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On some occasions, such as new energy clinics, monitoring the trace hydrogen at the ppb level is necessary. The traditional resistive hydrogen sensors based on the Pd alloys are very difficult to realize such an extremely low detection limit. To achieve a detection limit at the ppb level and also ensure good stability, a MEMS hydrogen sensor was designed in a suspended Wheatstone bridge structure, with all four resistive arms defined on a sputtered Pd-Au alloy thin film. For the Wheatstone bridge sensor, absolute response ( R a ) and relative response ( R s ) are defined to describe the sensitivity of the sensor, and the effect of annealing temperature on baseline drift is investigated using the baseline zero drift parameter (DBZD). By testing the sensors across a hydrogen concentration range of 20 ppb to 3 v/v%, the optimal annealing temperature (250 °C) and operating temperature (60 °C) were identified. Under these conditions, the sensor exhibited a detection limit as low as 20 ppb with a power consumption of only 4.6 mW. At the same time, the response and recovery times of the sensor were 6 and 19 s, respectively, toward 3 v/v% hydrogen. After testing over a 100-day period, R a fluctuated only 0.0026%, indicating that the hydrogen sensor had good long-term stability for low-concentration detection. More results also showed that the sensor has good repeatability, selectivity, and humidity resistance. With the wide measurement range (20 ppb to 3 v/v%), the sensor has the potential to meet hydrogen detection requirements in multiple scenarios.

In this study, we have developed a novel, hypersensitive, and ultraselective electrochemical sensor containing thermally annealed gold-silver alloy nanoporous matrices (TA-Au-Ag-ANpM) integrated with f-MWCNTs-CPE and poly(l-serine) nanocomposites for the simultaneous detection of sulfathiazole (SFT) and sulfamethoxazole (SFM) residues in honey, beef, and egg samples. TA-Au-Ag-ANpM/f-MWCNTs-CPE/poly(l-serine) was characterized using an extensive array of analytical (UV-Vis, FT-IR, XRD, SEM, and EDX), and electrochemical (EIS, CV and SWV) techniques. It exhibited outstanding performance over a wide linear range, from 4.0 pM to 490 μM for SFT and 4.0 pM to 520 μM for SFM, with picomolar detection and quantification limits (0.53 pM and 1.75 pM for SFT, 0.41 pM and 1.35 pM for SFM, respectively). The sensor demonstrated exceptional repeatability, reproducibility, and anti-interference capability, with percentage recovery of 95.6-102.4% in food samples and RSD below 5%. Therefore, the developed sensor is an ideal tool to address the current antibiotic residue crisis in food sources., Competing Interests: Declaration of competing interest We want to affirm that there are no recognized conflicts of interest associated with this publication, and this study has not received dedicated funding from any public, commercial, or non-profit sector funding entity. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)

Developing new low modulus structures is important for reducing the risk of aseptic loosening during loading of implant materials. However, an alloy that may also confer some advantage at preventing septic loosening could dramatically improve the outcomes for patients. Nevertheless, the predictive power of current models remains limited to common alloying additions. As such, this study considers the mechanical properties of a range of Ti-Nb-Au superelastic alloys to elucidate the composition range for which low modulus structures can be achieved. These modulus values are compared to other critical design parameters such as strain recovery and strength. It was found that Au additions are effective at suppressing the formation of the ω phase and allow alloys with lower moduli to be achieved. It was also shown that low β phase stability is critical for achieving the lowest modulus, and that this susceptibility to transform to a martensite may enable higher strengths to be achieved. However, this low β phase stability also limits the strain recovery that may be achieved meaning these two properties are not necessarily independently tuneable. These data provide important context for the design of new systems containing unusual alloying additions such as Au., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in widespread disease transmission, challenging the stability of global healthcare systems. Surface-enhanced Raman scattering (SERS) as an easy operation, fast, and low-cost technology illustrates a good potential in detecting SARS-CoV-2. In the study, one-step fabrication of gold-silver alloy nanoparticles (AuAgNPs) with adjustable metal proportions and diameters is employed as SERS substrates. The angiotensin-converting enzyme 2 (ACE2) functionalized AuAgNPs are applied as sensor surfaces to detect SARS-CoV-2 S protein. By optimizing the SERS substrates, ACE2/Au 35 Ag 65 NPs illustrate higher performance in detecting the SARS-CoV-2 S protein with a limit of detection (LOD) of 10 fg/mL in both phosphate-buffered saline (PBS) and pharyngeal swabs solution (PSS). It also provides excellent reproducibility with a relative standard deviation (RSD) of 7.7 % and 7.9 %, respectively. This easily preparable and highly reproducible SERS substrate has good potential in the practical application of detecting SARS-CoV-2., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Implant infections are a major challenge for the healthcare system. Biofilm formation and increasing antibiotic resistance of common bacteria cause implant infections, leading to an urgent need for alternative antibacterial agents. In this study, the antibiofilm behaviour of a coating consisting of a silver (Ag)/gold (Au) nanoalloy is investigated. This alloy is crucial to reduce uncontrolled potentially toxic Ag + ion release. In neutral pH environments this release is minimal, but the Ag + ion release increases in acidic microenvironments caused by bacterial biofilms. We perform a detailed physicochemical characterization of the nanoalloys and compare their Ag + ion release with that of pure Ag nanoparticles. Despite a lower released Ag + ion concentration at pH 7.4, the antibiofilm activity against Escherichia coli (a bacterium known to produce acidic pH environments) is comparable to a pure nanosilver sample with a similar Ag-content. Finally, biocompatibility studies with mouse pre-osteoblasts reveal a decreased cytotoxicity for the alloy coatings and nanoparticles.

Excessive intake of estrogen poses significant health risks to the human body; hence, there is a necessity to develop rapid detection methods to monitor its levels of addition. Gold nanoparticles (AuNPs), commonly utilized as colorimetric signal labels, find extensive application in lateral flow immunoassay (LFIA). However, the detection sensitivity of traditional AuNPs-LFIA is typically constrained by low molar extinction coefficients and reliance on a single signal. Herein, in this work, unique spark-type AuCuPt nanoflowers modified with tannic acid (AuCuPt@TA) were precisely designed by reasonable layer-by-layer element composition and green modification. The obtained AuCuPt displays robust broadband absorption spanning the visible to near-infrared spectrum, showcasing a notable molar extinction coefficient of 2.38 × 10 12 M -1 cm -1 and a photothermal conversion efficiency of 48.5%. Based on this, selecting estriol (E 3 ) as a model analyte, colorimetric/photothermal dual-signal LFIA (CLFIA and PLFIA) was developed. Limits of detection (LOD) of the CLFIA and PLFIA were achieved at 0.033 ng mL -1 and 0.021 ng mL -1 , respectively, which represent a 9.3- and 14.6-fold improvement compared to the visual LOD of AuNPs-LFIA. Moreover, the application feasibility of the immunoassay was further evaluated in the milk and pork with satisfactory recoveries ranging from 86.21% to 117.91%. Thus, this work has enhanced the performance of LFIA for E 3 detection and exhibited enormous potential for other sensing platform construction.

