembryonic antigen detection.

Asimple and ultrasensitive sandwich-type electrochemiluminescence (ECL) immunosensor has been developedusing porous three-dimensional gold nanoparticles (Au NPs) iron(Fe)-zinc(Zn) metal-organic frameworks (Au NPs-FeZn-MOFs@luminol) as high-efficiency ECL signal probes with Fe single-atom catalysts (SACs) (Fe-N-C SACs) as potentially advanced coreaction accelerators and dissolved oxygen as a coreaction agent to realize an H2O2-free amplification method for detecting carcinoembryonic antigen (CEA). The cathodic ECL of luminol, which was usually negligible, increased first. Because the Fe-N-C SACs exhibited an outstanding catalytic performance and a unique electronic structure, different reactive oxygen species (ROS) were generated via the oxygen reduction reaction. ROS oxidized the luminol anions to luminol anion radicals, preventing the time-consuming luminol electrochemical oxidation. Furthermore, the luminol anion radicals generated in situ reacted with ROS to produce potent cathodic ECL emissions. The immunosensor exhibited favorable analytical accuracy (detection range: 0.1 pg mL-1-80 ng mL-1), and its detection limit for serum samples was 0.031 pg mL-1 (S/N = 3). Consequently, the proposed strategy offers a new approach for early screening of CEA.

Porous boron-doped graphitic carbon nitride-based label-free electrochemical immunoassay of vascular endothelial cadherin.

As a main connecting protein between endothelial cells, vascular endothelial cadherin (CD144) is involved in regulating vascular remodeling and maintaining vascular integrity. It is regarded as a marker of endothelial dysfunction and injury. Quantitative determination of CD144 is of importance in pathology research, diagnosis and treatment of vascular diseases. A label-free electrochemical method for the immunoassay of CD144 was developed in this work. CD144 antibodies were assembled on a glassy carbon electrode modified with porous boron-doped carbon nitride (B-GCN) and gold nanoparticles (AuNPs) in the presence of protein A. The binding of CD144 on the antibody-modified electrode induced serious steric hindrance, inhibiting the diffusion of ferri-/ferrocyanide from the bulk electrolyte to the electrode interface. The change of the differential pulse voltammetric response displayed a linear relationship with the concentration of CD144 between 0.500 and 400 ng mL-1. The new electrochemical sensor showed some good performances including good selectivity, high stability and satisfactory reproducibility. The cellular morphology observation and activity measurement showed that the dysfunction of vascular endothelial cells appeared in the presence of high-content NaCl. The electrochemical analysis reveals a positive correlation between the release amount of CD144 from the dysfunctional cells and the NaCl concentration in the growth medium.

Clay-based durable catalyst membranes of porous layered double hydroxide and gold nanoparticle nanocomposites for fast and continuous-flow reactions

We synthesized the hybrid catalyst of a porous layered double hydroxide (LDH) decorated with ultrasmall Au nanoparticles. The porous LDH was prepared by coprecipitation and ethanol washing, producing thin LDH nanoplatelets. Thereafter, spray drying was carried out, affording a few hundred nm of the hydrangea-like structure of the LDH with an extensive open network and a Brunauer–Emmett–Teller surface area of 386 m2/g. Its sizable open frame and active hydroxide surface enabled the uniform decoration of average 4-nm-diameter Au nanoparticles (Au/P-LDH) through one-pot chemical reduction using NaBH4 at room temperature. We applied the Au/P-LDH for the fabrication of catalyst membranes, which are potentially valuable for the continuous flow of catalytic reactions, e.g., the hydrogenation of p-nitrophenol. This study suggested that their porous structure and active Au nanoparticle catalyst allowed fast and mass catalytic functions by simple filtration without washing or catalyst recovery steps. We found no significant damage to the hybrid membrane during the reactions with a few liters; thus, we expect strong bindings of the Au nanoparticles on the surface of the porous LDH.

