Functional DNA-Zn2+ coordination nanospheres for sensitive imaging of 8-oxyguanine DNA glycosylase activity in living cells.

Sensitive monitoring of human 8-oxyguanine DNA glycosylase (hOGG1) activity in living cells is helpful to understand its function in damage repair and evaluate its role in disease diagnosis. Herein, a functional DNA-Zn2+ coordination nanospheres was proposed for sensitive imaging of hOGG1 in living cells. The nanospheres were constructed through the coordination-driven self-assembly of the entropy driven reaction (EDR) -deoxyribozyme (DNAzyme) system with Zn2+, where DNAzyme was designed to split structure and assembled into the EDR system. When the nanospheres entered the cell, the competitive coordination between phosphate in the cell and Zn2+ leaded to the disintegration of the nanospheres, releasing DNA and some Zn2+. The released Zn2+ acted as a cofactor of DNAzyme. In the presence of hOGG1, the EDR was completed, accompanied by fluorescence recovery and the generation of a complete DNAzyme. With the assistance of Zn2+, DNAzyme continuously cleaved substrates to produce plenty of fluorescence signals, thus achieving sensitive imaging of hOGG1 activity. The nanospheres successfully achieved sensitive imaging of hOGG1 in human cervical cancer cells (HeLa), human non-small cell lung cancer cells and human normal colonic epithelial cells, and assayed changes in hOGG1 activity in HeLa cells. This nanospheres may provide a new tool for intracellular hOGG1 imaging and related biomedical studies.

Naked mesoporous rhodium nanospheres with glutathione depletion and photothermal capabilities for tumor therapy.

Pancreatic and colon cancer are malignant tumors of the digestive system that currently lack effective treatments. In cancer cells, a high level of glutathione (GSH) is indispensable to scavenge excessive reactive oxygen species (ROS) and detoxify xenobiotics, which make it a potential target for cancer therapy. GSH depletion has been proved to improve the therapeutic efficacy of photodynamic therapy. Here, we reported that naked mesoporous rhodium nanospheres (Rh MNs), prepared by soft template redox method, can act as GSH depletion agent and photothermal conversion agent to achieve synergistic therapy respectively. Different from conventional nanoagents, Rh MNs with the characteristics of easy synthesis, simple structure and multiple functions can decrease the GSH level in tumor and depict excellent photothermal ability with a high photothermal conversion efficiency (PTCE) up to 39%. Notably, multiple anti-tumor mechanisms in CT26 and BxPC-3 tumor models, include inhibited anti-apoptosis, DNA replication repair, and GSH synthesis are revealed, and the pancreatic tumor cure rate of the cooperative treatment group is 80%. Collectively, we developed Rh MNs to combine GSH depletion with photothermal therapy for cancer treatment.

An enzymatic hydrolysis-based platform technology for the efficient high-yield production of cellulose nanospheres.

This study evaluates the feasibility of using enzymatic technology to produce novel nanostructures of cellulose nanomaterials, specifically cellulose nanospheres (CNS), through enzymatic hydrolysis with endoglucanase and xylanase of pre-treated cellulose fibers. A statistical experimental design facilitated a comprehensive understanding of the process parameters, which enabled high yields of up to 82.7 %, while maintaining a uniform diameter of 54 nm and slightly improved crystallinity and thermal stability. Atomic force microscopy analyses revealed a distinct CNS formation mechanism, where initial fragmentation of rod-like nanoparticles and subsequent self-assembly of shorter rod-shaped nanoparticles led to CNS formation. Additionally, adjustments in process parameters allowed precise control over the CNS diameter, ranging from 20 to 100 nm, highlighting the potential for customization in high-performance applications. Furthermore, this study demonstrates how the process framework, originally developed for cellulose nanocrystals (CNC) production, was successfully adapted and optimized for CNS production, ensuring scalability and efficiency. In conclusion, this study emphasizes the versatility and efficiency of the enzyme-based platform for producing high-quality CNS, providing valuable insights into energy consumption for large-scale economic and environmental assessments.

Reactive Oxygen Species-Scavenging Mesoporous Poly(tannic acid) Nanospheres Alleviate Acute Kidney Injury by Inhibiting Ferroptosis.

Acute kidney injury (AKI), predominantly associated with the excess production of endogenous ROS, is a serious renal dysfunction syndrome. Ferroptosis characterized by iron-dependent regulated cell death has significant involvement in AKI pathogenesis. As symptomatic treatment of AKI remains clinically limited, a new class of effective therapies has emerged, which is referred to as nanozyme. In our research, a natural mesoporous poly(tannic acid) nanosphere (referred to as PTA) was developed that can successfully mimic the activity of superoxide dismutase (SOD) by Mussel-inspired interface deposition strategy, for effective ROS scavenging and thus inhibition of ferroptosis to attenuate AKI. As anticipated, PTA mitigated oxidative stress and inhibited ferroptosis, as opposed to other modes of cell death such as pyroptosis or necrosis. Furthermore, PTA exhibited favorable biocompatibility and safeguarded the kidney against ferroptosis by enhancing the expression of SLC7a11/glutathione peroxidase 4(GPX4) and Nrf2/HO-1, while reducing the levels of ACSL4 protein in the ischemia and reperfusion injury (IRI)-induced AKI model. Moreover, PTA effectively suppressed aberrant expression of inflammatory factors. Overall, this study introduced antioxidative nanozymes in the form of mesoporous polyphenol nanospheres, showcasing exceptional therapeutic efficacy in addressing ROS-related diseases. This novel approach holds promise for clinical AKI treatment and broadens the scope of biomedical applications for nanozymes.