Bimetallic iron-noble metal alloy nanoparticles have emerged as promising contrast agents for magnetic resonance imaging (MRI) due to their biocompatibility and facile control over the element distribution. However, the inherent surface energy discrepancy between iron and noble metal often leads to Fe atom segregation within the nanoparticle, resulting in limited iron-water molecule interactions and, consequently, diminished relaxometric performance. In this study, we present the development of a class of ligand-induced atomically segregation-tunable alloy nanoprobes (STAN) composed of bimetallic iron-gold nanoparticles. By manipulating the oxidation state of Fe on the particle surface through varying molar ratios of oleic acid and oleylamine ligands, we successfully achieve surface Fe enrichment. Under the application of a 9 T MRI system, the optimized STAN formulation, characterized by a surface Fe content of 60.1 at %, exhibits an impressive r 1 value of 2.28 mM -1 ·s -1 , along with a low r 2/ r 1 ratio of 6.2. This exceptional performance allows for the clear visualization of hepatic tumors as small as 0.7 mm in diameter in vivo , highlighting the immense potential of STAN as a next-generation contrast agent for highly sensitive MR imaging.

The exploration into nanomaterial-based nonenzymatic biosensors with superb performance in terms of good sensitivity and anti-interference ability in disease marker monitoring has always attained undoubted priority in sensing systems. In this work, we report the design and synthesis of a highly active nanocatalyst, i.e., palladium and platinum nanoparticles (Pt&Pd-NPs) decorated ultrathin nanoporous gold (NPG) film, which is modified on a homemade graphene paper (GP) to develop a high-performance freestanding and flexible nanohybrid electrode. Owing to the structural characteristics the robust GP electrode substrate, and high electrochemically catalytic activities and durability of the permeable NPG support and ultrafine and high-density Pt&Pd-NPs on it, the resultant Pt&Pd-NPs-NPG/GP electrode exhibits excellent sensing performance of low detection limitation, high sensitivity and anti-interference capability, good reproducibility and long-term stability for the detection of small molecular biomarkers hydrogen peroxide (H 2 O 2 ) and glucose (Glu), and has been applied to the monitoring of H 2 O 2 in different types of live cells and Glu in body fluids such as urine and fingertip blood, which is of great significance for the clinical diagnosis and prognosis in point-of-care testing.

Background: Limited chemotherapy efficacy and cancer stem cells (CSCs)-induced therapeutic resistance are major difficulties for tumour treatment. Adopting more efficient therapies to eliminate bulk-sensitive cancer cells and resistant CSCs is urgently needed., Methods: Based on the potential and functional complementarity of gold and silver nanoparticles (AuNPs or AgNPs) on tumour treatment, bimetallic NPs (alloy) have been synthesized to obtain improved or even newly emerging bioactivity from a combination effect. This study reported a facile, green and economical preparation of Au-Ag alloy NPs using biocompatible polydopamine (PDA) as a reductant, capping, stabilizing and hydrophilic agent., Results: These alloy NPs were quasi-spherical with rough surfaces and recorded in diameters of 80 nm. In addition, these alloy NPs showed good water dispersity, stability and photothermal effect. Compared with monometallic counterparts, these alloy NPs demonstrated a dramatically enhanced cytotoxic/pro-apoptotic/necrotic effect towards bulk-sensitive MCF-7 and MDA-MB-231 cells. The underlying mechanism regarding the apoptotic action was associated with a mitochondria-mediated pathway, as evidenced by Au3+/Ag+ mediated Mitochondria damage, ROS generation, DNA fragmentation and upregulation of certain apoptotic-related genes (Bax, P53 and Caspase 3). Attractively, these Au-Ag alloy NPs showed a remarkably improved inhibitory effect on the mammosphere formation capacity of MCF-7 CSCs., Conclusion: All the positive results were attributed to incorporated properties from Au, Ag and PDA, the combination effect of chemotherapy and photothermal therapy and the nano-scaled structure of Au-Ag alloy NPs. In addition, the high biocompatibility of Au-Ag alloy NPs supported them as a good candidate in cancer therapy., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

The structure transformation between Au-Pd alloy and core-shell icosahedral nanoparticles was achieved by a one-step aqueous-phase strategy. This strategy provided a way to tune the structure and atomic distribution of Au-Pd icosahedral nanoparticles. It could modulate the electronic structure of Pd, achieving promoted electrocatalytic ability toward the hydrogen evolution reaction.

Bimetallic or alloy nanoparticles (NPs) have improved properties compared to their monometallic forms. Microalgae being rich in biocompatible reductants and being ecofriendly are potential sources to synthesize fuctionalized NPs. In this study, biosynthesis of silver, gold, and bimetallic NPs was carried out via bioreduction using aqueous extract of algal isolate Chlorella acidophile , inhabitant of non-arable land. C. acidophile is known to contain highly bioactive functional moieties, which can serve as nanobiofactories for metallic NPs. Various characterization techniques viz, UV-visible spectrophotometer, X-ray diffraction analysis, X-ray photo-electron spectroscopy, and Raman spectroscopy were employed to determine their composition, structure, and crystal phase. The monometallic and bimetallic particles were found to be crystalline state and generally in a spherical shape. Their size ranged from 5 to 45 nm and the corresponding FTIR spectra indicated that the specific organic functional groups from algal extract were involved in the bio-reduction. Furthermore, the core-shell in the case of Au-Ag NPs was formed due to the simultaneous reduction of gold and silver ions. An enhanced and more pronounced Raman spectra of Au-Ag NP compared to individual Au NP indicated the improved properties of bimetallic NPs, the latter having been of immense potential to be used as sensors in industries.

Here, we describe the surprising reactivity between surface-attached (a) 0.9, 1.6, and 4.1 nm diameter weakly stabilized Au nanoparticles (NPs) and aqueous 1.0 × 10 -4 M Ag + solution, and (b) 1.6 and 4.1 nm diameter weakly stabilized Au NPs and aqueous 1.0 × 10 -5 M PtCl 4 2- , which are considered to be antigalvanic replacement (AGR) reactions because they are not thermodynamically favorable for bulk-sized Au under these conditions. Anodic Stripping Voltammetry (ASV) and Scanning Transmission Electron Microscopy with Energy-Dispersive X-ray Spectroscopy (STEM-EDS) mapping provide quantitation of the extent of Ag and Pt replacement as a function of Au NP diameter. The extent of the reaction increases as the Au NP size decreases. The percentage of Ag in the AuAg alloy following AGR based on ASV is 17.8 ± 0.6% for 4.1 nm diameter Au NPs, 87.2 ± 2.9% for 1.6 nm Au NPs, and an unprecedented full 100% Ag for 0.9 nm diameter Au NPs. STEM-EDS mapping shows very close agreement with the ASV-determined compositions. In the case of PtCl 4 2- , STEM-EDS mapping shows AuPt alloy NPs with 3.9 ± 1.3% and 41.1 ± 8.7% Pt following replacement with 4.1 and 1.6 nm diameter Au NPs, respectively, consistent with qualitative changes to the ASV. The size-dependent AGR correlates well with the negative shift in the standard potential (E 0 ) for Au oxidation with decreasing NP size.