Anti HER-2 aptamer functionalized gold nanoparticles of dasatinib for targeted chemo-radiotherapy in breast cancer cells

In the present study, gold nanoparticles functionalized with anti HER-2 aptamer were designed for effective targeted delivery of dasatinib (DSB) to breast cancer cells. Anti HER-2 aptamer attached to porous or plain gold nanoparticles were compared for dasatinib delivery. Activated drug with succinic anhydride and L-cysteine linker was used for conjugation of DSB to gold nanoparticles. The loading efficiency of the activated drug on plain and porous gold nanoparticles was 52 and 68 %, respectively, which was significantly more than the loading of free DSB in gold nanoparticles (1–2.5 %). The anti HER-2 aptamer was conjugated to porous gold nanoparticles loaded with the activated drug. Various characterization techniques such as FESEM, TEM, AFM, zeta potential and ICP-MS were used to confirm the binding of the drug to gold nanoparticles. 1HNMR and FTIR spectroscopic analyses were employed to examine the structural characteristics of the conjugated drug. These analytical techniques confirmed the successful incorporation of succinyl and thiol groups onto the drug molecule. The amount of aptamer binding to different types of gold nanoparticles was obtained from the intensity of the light emitted from the bands observed in electrophoresis gel and due to the presence of porosity in porous gold nanoparticles, the amount of aptamer conjugation on porous gold nanoparticles increased compared to plain ones. Cell cytotoxicity and cellular uptake were evaluated by MTT assay and TEM in BT-474 and MCF-7 cells. Aptamer-functionalized porous gold nanoparticles containing activated dasatinib showed higher cytotoxicity and cellular uptake than modified DSB-loaded nanoparticles and un-activated DSB. The combination of radiation therapy with the modified dasatinib attached to porous gold nanoparticles and aptamer demonstrated a notable reduction in the IC50 values for both the BT-474 and MCF-7 cell lines. Specifically, the IC50 value for the BT-474 cells decreased from 6.95 μM (for unmodified dasatinib) to 2.57 μM, while for the MCF-7 cells, it decreased from 13.97 μM to 8.57 μM. These findings indicate a significant improvement in the efficacy of the modified dasatinib compared to its unmodified counterpart when used in conjunction with radiation therapy.

Qualitative assessment on cisplatin loaded CeO2/Au/GO hybrid as theranostics platform in HeLa cell lines

Nanomaterials have been increasingly popular in bioimaging and cancer therapy due to their unique characteristics to reachtarget-specific tumours. Due to this uniqueness, a drug delivery platform made of nanomaterials has been developed to deliver theanti-cancer drug to target sites. As the number of incidences of cancer increases, it is critical to provide a medication delivery platform for treating cancer as soon as possible. Also, nanosystems based on carbon have been widely used as a possible biomarker for cancer imaging and therapeutics. This research work primarily focuses on the development of a spherical-shaped porous CeO2/Au/GO hybrid nanocomposite to serve as a nanoplatform to treatcervical cancer. The stacked layer of graphene oxide (GO) was loaded with porous aminated cerium oxide nanoparticles (CeO2 NPs) and gold nanoparticles (Au NPs). X-ray Diffraction (XRD),Field Emission Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) were used to investigate their physio-chemical properties and morphology. Furthermore, HeLa cells were interacted with the suggested porous Au/GO hybrid, CeO2/Au/GO hybrid nanosystem and cisplatin-loaded CeO2/Au/GO hybrid system (CeO2/Cis-Au/GO hybrid), under in-vitro conditions to assess the anti-cancer efficacy of the proposed nanoplatforms. In this study, the minimum concentration of Au/GO at which nearly 50% of the cells remain dead (IC50 concentration)is considered to be 62.5 µg/mL and 31.2 µg/mL for CeO2/Au/GO. Further, the cisplatin anticancer drug was chemically bonded with CeO2/Au/GO hybrid nanosystem for testing the apoptotic efficacy of cancer cells under in-vitro conditions. The IC50 value was 62.5 µg/mL which affirmed the anticancer property of the CeO2/Cis-Au/GO system with HeLa cells. According to the findings from the antiproliferative assay, CeO2/Au/GO nanoplatforms resulted in superior cytotoxicity effects on cervical cancer in comparison with CeO2/Cis-Au/GO and Au/GO nanoplatform. Lastly, the proposed CeO2/Au/GO hybrid nanosystem was subject to dual staining investigation using Acridine Orange/Ethidium Bromide (AO/EB) dyes for recording the morphological changes incurred and also to visualize live and dead cells using fluorescence spectroscopy. Based on these findings, the developed CeO2/Au/GO hybrid nanosystem can be taken to in vivo studies for the validation to act as a theranostic platform for cervical cancer.