Colloidal porous AuAg alloyed nanoparticles (pAuAgNPs) were synthesized by galvanic replacement reaction from Ag nanocubes. pAuAgNPs have a 50 nm exterior diameter and half of their inner space consists of voids that have a bimodal size distribution with peaks at 21 and 8.3 nm. pAuAgNPs showed a plasmonic peak at 750 nm, which was exploited for photoacoustic (PA) imaging. Gold nanorods (AuNRs) were prepared and used as the control; they have a strong plasmonic peak at 720 nm. In in vitro experiments at respective plasmonic peak excitations, pAuAgNPs gave stronger PA signals than AuNRs by 8.9 times per particle and 11.7 times per dosage by exogenous atom. The high surface area per volume as a result of the inner voids amplified the PA signals by efficient thermoacoustic conversion. In experiments of chicken-tissue phantoms, pAuAgNPs showed PA signals through 4.5 cm thick tissue, whereas AuNRs gave no detectable signal. In whole-body in vivo experiments, pAuAgNPs injected into the body showed 2.7 times stronger PA signals than AuNRs. Coating the pAuAgNPs with a silica layer additionally increased their PA signal by 1.8 times when compared to the uncoated ones.

In treatment of hypoxic tumors, oxygen-dependent photodynamic therapy (PDT) is considerably limited. Herein, a new bimetallic and biphasic Rh-based core-shell nanosystem (Au@Rh-ICG-CM) is developed to address tumor hypoxia while achieving high PDT efficacy. Such porous Au@Rh core-shell nanostructures are expected to exhibit catalase-like activity to efficiently catalyze oxygen generation from endogenous hydrogen peroxide in tumors. Coating Au@Rh nanostructures with tumor cell membrane (CM) enables tumor targeting via homologous binding. As a result of the large pores of Rh shells and the trapping ability of CM, the photosensitizer indocyanine green (ICG) is successfully loaded and retained in the cavity of Au@Rh-CM. Au@Rh-ICG-CM shows good biocompatibility, high tumor accumulation, and superior fluorescence and photoacoustic imaging properties. Both in vitro and in vivo results demonstrate that Au@Rh-ICG-CM is able to effectively convert endogenous hydrogen peroxide into oxygen and then elevate the production of tumor-toxic singlet oxygen to significantly enhance PDT. As noted, the mild photothermal effect of Au@Rh-ICG-CM also improves PDT efficacy. By integrating the superiorities of hypoxia regulation function, tumor accumulation capacity, bimodal imaging, and moderate photothermal effect into a single nanosystem, Au@Rh-ICG-CM can readily serve as a promising nanoplatform for enhanced cancer PDT., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Adenosine triphosphate (ATP) plays a crucial role in energy metabolism and extracellular purinergic signaling. A 3D bimetallic Au/Pt nanoflowers decorated ATP microelectrode biosensor prepared by facile and effective template-free electrodeposition was firstly reported, realizing local detection of cellular ATP secretion. The ATP biosensor was developed by co-immobilization of glucose oxidase and hexokinase, exhibiting long-term stability (79.39 ± 9.15% of its initial value remained after 14 days at 4 °C) and high selectivity with a limit of detection down to 2.5 μM (S/N = 3). The resulting ATP biosensor was then used for direct in situ monitoring of ATP secreted from living cells (PC12) with the stimulation of high K + solutions. The obtained current was about 21.6 ± 3.4 nA (N = 6), corresponding to 12.2 ± 2.8 μM ATP released from cells, right in the micromolar range and consistent with the suggested levels. The 3D bimetallic Au/Pt nanoflowers possess excellent catalytic activity and large electroactive surface area, contributing to enzymatic activity preservation and long-term stability. This work provides a promising platform for long-time monitoring of other neurotransmitters and secretions in cellular glycolysis and apoptosis processes in the future., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Nanotechnology provides new tools for gene expression analysis that allow for sensitive and specific characterization of prognostic signatures related to cancer. Cancer is a complex disease where multiple gene loci contribute to the phenotype. The ability to simultaneously monitor differential expression originating from each locus allows for a more accurate indication into the degree of cancerous activity than either locus alone. Metal nanoparticles have been widely used as labels for in vitro identification and quantification of target sequences.Here we describe the synthesis of nanoparticles with different noble metal compositions in an alloy format that are then functionalized with thiol-modified ssDNA (nanoprobes). We also show how such nanoprobes are used in a non-cross-linking colorimetric method for the direct detection and quantification of specific mRNA targets, without the need for enzymatic amplification or reverse-transcription steps. The different metals in the alloy provide for distinct absorption spectra due to their characteristic plasmon resonance peaks. The color multiplexing allows for simultaneous identification of different mRNA targets involved in cancer development. A comparison of the absorption spectra of the nanoprobe mixtures taken before and after induced aggregation of metal nanoparticles allows to both identify and quantify each mRNA target. We describe the use of gold and gold-silver alloy nanoprobes for the development of the non-cross-linking method to detect a specific BCR-ABL fusion gene (e.g., e1a2 and e14a2) mRNA target associated with chronic myeloid leukemia (CML) using 10 ng/μL of unamplified total human RNA. Additionally, we demonstrate the use of this approach for the direct diagnostics of CML. This simple methodology takes less than 50 min to complete after total RNA extraction with comparable specificity and sensitivity to the more commonly used methods.

The coupling between noble metal nanostructures and chiral molecules gives rise to strong chiroptical responses in the range from the ultraviolet (UV) to visible spectrum. In this work, cysteine-modified Au/Ag alloyed nanotubes (ANTs) have been prepared by coupling cysteine with Au/Ag ANTs. The chiroptical responses strongly depend on the chirality of cysteine and show clear mirrored behaviours. In contrast to Ag- or Au-cysteine chiral hybrid nanorods, the cysteine-modified Au/Ag ANTs exhibit higher chiroptical responses due to a stronger local electromagnetic field. The induced CD signals emerge in the interband absorption region of Au/Ag ANTs rather than in the local surface plasmon bands, which can be attributed to both the extended helical network conformation on the surface of Au/Ag ANTs and the near-field enhancement effect of plasmonic nanotubes. This confirms that Coulomb interaction induces coupling between cysteine and Au/Ag ANTs, which allows cysteine molecules to form an extended helical network on the surface of Au/Ag ANTs. Furthermore, the cysteine-modified Au/Ag ANTs also show excellent chiral recognition for amino acids in catalytic electrochemical reactions due to the presence of chiral active sites and the steric effect of large groups.

The continuing emergence of antibiotic-resistant bacteria due to the excessive use of antibiotics has produced a strong demand for novel strategies and new materials that do not lead to bacterial resistance. In the present work silicon nanowire arrays modified with gold-silver alloy nanoparticles (SN-Au/Ag) was investigated as a photo-induced antibacterial material. It was shown that SN-Au/Ag can kill bacteria with high efficiency under sunlight in times of the order of a few minutes, and this is achieved through synergism between photothermal and photocatalytic effects. It appears that the combined effect of heat and reactive oxygen species (ROS) causes bacteria killing through damage to the cell membrane and leakage of cytoplasm contents. Both gold and silver in the alloy nanoparticles are required for the observed bactericidal action. Moreover, the SN-Au/Ag material can be "recycled" without loss of bactericidal activity. It is concluded that the silicon nanowire arrays modified with gold-silver alloy nanoparticles developed in this work has promise as an antibacterial nanomaterial for the development of novel antibiotics.

Composites of the noble metal Au supported on MgAl-LDHs were prepared by a simple impregnation-reduction method to be used as thermal- and photocatalysts for the photocatalytic degradation of ciprofloxacin and thermocatalytic decomposition of formic acid to produce hydrogen. A collection of techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) were employed to determine the structure and morphology properties of the as-prepared Au/MgAl-LDHs. The presence of surface Au(0) in Au/MgAl-LDHs was confirmed by TEM and XPS analyses. For the first time, we compared the effect of the surfactant PVP on the catalyst and found that the Au/MgAl-LDH composite with Au particle size of 2-8 nm had better catalytic activity than the (PVP@Au)/MgAl-LDH composite with Au particle size in the range of 1-5 nm. The sizes of Au NPs in the two catalysts were similar but had different effects on the catalytic performance. This indicated that the addition of PVP had an inhibitory effect on the catalytic activity of the catalyst. To evaluate the photostability of Au/MgAl-LDHs, recycle experiments for the photocatalytic degradation of ciprofloxacin were performed, and it was found that Au/MgAl-LDHs had good stability. Finally, we also applied Au/MgAl-LDHs in environmental catalysis and energy catalysis; we hope that they will be useful in practical applications.

The presented work investigates the chemoresistivity of Au ultrathin films, whose surface is modified by deposition of few monolayers of Au, Pd, or AuPd alloy. The model adsorbate in this study was the HS - ion from 0.1 M NaCl solution having concentrations ranging from 0 to 40 ppm. The Au surface modification was carried out using deposition via surface-limited redox replacement of the underpotentially deposited Pb monolayer. Modified Au films have shown higher chemoresistivity than the pristine ones. Our results and analysis suggest that these improvements are due to increased concentration of surface defects and enhanced scattering cross-section per adsorbate induced by chemical modification of the surface by Pd. The significance of our findings is discussed for practical applications shining more light on the importance of surface preparation for chemoresistive sensor design and performance.

Herein, we developed a simple and rapid strategy to synthesize gold/silver bimetallic nanoclusters (Au/Ag NCs) with highly biochemical stability by a one-pot route. The Au/Ag NCs were obtained via a chemical reduction procedure in alkaline aqueous solution at 75 °C within only 20 min by employing bovine serum albumin (BSA) as both ligand and reductant. The as-obtained Au/Ag NCs displayed bright orange fluorescence with an emission peak located at 570 nm and temperature-dependent fluorescence property, which were utilized as fluorescent thermometer directly. More intriguingly, the Au/Ag NCs were very stable against various pH values, ions, biothiols, H 2 O 2 , fetal bovine serum (FBS), RPMI 1640 medium and amino acids. Taking advantage of the excellent biochemical stability, a ratiometric fluorescence biosensor, fluorescein-5-isothiocyanate (FITC)-Au/Ag NCs, was constructed for pH sensing based on the incorporation of FITC into the Au/Ag NCs. Furthermore, the ratiometric pH sensor was also successfully applied on the model of HeLa cells., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The treatment of massive bone defects is still a significant challenge for orthopedists. Here we have engineered synthetic porous AuPd alloy nanoparticles (pAuPds) as a hyperthermia agent for in situ bone regeneration through photothermal therapy (PTT). After being swallowed by cells, pAuPds produced a mild localized heat (MLH) (40-43 °C) under the irradiation of a near-infrared laser, which can greatly accelerate cell proliferation and bone regeneration. Almost 97% of the cranial defect area (8 mm in diameter) was covered by the newly formed bone after 6 weeks of PTT. RNA sequencing analysis was used to obtain insight into the molecular mechanism of the MLH on cell proliferation and bone formation. These results demonstrated that the Wnt signaling pathway was involved in the MLH. This Letter provides a unique strategy with mild heat stimulation and high efficiency for in situ bone regeneration.

The rapid detection of bacterial strains has become a major topic thoroughly discussed across the biomedical field. Paired with the existence of nosocomial pathogen agents that imply extreme medical and financial challenges throughout diagnosis and treatment, the development of rapid and easy-to-use sensing devices has gained an increased amount of attention. Moreover, antibiotic resistance considered by World Health Organization as one of the "biggest threats to global health, food security, and development today" enables this topic as high priority. Pseudomonas aeruginosa, one of the most ubiquitous bacterial strains, has various quorum-sensing systems that are a direct cause of their virulence. One of them is represented by pyocyanin, a blue pigment with electroactive properties that is synthesized from early stages of bacterial colonization. Thus, the sensitive detection of this biomarker could enable a personalized and efficient therapy. It was achieved with the development of an electrochemical sensor based on a thermosensitive polymer, modified with Au/Ag nanoalloy for the rapid and accurate detection of pyocyanin, a virulence biomarker of Pseudomonas aeruginosa. The sensor displayed a linear range from 0.12 to 25 μM, and a limit of detection of 0.04 μM (signal/noise = 3). It was successfully tested in real samples spiked with the target analyte without any pretreatment other than a dilution step. The detection of pyocyanin with high recovery in whole blood in a time frame of 5-10 min from the moment of collection was performed with this electrochemical sensor. Graphical abstract.

The current approach represents a controllable strategy for studying the antipathogenic effects against selected bacterial strains and fungi for silver nanoparticles and gold nanoparticles versus their bimetallic nano-alloys spontaneously prepared by the same technique. Spontaneous ingraining of silver and gold based monometallic and bimetallic nano-objects was carried out by employing organic polymer of hydroxyethyl cellulose which was presumed to play the dual role of nanogenerator and surfactant, via seed mediated growth technique. Revolution of UV-Visible spectroscopy revealed that, the characteristic surface plasmon resonance (SPR) peak for Ag-Au bimetallic nano-alloy was detected at 480-495 nm and X-ray diffraction patterns confirmed the successive role of HEC in generation of bimetallic nanostructures. Transmission electron microscope (TEM) and zetasizer data were detected for clarifying the effect of the polymer concentration, addition sequencing of metal salts in reaction liquor, and reaction temperature on the morphological features and size distribution of the as-produced bimetallic nano-alloy. Referring to zetasizer analyses and TEM micrographs, small sized (10.7 nm) Ag-Au bimetallic nano-alloy was successfully produced by employing HEC as nano-producer. All the generated bimetallic nano-objects exhibited high stability with PdI ranged in 0.268-0.560. The mechanism for generation of nanostructures was confirmed according to FT-IR, 1HNMR and13CNMR spectra., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Manufacturing nanoparticles with controlled physicochemical properties using environment-friendly routes have potential to open new prospects for a variety of applications. Accordingly, several approaches have been established for manufacturing metal nanoparticles. Many of these approaches entail the use of hazardous chemicals and could be toxic to the environment, and cannot be used readily for biomedical applications. In the present work, we report a single step bio-friendly approach to formulate gold (Au), silver (Ag), and Au-Ag alloy nanoparticles with desired surface corona and composition using isonicotinylhydrazide (INH) as a reducing agent. INH also functioned as a stabilizing agent by enabling a surface corona around the nanoparticles. Remarkably, within a single step INH could also provide a handle in regulating the composition of Au and Ag in bimetallic systems without any additional chemical modification. The physicochemical and surface properties of the different nanoparticles thus obtained have been examined by analytical, spectroscopic and microscopic techniques. Cell cytotoxicity (release of lactate dehydrogenase), cell viability and intracellular reactive oxygen species (ROS) assays confirmed that the Au, Ag, and Au-Ag bimetallic nanoparticles prepared with INH are biocompatible. Finally, the presence of organic surface corona of INH on the nanoparticles was found to impart nanozyme activity and antimycobacterial sensitivity to the nanoparticles., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Bimetallic copper oxide-gold nanoalloys (CuO-Au nanoalloys) have been prepared and characterized using various techniques confirming their successful synthesis. The peroxidase-like activity of CuO-Au nanoalloys have been investigated and applied towards the colorimetric detection of glucose. CuO-Au nanoalloys as nanoenzymes exhibited peroxidase-like properties which occurred by generating the reactive oxygen species (ROS) due to the catalytic properties of CuO-Au nanoalloys.The generation of ROS was confirmed using radical and/or reactive oxygen species quenching properties of 1,3‑diphenylisobenzofuran (DPBF). The rate of production of ROS was higher when CuO-Au nanoalloys were present in a solution containing DPBF and H 2 O 2 (0.1092 min -1 ). The absorption peak of DPBF at 430 nm decreased confirming the generation of ROS. The CuO-Au nanoalloys were evaluated their potential use for colorimetric detection of glucose. The detection limit for glucose was obtained to be 6.75 μM. The detection of glucose took place in two steps and at different pH conditions, first glucose oxidation by glucose oxidase occurred in physiological pH (7.4) at 37 °C. The optimum conditions for the CuO-Au nanoalloys peroxidase-like activity were obtained at pH 4 and 25 °C. The chromogen, TMB (3,3',5,5'‑tetramethylbenzidine) oxidation to blue coloured product TMBDI (3,5,3',5'‑tetrabenzidinediimine) occurred with high intensity obtained after 6 min., (Copyright © 2018 Elsevier B.V. All rights reserved.)