Exploration of active sites of ethyl alcohol electro-oxidation on porous gold nanoparticles with enhanced Raman spectroscopy.

Novel porous gold nanospheres are prepared by calcination of the gold-urea complexes. The enhanced Raman spectra of ethanol catalyzed by different doses of porous gold nanospheres are measured with a 532 nm laser as the excitation source, and an enhanced charge coupled device served in spectral detection and microscopic imaging. The electrochemical experiments show that the catalytic oxidation products of ethanol with porous gold nanoparticles are acetaldehyde, acetic acid, and water, which further proved that the porous gold nanoparticles can activate the -CH2 of ethanol.

A study on fabrication of SERS substrates base on porous Si nanostructures and gold nanoparticles

A study on fabrication of SERS substrates base on porous Si nanostructures and gold nanoparticles

Aptamer affinity-based microextraction in-line coupled to capillary electrophoresis mass spectrometry using a porous layer/nanoparticle -modified open tubular column

An aptamer affinity based microextraction column is developed to be directly in-line coupled to capillary electrophoresis-mass spectrometry (CE-MS) for analyzing mycotoxins in food samples. Single-stranded DNA aptamers for selective recognition of aflatoxin B1 (AFB1) and ochratoxin A (OTA) targets are co-immobilized via covalent bonds on the surface of the inlet end of a capillary, which is pre-modified with three-dimensional porous layer and gold nanoparticles to enhance the specific surface area and loading capacity. The outlet of the capillary is designed as a porous tip to serve as the spray source for injection to the mass spectrometry. All the necessary processes for pretreatment and analysis of a sample are accomplished in one injection, including aptamer affinity-based microextraction, CE separation and MS detection of analytes. AFB1 and OTA are simultaneously determined in a wide linear range with sample consumption of only 1 μL and the limit-of-detection as low as 1 pg/mL. The microextraction column exhibits excellent repeatability and stability, which can be used over 45 runs within a month with CE separation efficiency and only MS intensity slightly decreased. Mycotoxins in three kinds of cereal based infant foods are accurately analyzed using the proposed method. The study provides a robust and universal approach that would have potential applications in a variety of analytical fields based on selective molecular recognition coupling to CE-MS analysis.

Nanogold morphologies with the same surface chemistry provoke a different innate immune response: An in-vitro and in-vivo study

Gold nanomaterials (GNMs) have unique optical properties with less antigenicity, and their physicochemical properties have strong relation with an immunological response at bio-interface including antigenicity. An interpretation of this correlation would significantly impact on the clinical and theranostic applications of GNMs. Herein, we studied the effect of GNMs morphology on the cytotoxicity (in-vitro), innate immune responses, hepatotoxicity, and nephrotoxicity (in-vivo studies) using gold nano-cups (GNCs), porous gold nanospheres (PGNSs) and solid gold nano particles (SGNPs) coated with the same ligand to ensure similar surface chemistry. The cytotoxicity was assessed via sulfo-rhodamine B (SRB) assay, and the cytotoxicity data showed that morphological features at nanoscale dimensions like surface roughness and hollowness etc. have a significant impact on cellular viability. The biochemical and histopathological study of liver and kidney tissues also showed that all GNMs did not show any toxicity even at high concentration (100 μL). The relative quantification of cytokine gene expression of TNF-α, IFN-γ, IL-4, 1L-6, and 1L-17 (against each morphology) was checked after in-vivo activation in mice. Among the different nanogold morphologies, PVP stabilized GNCs (PVP-GNCs) showed the highest release of pro-inflammatory cytokines, which might be due to their high surface energy and large surface area for exposure as compared to other nanogold morphologies studied. The pro-inflammatory cytokine release could be suppressed by coating with some anti-inflammatory polymer, i.e., inulin. The in-vitro results of pro-inflammatory (TNF-α, IL-1) cytokines also suggested that all GNMs may induce activation of macrophages and Th1 immune response. The in-vivo activation results showed a decrease in mRNA expression of the cytokines (TNF-α, IFN-γ, IL-4, 1L-6 and 1L-17). Based on these findings, we proposed that the shape and morphology of GNMs control their immune response at nano-bio interface, and it must be considered while designing their role for different biomedical applications like immuno-stimulation and bio-imaging.

Open Tubular Capillary Electrochromatography-Mass Spectrometry for Analysis of Underivatized Amino Acid Enantiomers with a Porous Layer-Gold Nanoparticle-Modified Chiral Column.

By developing a novel chiral column, we integrate open tubular capillary electrochromatography into sheathless mass spectrometry (MS) for efficient analysis of underivatized amino acid enantiomers. The chiral column is easily fabricated by modifying the inner surface of a capillary with a three-dimensional porous layer (PL, thickness ∼ 90 nm, pore size ∼ 30 nm) and gold nanoparticles and by introducing a chiral selector, thiol β-cyclodextrin (SH-β-CD), onto the modified surface via Au-S bonds. This approach greatly enhances the specific surface area and thus the ratio of the stationary phase to mobile phase and interaction between the stationary phase and analytes. The proposed PLOT@Au@CD column is coupled to the sheathless CE-ESI-MS system for chiral analysis of amino acid enantiomers. No derivatization of amino acids is required for chiral analysis, and baseline separation of a total of 15 pairs of amino acid enantiomers is achieved within 17 min with high column efficiencies of 5.60 × 104 to 1.82 × 106 N/m, high resolutions of 1.51-10.0, and low limits of detection between 0.02 and 0.09 μg/mL. The separation efficiency and MS intensity are only slightly decreased over 60 runs or after usage for 15 days, showing excellent repeatability and stability of the PLOT@Au@CD column. The proposed method is successfully applied to the determination of amino acid enantiomers in vinegar samples with satisfactory accuracy. Our study provides a new approach for developing a chiral stationary phase in the chromatographic separation technique, which can be easily coupled to sensitive MS detection, thus it would be of value for various applications in the fields of chiral analysis.

Porous spherical gold nanoparticles via a laser induced process.

Nanoparticles consisting of a mixture of several metals and also porous nanoparticles due to their special structure exhibit properties that find applications in spectroscopic detection or catalysis. Different approaches of top down or bottom up technologies exist for the fabrication of such particles. We present a novel combined approach for the fabrication of spherical porous gold nanoparticles on low-cost glass substrates under ambient conditions using a UV-laser induced particle preparation process with subsequent wet chemical selective etching. In this preparation route, nanometer-sized branched structures are formed in spherical particles. The laser process, which is applied to a silver/gold bilayer system with different individual layer thicknesses, generates spherical mixed particles in a nanosecond range and influences the properties of the fabricated nanoparticles, such as the size and the mixture and thus the spectral response. The subsequent etching process is performed by selective wet chemical removal of silver from the nanoparticles with diluted nitric acid. The gold to silver ratio was investigated by energy-dispersive X-ray spectroscopy. The porosity depends on laser parameters and film thickness as well as on etching parameters such as time. After etching, the surface area of the remaining Au nanoparticles increases which makes these particles interesting for catalysis and also as carrier particles for substances. Such substances can be positioned at defined locations or be released in appropriate environments. Absorbance spectra are also analyzed to show how the altered fractured shape of the particles changes localized plasmon resonances of the resultingt particles.