We report the first observation of symmetry breaking-induced mode splitting in coupled gold-silver alloy nanodisk array (ANA). According to the plasmonic hybridization picture, the original localized surface plasmon resonance (LSPR) of individual nanodisk is split into a pair of high and low energy modes when placed in between a superstrate and a substrate. Although well studied in single silver nanoparticles, the high energy mode has been largely suppressed in gold nanoparticles, which nevertheless are more chemically robust and have superior environmental stability. Herein, we show that the high energy mode can be partially restored and precisely engineered to ∼540 nm for silver-rich alloy nanodisk which has excellent environmental stability. However, peak broadening and red-shifting occur due to plasmonic dephasing when the nanodisk diameter increases. We next demonstrate that a far-field coupled ANA fabricated by low-cost nanosphere lithography can fully restore the high energy mode with electric field concentration extended into the superstrate, thereby imparting greater sensitivity to local refractive index changes. The high energy mode at 540 nm is of key importance for color change detection using low-cost RGB cameras/human vision and broadband light sources (e.g., the sun). The index sensitivity of ANA is the highest among existing plasmonic arrays (particles or holes) within a similar resonance wavelength region. We demonstrate colorimetric detection of sub-nanomolar and sub-monolayer biotin-streptavidin surface binding with a smartphone camera and a white light lamp. The high performance yet low-cost fabrication and detection technology could potentially result in affordable point-of-care biosensing technologies.

The Au-Al alloy system was investigated via a combinatorial thin film sputtering method for its potential as a plasmonic material. Au x Al 1- x combinatorial libraries were cosputtered from Au and Al elemental targets and the composition, phase, and dielectric function of a ∼350 nm film was determined using energy dispersive spectroscopy (EDS), grazing incidence X-ray diffraction (GIXRD), and spectroscopic ellipsometry, respectively. The phase evolution and optical properties were analyzed after annealing various compositions under a vacuum. The phases present matched the expected phases based on the published Al-Au binary phase diagram at all compositions. Interestingly, the mixed phase Al-AuAl 2 region showed the most optical tunability, where a maximum in the real part of the dielectric function progressively shifted to higher energy for increasing gold concentration. For almost pure AuAl 2 , the imaginary component is largely reduced in the visible range and is comparable to that of pure Al in the UV region. A 20-nm-thick film with composition Au 0.74 Al 0.26 was studied using a (scanning) transmission electron microscope with an in situ laser heating system. The structures of the as-deposited and laser annealed films were determined using selected area diffraction and the bulk plasmon of AuAl 2 and Al realized with electron energy loss spectroscopy. Last, the Au-rich solid solution region was investigated as a surface enhanced Raman spectroscopy (SERS) substrate using the benezenethiol (BT) molecule. Good SERS intensity was maintained up to 30% Al addition where enhancements of 10 5 to 10 7 were still observed.

Highly sensitive, multiplexed detection of soluble cancer protein biomarkers can facilitate early cancer screening as well as enable real-time monitoring of patients' sensitivity and resistance to therapy. Current technologies for detection of soluble cancer protein biomarkers, e.g., enzyme-linked immunosorbent assay, however, suffer from limited sensitivity, as well as the requirement of expensive monoclonal antibodies, which undergo the quality variability. Herein, we propose a sensitive, cheap, and robust surface-enhanced Raman scattering technology to detect a panel of soluble cancer protein biomarkers, including soluble programmed death 1 (sPD-1), soluble programmed death-ligand 1 (sPD-L1) and soluble epithermal growth factor receptor (sEGFR), which are related to disease progression and treatment efficacy. In this assay, gold-silver alloy nanoboxes that have strong Raman signal enhancement capability were used as plasmonic nanostructures to facilitate highly sensitive detection. In addition, nanoyeast single-chain variable fragments were utilized as mAb alternatives to allow specific and stable protein capture performance. We successfully detected sPD-1, sPD-L1, and sEGFR with a limit of detection of 6.17 pg/mL, 0.68 pg/mL, and 69.86 pg/mL, respectively. We further tested the detection of these three soluble cancer protein biomarkers in human serum and achieved recovery rates between 82.99% and 101.67%. We believe our novel platform that achieves sensitive, multiplexed, and specific detection of soluble cancer protein biomarkers could greatly benefit cancer treatment and improve patient outcome.

In this work, hollow nanobox metal-organic framework (HNM) nanocomposites were synthesised and utilised for the first time in a signal decreased electrochemical immunosensor for the ultrasensitive quantitative determination of lymphocyte activation gene-3 (LAG-3) protein, which is a newly discovered biomarker. With the aid of signal materials, namely, SiO 2 -tagged anti-LAG-3 antibody (SiO 2 -Ab 2 ) and the biotin-streptavidin system, the sensor can achieve signal amplification. Encapsulation of tin dioxide-functionalised reduced graphene oxide (rGO-SnO 2 ) and gold and platinum alloys (AuPt alloys) onto the surface of hollow nanobox metal-organic frameworks (MOFs) was performed to prepare rGO-SnO 2 /hollow nanobox-MOFs/AuPt alloys (rGO-SnO 2 /HNMs/AuPt) as the matrix. SiO 2 -Ab 2 , which is used as the signal-decreased label, can be utilised to enhance the distinction of the electrochemical signal after the specific recognition between antibodies and antigens, owing to its large steric hindrance property. In this sensor, this proposed sandwich immunosensor can achieve a high sensitivity, especially in the presence of low concentrations of the LAG-3 protein. Under optimal conditions, this sandwich-designed immunosensor exhibited a sensitive detection of the LAG-3 protein from concentrations of 0.01 ng mL -1 to 1 μg mL -1 , with a lower detection limit of 1.1 pg mL -1 (based on 3σ). We proposed that this ultrasensitive biosensor can be utilised for the detection of the LAG-3 protein in early clinical tumour diagnosis., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Herein, well-defined hollow dendritic AuPtAg alloyed nanocrystals (ANCs) were synthesized by a simple L-proline-mediated one-pot aqueous method. More importantly, the synthesized hollow dendritic architectures provide a suitable platform for immobilization of anti-prostate specific antigen (PSA). The resultant label-free immunosensor exhibited the improved performance for highly sensitive detection of PSA based on the enhanced catalytic currents of K 3 [Fe(CN) 6 ] as a signal probe. Impressively, the immunosensor showed the wide linear range of 0.05-50 ng mL -1 and low detection limit of 0.017 ng mL -1 under optimal conditions for the assay of PSA, couple with the improved stability, reproducibility and selectivity. It provides a promising platform for clinical research and diagnosis., (Copyright © 2018 Elsevier B.V. All rights reserved.)

The development of high-efficient technologies for cancer biomarkers detection has attracted tremendous research effort for its great clinic significance. In this work, we designed a new type of flexible and robust nanohybrid microelectrode by modifying carbon fiber with dual nanoenzyme, i.e., AuPd alloy nanoparticles (AuPd-ANPs) decorated graphene quantum dots (GQDs) assembly, and explored its practical application in electrochemical sensing system for sensitive detection of cancer biomarker hydrogen peroxide (H 2 O 2 ) in human breast cancer cells and tissue. For the preparation of dual nanoenzyme modified microelectrode, ionic liquid was used as the electrolyte for the effective electrodeposition of GQDs on carbon fiber substrate to form a close-packed assembly under a very negative potential, then the highly dense AuPd-ANPs were uniformly decorated on GQDs assembly by electrodeposition. In virtue of the structural merits and synergistic contribution of dual nanoenzyme in enhancing the electrocatalytic activity to H 2 O 2 , the resultant nanohybrid microelectrode exhibited good sensing performances for electrochemical detection of H 2 O 2 , including a high sensitivity of 371 μA cm -2 mM -1 , a wide linear range from 1.0 μM to 18.44 mM, a low detection limit of 500 nM (a signal-to-noise ratio of 3:1), as well as good selectivity and biocompatibility, which could be used for real-time tracking H 2 O 2 released from different types of human breast cells and in situ sensitive detection of H 2 O 2 in clinical breast cancer tissue., (Copyright © 2018 Elsevier B.V. All rights reserved.)

A flower-like Au/Cu alloy nanocomposite (Au/Cu NFs) was synthesized and used in an electrochemiluminescence (ECL) based method for sensitive determination of the dye Sudan I. The Au-g-C 3 N 4 nanosheets as an ECL emitter were prepared by electrostatic adsorption between gold nanoparticles and g-C 3 N 4 . They form a film on a glassy carbon electrode (GCE) and then can be connected with Sudan I antigen via gold-nitrogen bond and amidation reactions. The Au/Cu NFs combined with Sudan I antibody also via the Au-N bond and was introduced into the modified GCE by specific recognition between the antibody and the antigen. The overlap between emission spectra of the Au-g-C 3 N 4 nanosheets and absorption spectra of Au/Cu NFs enabled the appearance of ECL resonance energy transfer process. That is, when the Sudan I analyte not present, the ECL was weakened due to absorption by the gray Au/Cu NFs on applying voltages from -1.7 V to 0 V. Conversely, the Au/Cu NFs on the GCE are reduced due to the competition for the antibody between the analyte and the antigen. A strong green ECL emission was obtained. The ECL response is linear in the 0.5 pg mL -1 to 100 ng mL -1 Sudan I concentration range, and the detection limit is 0.17 pg mL -1 . Graphical abstract An Au/Cu alloy flower-like nanocomposite (Au/Cu NFs) is firstly synthesized as an acceptor to constitute an electrochemiluminescence-resonance energy transfer (ECL-RET) system for sensitive measurement of Sudan I, while Au nanoparticles (Au NPs) functionalized graphitic carbon nitride (g-C 3 N 4 ) acted as a donor.

A novel ratiometric surface-enhanced Raman scattering (SERS) nanosensor has been developed to probe the activity of endonuclease under in vitro and in living cells conditions. The optimized alloyed Au/Ag nanoparticles (NPs) were synthesized as the SERS substrate, which combined the superior properties of both pure Au and pure Ag nanoparticles: they exhibit excellent plasmonic property with high chemical stability and low cytotoxicity. They were then employed for quantitative detection of endonuclease through functionalization with single-stranded DNA (ssDNA) carrying 3-[4-(phenylethynyl)benzylthio]propanoic acid (PEB) as endonuclease-responsive SERS signaling molecule and 4-thiophenylacetylene (TPA) as the internal standard SERS signaling molecule. In the presence of endonuclease, the ssDNA was cleaved, releasing PEB molecules from the particle surface and decreasing the SERS signal at 2215 cm -1 from PEB. Since the SERS signal at 1983 cm -1 from alkynyl TPA remained the same, quantitative detection of endonuclease was achieved, based on the ratiometric peak intensity of I 1983 / I 2215 , with a detection limit as low as 0.056 unit/mL. A highly biocompatible and antijamming ratiometric SERS sensor was established by combining the alloyed Au/AgNPs with two unique alkynes molecules with Raman signals in the cellular silent region. The ratiometric sensor was successfully employed to detect intracellular endonuclease activity as well as endonuclease in living cells for the first time.

Large-scale assembly of individual atoms over smooth surfaces is difficult to achieve. A configuration of an atom reservoir, in which individual atoms can be readily extracted, may successfully address this challenge. In this work, we demonstrate that a liquid gold-silicon alloy established in classical vapor-liquid-solid growth can deposit ordered and three-dimensional rings of isolated gold atoms over silicon nanowire sidewalls. We perform ab initio molecular dynamics simulation and unveil a surprising single atomic gold-catalyzed chemical etching of silicon. Experimental verification of this catalytic process in silicon nanowires yields dopant-dependent, massive and ordered 3D grooves with spacing down to ~5 nm. Finally, we use these grooves as self-labeled and ex situ markers to resolve several complex silicon growths, including the formation of nodes, kinks, scale-like interfaces, and curved backbones.