Fabrication of porous noble metal nanoparticles based on laser ablation toward water and dealloying for biosensing

Porous noble metal nanoparticles (NPs) have been widely applied in biosensing owing to the excellent properties of the localized surface plasmon resonance (LSPR), catalytic and large surface-to-volume ratio. A fabrication strategy combining laser ablation toward water (LATW) with dealloying was developed for easy preparation of porous noble metal NPs, especially porous gold NPs (pAu NPs) and porous platinum NPs (pPt NPs) for biosensing. pAu NPs were explored for the surface-enhanced Raman scattering (SERS) detection of rhodamine 6G, achieving a detection limit of 10-8 M rhodamine 6G and the enhancement factor of 4.3 × 105. Moreover, based on the azo reaction between 4-aminothiophenol with nitrite, nitrite in the concentration range of 20 ∼ 100 μM was precisely detected by SERS of pAu NPs. pPt NPs were modified on the working electrode for the electrochemical sensing. Compared with Pt NPs and Pt/Ag NPs, pPt NPs modified electrode exhibited the best H2O2 detection performance with a good linear range of 0 ∼ 52.5 mM H2O2 and a good stability for one month. The well integration of LATW with dealloying provides an effective strategy for fabrication of various porous metal NPs, which are potentially applied in imaging, photothermal, drug delivery, molecular sensing and so on.

Gold-incorporated porous hollow carbon nanofiber for reversible magnesium-metal batteries

Rechargeable magnesium-metal batteries have received ever-increasing attention as potential alternatives to current Li-ion batteries. Although the most relevant studies have mainly focused on exploring compatible electrolyte and cathode materials, relatively less attention has been paid to the development of an efficient anode host. Herein, we propose a unique anode host with a porous hollow carbon nanofiber structure and gold nanoparticles incorporated in the interior (Au@PCNF). Using the dual-nozzle electrospinning technique, a porous web body was configured with the hierarchical network of hollow carbon nanofibers, with the interior of each string specially designed to embed Au nanoparticles. We demonstrated that Au nanoparticles can act as magnesiophilic sites for Mg plating; therefore, we decorated the magnesiophilic seeds inside the hollow nanofibers to efficiently attract newly deposited Mg metal. The unique feature of Au@PCNF not only reduced the nucleation overpotentials for Mg plating but also guided the even deposition of Mg metal on the substrate. As a result, Au@PCNF exhibited stable and long-term cycle performance with enhanced adhesion property for the newly deposited Mg metal compared with other controls. This novel structural design is promising for the development of efficient anode hosts for magnesium-metal batteries, which will help open an avenue for the practical application of multivalent-ion batteries.

Synthesis of Porous Polydimethylsiloxane Gold Nanoparticles Composites by a Single Step Laser Ablation Process

Typically, polymeric composites containing nanoparticles are realized by incorporating pre-made nanoparticles into a polymer matrix by using blending solvent or by the reduction of metal salt dispersed in the polymeric matrix. Generally, the production of pre-made Au NPs occurs in liquids with two-step processes: producing the gold nanoparticles first and then adding them to the liquid polymer. A reproducible method to synthetize Au nanoparticles (NPs) into polydimethylsiloxane (PDMS) without any external reducing or stabilizing agent is a challenge. In this paper, a single-step method is proposed to synthetize nanoparticles (NPs) and at the same time to realize reproducible porous and bulk composites using laser ablation in liquid. With this single-step process, the gold nanoparticles are therefore produced directly in the liquid polymer. The optical properties of the suspensions of AuNPs in distilled water and in the curing agent have been analyzed by the UV-VIS spectroscopy, employed in the transmission mode, and compared with those of the pure curing agent. The electrical dc conductivity of the porous PDMS/Au NPs nanocomposites has been evaluated by the I–V characteristics. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis have monitored the composition and morphology of the so-obtained composites and the size of the fabricated Au nanoparticles. Atomic force microscopy (AFM) has been used to determine the roughness of the bulk PDMS and its Au NP composites.