Purpose: When magnetic resonance imaging (MRI) is performed on patients carrying metallic implants, artifacts can disturb the images around the implants, often making it difficult to interpret them appropriately. However, metallic materials are and will be indispensable as raw materials for medical devices because of their electric conductivity, visibility under X-ray fluoroscopy, and other favorable features. What is now desired is to develop a metallic material which causes no artifacts during MRI., Materials and Methods: In the present study, we prepared a single-phase and homogeneous Au-Pt alloys (Au; diamagnetic metal, and Pt; paramagnetic metal) by the processing of thermal treatment. Volume magnetic susceptibility was measured with a SQUID Flux Meter and MRI artifact was evaluated using a 1.5-T scanner., Results: After final thermal treatment, an entirely recrystallized homogeneous organization was noted. The Au-35Pt alloy was shown to have a volume magnetic susceptibility of -8.8ppm, causing almost free from artifacts during MRI., Conclusions: We thus prepared an Au-35Pt alloy which had a magnetic susceptibility very close to that of living tissue and caused much fewer artifacts during MRI. It is promising as a material for spinal cages, intracranial electrodes, cerebral aneurysm embolization coils, markers for MRI and so on., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Novel and sensitive sandwich-type electrochemiluminescence (ECL) immunosensor was fabricated for insulin detection. Au-ZnCd 14 S combined nitrogen doping mesoporous carbons (Au-ZnCd 14 S/NH 2 -NMCs) acted as sensing platform and Au-Cu alloy nanocrystals were employed as labels to quench the ECL of Au-ZnCd 14 S/NH 2 -NMCs. Zinc-doping promoted the ECL behavior of CdS nanocrystals, with the best ECL emission obtained when the molar ratio of Zn/Cd was 1:14. Simultaneously, the modification of gold nanoparticles (Au NPs) and combination with NH 2 -NMC further enhanced the ECL emission of ZnCd 14 S due to its excellent conductivity and large specific surface area, which is desirable for the immunosensor construction. Au-Cu alloy nanocrystals were employed in the ECL system of ZnCd 14 S/K 2 S 2 O 8 triggering ECL quenching effects. The ECL spectra of ZnCd 14 S, acting as the energy donor, exhibited well overlaps with the absorption band of Au-Cu alloy nanocrystals which acted as the energy acceptor, leading to an effective ECL resonance energy transfer (ECL-RET). On the basis of the ECL quenching effects, a sensitive ECL immunosensor for insulin detection was successfully constructed with a linear response range of insulin concentration from 0.1pg/mL to 30ng/mL and the limit of detection was calculated to be 0.03pg/mL (S/N = 3)., (Copyright © 2017 Elsevier B.V. All rights reserved.)

A high quality graphene-encapsulated AuAg alloy (AuAg-GR) nanohybrid with homogeneous structure and good reproducibility over a desired area was successfully fabricated. Taking benefits of the unique architecture, such nanohybrid was employed as an efficient electrocatalyst for sensing application. The AuAg-GR based sensor could sensitively detected neurotransmitter serotonin (5-HT) with wide linear detection range (2.7nM to 4.82μM), very low detection limit (1.6nM), negligible interference, and excellent reproducibility. In addition, AuAg-GR based sensor accurately determined 5-HT in human serum samples. This is due to the enhanced catalytic activity of GR nanosheets-encapsulated AuAg nanostructures, which possessed well monodispersion of AuAg alloy, greater electrochemical active sites, and good charge transfer possibility. The obtained results imply that such nanohybrid is a potential candidate for synthesizing electrochemical sensors in requirement of high sensitivity, long-term stability, and good reproducibility., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The current report provides a simple, green and inexpensive route for one-pot fabrication of AgNPs, AuNPs, and Ag-Au nano-alloy individually onto cellulosic solid support. Cellulosic solid support was naturally extracted from plant and then was used for deposition of nanoparticles. The manufacturing was carried out through redox reaction between metal ions and alcoholic groups of cellulose, resulting in production of metallic/bimetallic nanostructures. AuNPs was obtained in size of 26.1nm smaller than AgNPs (36.3nm). Controlling in size of bimetallic nanostructures was achieved by tuning the concentrations, mass ratios of nanometal precursors and their addition sequencing in reaction liquor. Immobilization of nanoparticles/bimetallic nanostructures was frequently speeded up the reduction reaction of p-nitro-aniline, however, bimetallic nanostructures exhibited much better catalytic reactivity, where, 87.2% from p-nitro-aniline was reduced to p-phenylene-di-amine only in 20min in the presence of Ag-Au bimetallic nano-alloy., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Herein, a single-step co-reduction aqueous route was designed for preparation of hierarchical AuPt alloy nanochains, firstly using amprolium hydrochloride as a new stabilizing agent and structure-director. The morphology, structure, composition, and size of the products were characterized by a series of technique. The growth mechanism of AuPt nanochains was discussed in details. The AuPt nanochains modified glassy carbon electrode showed the improved analytical performances for determination of nitrite and hydrazine. The linear ranges of nitrite are 0.5-366.4μM and 466.4-2666.4μM for the two segments, and the detection limit is 0.03μM (S/N=3). The linear ranges of hydrazine are 5.0-116.4μM and 166.4-2666.4μM for the two segments, along with the low detection limit of 0.26μM (S/N=3). The performances of AuPt nanochains were superior to those of individual Pt and Au nanoparticles. It is ascribed to the specific hierarchical structures and synergistic effects of the bimetals., (Copyright © 2017. Published by Elsevier B.V.)

A novel hierarchical nanoporous thin film of AuPt alloy embedded in graphene (AuPt@GR) was successfully synthesized through the self-assembly of ultrafine AuPt nanoparticles (~3nm) within GR sheets by means of a facile chemical vapor deposition (CVD) procedure without the use of any external organic capping agent and reducing agent. A binder-free sensor based on the AuPt@GR hybrid material was fabricated and its electrocatalytic activity was evaluated by using it to determine epinephrine (EP) in PBS solution (pH=7.4) and in human serum spiked PBS solution. Amperometric measurements of the sensor response showed an extremely low limit of detection (0.9nM at a signal-to-noise ratio of 3), high sensitivity (1628µAmM -1 cm -2 ), wide linear detection range (1.5×10 -9 -9.6×10 -6 M), and negligible response to interferents. At the same time, the sensor also exhibited very long-term amperometric stability (4000s), cyclic voltammetric stability (500 cycles), good reproducibility, and highly accurate detection of EP in real samples. The excellent electrochemical performance was attributed to synergistic effects of Au, Pt, and GR as well as to the formation of a unique nanoporous structure that provided enhanced electrocatalytic activity, a highly electroactive surface, and fast mass transport. These results suggest strong potential of the AuPt@GR hybrids for use in biosensors and bioelectronic devices., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Cyanide is extremely toxic to organisms but difficult to detect in living biological specimens. Here, we report a new CN - sensing platform based on unmodified Au-Ag alloy nanoboxes that etch in the presence of this analyte, yielding a shift in plasmon frequency that correlates with the analyte concentration. Significantly, when combined with dark field microscopy, these particle probes can be used to measure CN - concentrations in HeLa cells and in vivo in Zebra fish embryos. The limit of detection (LOD) of the novel method is 1 nM (below the acceptable limit defined by the World Health Organization), and finite-difference time-domain (FDTD) calculations are used to understand the CN - induced spectral shifts.

One of potential applications of nano- and microscale polymer fibers is SERS-active platforms for the detection of biological compounds and microorganisms. This paper demonstrates the polymer mat obtained with Forcespinning™ technique used to detect the bacteria from blood plasma. Forcespinning™ is a new method of manufacturing of polymer fibers which can be applied to variety of polymer materials, e.g. polyethylene, nylon, PA6 and others. The method is based on the centrifugal force to draw fiber from molten polymer, which allows tuning the diameter of the fiber from tens of nanometers up to micrometers. Wide range of diameters makes the forcespun polymer mat an excellent material to filter bacteria from fluids (e.g. blood plasma, water). Covering the mat with Au:Ag alloy turns it into a SERS platform able to immobilize, detect, and identify bacteria. We provide proof-of-concept, showing detection of S. aureus, P. aeruginosa, and S. Typhimurium from blood plasma., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Fluorescent CS/Ag-Au (chitosan/silver-gold) nanocomposite containing different weight percentage of Ag and Au was synthesized using the chemical reduction method. 5-Fluorouracil (5-FU) encapsulated nanocomposite was also synthesized and its cytotoxicity towards breast cancer cell lines (MCF-7) studied. The XRD pattern of the nanocomposite shows peaks of chitosan, silver and gold. The peaks corresponding to gold and silver indicate the face centered cubic structure of silver and gold nanoparticles. The polymer matrix nanocomposite structure with chitosan as the matrix and silver-gold as the filler phase is evident from the high resolution transmission electron microscopy (HRTEM) images and an increase in particle size from∼5nm to about 12nm is noticeable on encapsulation of 5-Fluorouracil (5-FU). The presence of fluorine in the case of 5-FU encapsulated nanocomposite and the presence of reflections corresponding to 5-FU in the SAED pattern confirms the encapsulation of 5-FU into the nanocomposite, which is also confirmed by elemental mapping. The presence of a single surface plasmon resonance (SPR) peak in the case of the nanocomposite in a position in between the SPR bands of pure silver and gold nanoparticles confirms the formation of Ag-Au alloy and the elemental mapping results obtained for the nanocomposite also supports the UV-vis results. The photoluminescence (PL) spectrum clearly shows an emission peak in the near infrared region (700-900nm), which makes the nanocomposite suitable for use in cellular imaging. The application of the nanocomposite as a colorimetric sensor was also studied and it was found to be useful for the specific detection of mercury (Hg) without much interference and the detection limit was found to be 5.0×10 -8 M., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Bimetallic particles based on gold and iron have been gathering increasing interest in biomedical applications because of the synergic combination of the plasmonic features of the inert gold component with the magnetic properties of the iron or iron oxide fraction, that makes these hybrid nanomaterials suitable for imaging, therapeutic and analytical applications. In this minireview, we emphasize gold-based nanomaterials with potential for Magnetic Resonance Imaging, focusing on Au-Fe hybrid systems as potential T2-weighted, goldbased contrast agents., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Gold-based nanocrystals have attracted considerable attention for drug delivery and biological applications due to their distinct shapes. However, overcoming biological barriers is a hard and inevitable problem, which restricts medical applications of nanomaterials in vivo. Seeking for an efficient transportation to penetrate biological barriers is a common need. There are three barriers: blood-testis barrier, blood-placenta barrier, and blood-brain barrier. Here, we pay close attention to the blood-testis barrier. We found that the pentacle gold-copper alloy nanocrystals not only could enter GC-2 cells in vitro in a short time, but also could overcome the blood-testis barrier and enter male germ cells in vivo. Furthermore, we demonstrated that the entrance efficiency would become much higher in the development stages. The results also suggested that the pentacle gold-copper alloy nanocrystals could easier enter to germ cells in the pathological condition. This system could be a new method for theranostics in the reproductive system.

A facile and green strategy is reported here to synthesize gold (Au), silver (Ag) and gold-silver (Au-Ag) alloy nanoparticles (NPs) through bio-reduction reactions of aqueous corresponding metal precursors mediated by extracts of aerial parts of R. hypocrateriformis, which act as both reducing and stabilizing agents, under microwave irradiation. UV-vis spectrophotometer, XRD, FT-IR, FESEM/TEM, TGA and EDAX analysis were used to characterize the obtained NPs. The formation of NPs is evident from their surface plasmon resonance peak observed at λ max =∼550, 450 and 500nm for Au, Ag and Au-Ag alloy NPs respectively. XRD pattern revealed that fcc structure, while FT-IR spectra signify the presence of phytochemicals adsorbed on NPs. Such a biofunctionalized NPs were characterized by their weight loss, 30% due to thermal degradation of plant phytochemicals observed in TG analysis. The spherical shape of Au, Ag and Au-Ag alloy NPs (∼10-50nm) is observed by FE-SEM/TEM images. EDAX analysis confirms the expected elemental composition. Moreover, these NPs showed enhanced antimicrobial, antioxidant, and anticancer activities, though it is more pronounced for Au-Ag alloy NPs, which is due to the combining effect of phytochemicals, Au and Ag metals. Thus, the biosynthesized NPs could be applied as effective growth inhibitors for various biomedical applications., (Copyright © 2016 Elsevier Inc. All rights reserved.)

In an effort to develop electrocatalysts associated with effective design, testing, and fabrication, novel porous gold-palladium nanoalloy network-supported graphene (AuPd@GR) nanohybrids were successfully synthesized via electroless deposition followed by a chemical vapor deposition (CVD) method for the first time. The AuPd@GR nanohybrids were obtained as a continuous, porous, transparent, bendable, and ultrathin film with good assembly of the AuPd nanoalloy particles (<10nm) within the GR. The AuPd@GR nanohybrids exhibited excellent catalytic activity towards H2O2 detection with a wide detection range (5μM-11.5mM), high sensitivity (186.86μAmM(-1)cm(-2)), low limit of detection (1μM), fast response (3s), and long-term working stability (2500s). Furthermore, the AuPd@GR nanohybrids demonstrated outstanding durability, along with negligible interference from ascorbic acid, dopamine, uric acid, urea, potassium ions, chloride ions, and glucose. These findings open a new pathway to fabricate electrocatalysts for application in high performance electrochemical sensors and bioelectronics., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The exploration of new alloys with desirable properties has been a long-standing challenge in materials science because of the complex relationship between composition and microstructure. In this Research Article, we demonstrate a combinatorial strategy for the exploration of composition dependence of microstructure. This strategy is comprised of alloy library synthesis followed by high-throughput microstructure characterization. As an example, we synthesized a ternary Au-Cu-Si composition library containing over 1000 individual alloys using combinatorial sputtering. We subsequently melted and resolidified the entire library at controlled cooling rates. We used scanning optical microscopy and X-ray diffraction mapping to explore trends in phase formation and microstructural length scale with composition across the library. The integration of combinatorial synthesis with parallelizable analysis methods provides a efficient method for examining vast compositional ranges. The availability of microstructures from this vast composition space not only facilitates design of new alloys by controlling effects of composition on phase selection, phase sequence, length scale, and overall morphology, but also will be instrumental in understanding the complex process of microstructure formation in alloys.

Magneto-elastic materials (ME) have important advantages when applied as biosensors due to the possibility of wireless monitoring. Commercial Metglas 2826MB3™ (FeNiMoB) is widely used, however sensor stabilization is an important factor for biosensor performance. This study compared the effects of biocompatibility and degradation of the Metglas 2826MB3™ alloy, covered or not with a gold layer, when in contact with cell culture medium. Strips of amorphous Metglas 2826MB3™ were cut and coated with thin layers of Cr and Au, as verified by Rutherford Backscattering Spectroscopy (RBS). Using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES), the presence of metals in the culture medium was quantitatively determined for up to seven days after alloy exposure. Biocompatibility of fibroblast Chinese Hamster Ovary (CHO) cultures was tested and cytotoxicity parameters were investigated by indirect means of reduction of MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) at 1, 2 and 7 days. Cell death was further evaluated through in situ analysis using Acridine Orange/Ethidium Bromide (AO/EB) staining and images were processed with ImageJ software. Ions from Metglas(®) 2826MB3™ induced a degradation process in living organisms. The cytotoxicity assay showed a decrease in the percentage of live cells compared to control for the ME strip not coated with gold. AO/EB in situ staining revealed that most of the cells grown on top of the gold-covered sensor presented a normal morphology (85.46%). Covering ME sensors with a gold coating improved their effectiveness by generating protection of the transducer by reducing the release of ions and promoting a significant cell survival., (Copyright © 2016 Elsevier B.V. All rights reserved.)