A novel screening on the specific peptide by molecular simulation and development of the electrochemical immunosensor for aflatoxin B1 in grains

In this work, based on a specific antibody was obtained from the Protein Data Bank (PDB), a library of the specific peptides of aflatoxin B1 (AFB1) was constructed by combining key amino acids, amino acid mutations and molecular docking. Then, the porous gold nanoparticles (porous AuNPs) were fabricated on the surface of a glassy carbon electrode (GCE). A novel, sensitive and no-label signal immunosensor was developed by signal enhancement with the specific peptide as the recognition element for the detection of AFB1 in cereals. Under the optimal conditions, the limit of detection (S/N = 3) was 9.4 × 10−4 μg·L−1, and the linear range was 0.01 μg·L−1 to 20 μg·L−1. The recovery results were 88.4%∼102.0%, which indicated an excellent accuracy. This sensor is an ideal candidate for screening the peptides of AFB1, and a novel immunosensor was used to detect AFB1 in cereals.

Fabrication of a surface-enhanced Raman spectroscopy-based analytical method consisting of multifunctional DNA three-way junction-conjugated porous gold nanoparticles and Au-Te nanoworm for C-reactive protein detection.

C-Reactive protein (CRP) is a biomarker of inflammatory responses and an index for assessing the risk of cardiovascular disease and estimating prognosis. In this study, we constructed a surface-enhanced Raman spectroscopy (SERS) biosensor composed of a multifunctional DNA three-way junction (DNA 3WJ), porous gold nanoplates (pAuNPs), and an Au-Te nanoworm structure for detection of CRP. The pAuNP and Au-Te nanostructures were synthesized by galvanic replacement reactions, and the morphology was confirmed by transmission electron microscopy, scanning electron microscopy, and dynamic light scattering (DLS). To generate the SERS signal, the Au-Te nanostructure was immobilized on an indium-tin oxide substrate, and the thiol-modified CRP aptamer was then self-assembled onto the modified substrate for CRP recognition. To amplify the SERS signal and identify the Raman tag, the multifunctional DNA 3WJ was conjugated with the pAuNPs, and each fragment of 3WJ was functionalized to biotin (pAuNP conjugation), methylene blue (Raman reporter), and CRP aptamer (target binding). The results were confirmed by gel electrophoresis. For conjugation between pAuNPs and DNA 3WJ, avidin was encapsulated in pAuNPs, and the conjugation structure was confirmed by DLS. The fabricated SERS biosensor showed detection limits of 2.23 pM in phosphate-buffered saline and 3.11 pM in diluted human serum. Overall, the proposed biosensor may have potential applications as a SERS biosensor platform.

Porous biomass carbon and gold nanoparticles modified electrode for myoglobin direct electrochemistry and electrocatalysis

AbstractIn this paper, a stable porous biomass carbon (BC) and gold (Au) nanoparticles modified carbon ionic liquid electrode (CILE) was prepared for the investigation of direct electrochemistry and electrocatalysis of myoglobin (Mb). BC was synthesized via pyrolysis of Hainan's natural tropical plant Lagerstroemia indica leaves, which was modified on the surface of CILE with Au nanoparticles further electrodeposited on the electrode surface. Then, Mb was cast on the nanocomposite‐modified electrode to obtain an electrochemical sensing platform with Nafion film (Nafion/Mb/Au−BC/CILE). Direct electrochemistry of Mb on the modified electrode was investigated with appearance of a pair of enhanced redox peaks, indicating direct electron transfer rate of Mb was accelerated due to the presence of Au−BC nanocomposite. Au−BC nanocomposite exhibited high conductivity, good biocompatibility, and large surface area, which was beneficial for electron transfer of Mb. The Mb modified electrode showed excellent electrocatalytic activity toward the reduction of trichloroacetic acid (TCA) and sodium nitrite (NaNO2), which was further used to establish a new electroanalytical method with satisfied sensitivity in real samples analysis.