Nanoarchitecturing of Mo2C nanospheres on carbon cloth as an electrochemical sensing platform for determination of caffeic acid in tea samples.

In the present paper, carbon cloth (CC) as a flexible substrate was modified by molybdenum carbide nanospheres (Mo2C NSs @CC) by the drop-coating method to develop a sensitive electrochemical platform for detecting caffeic acid. The uniform Mo2C NSs were prepared via an easy route followed by pyrolyzing the precursor of the Mo-polydopamine (Mo-PDA) NSs. The Mo2C NSs were characterized and analyzed by X-ray diffraction (XRD), field emission scanning electron microscopy/energy dispersive X-ray spectroscopy (FE-SEM/EDS), Raman spectroscopy (RS), and electrochemical methods. CC not only gave a flexible feature to the sensor but also provided a larger surface area for Mo2C NSs. Meanwhile, the excellent conductivity and large electroactive specific surface area of Mo2C NSs exhibited excellent electrocatalytic performance for caffeic acid determination. The developed sensor showed high sensitivity and selectivity, good reproducibility, and long-term stability with a limit of detection (LOD) and a wide linear range of 0.001 µM (S/N = 3) and 0.01-50 µM, respectively. In addition, the Mo2C NSs @CC sensor showed a promising application prospect for the detection of caffeic acid in green and black tea samples, indicating its importance in food safety and the food industry.

Nanospheres for curcumin delivery as a precision nanomedicine in cancer therapy.

Cancer is ranked among the top causes of mortality throughout the world. Conventional therapies are associated with toxicity and undesirable side effects, rendering them unsuitable for prolonged use. Additionally, there is a high occurrence of resistance to anticancer drugs and recurrence in certain circumstances. Hence, it is essential to discover potent anticancer drugs that exhibit specificity and minimal unwanted effects. Curcumin, a polyphenol derivative, is present in the turmeric plant (Curcuma longa L.) and has chemopreventive, anticancer, radio-, and chemo-sensitizing activities. Curcumin exerts its anti-tumor effects on cancer cells by modulating the disrupted cell cycle through p53-dependent, p53-independent, and cyclin-dependent mechanisms. This review provides a summary of the formulations of curcumin based on nanospheres, since there is increasing interest in its medicinal usage for treating malignancies and tumors. Nanospheres are composed of a dense polymeric matrix, and have a size ranging from 10 to 200 nm. Lactic acid polymers, glycolic acid polymers, or mixtures of them, together with poly (methyl methacrylate), are primarily used as matrices in nanospheres. Nanospheres are suitable for local, oral, and systemic delivery due to their minuscule particle size. The majority of nanospheres are created using polymers that are both biocompatible and biodegradable. Previous investigations have shown that the use of a nanosphere delivery method can enhance tumor targeting, therapeutic efficacy, and biocompatibility of different anticancer agents. Moreover, these nanospheres can be easily taken up by mammalian cells. This review discusses the many curcumin nanosphere formulations used in cancer treatment.

Mie Resonant Metal Oxide Nanospheres for Broadband Photocatalytic Enhancements.

Metal oxides are widely used in heterogeneous catalysis as supports to disperse catalytically active nanoparticles, isolated atomic sites, or even as catalysts themselves. Herein, we present a method to produce optically active metal oxide supports that exhibit size-dependent Mie resonances based on TiO2 nanospheres with tunable size, crystalline phase composition, and optical properties. Mie resonant TiO2 nanospheres were used as supports to disperse Au, Pt, and Pd nanoparticles. We have found up to a 50-fold enhancement of the electric field at the metal oxide/metal interface corresponding to wavelength-dependent multipolar resonances in the TiO2 structure. Using Au/TiO2 as a prototypical photocatalyst, we demonstrate broadband rate enhancements between 400 and 800 nm during CO oxidation, with a noticeable increase below 500 nm. This increased reactivity at higher photon energies is due to improved photon utilization and interband absorption in the gold that results in greater secondary electron generation through electron-electron scattering processes, thus leading to higher rates in conjunction with the Mie scattering TiO2 support. This study not only highlights the potential of Mie resonant TiO2 in broadband photocatalytic enhancements but also for developing various Mie resonant metal oxide supports, such as ZnO or Cu2O, which can improve photocatalytic performance for a number of critical reactions. As the chemical and energy industries move toward conversion technologies driven by renewable energy sources, the strategy of designing optical resonances into oxide supports that are already widely used could enable a straightforward adaptation of photochemical processing based on traditional heterogeneous catalysts.

Formation of Olive-like TiO2 Nanospheres in a Polymeric Mesh by Sol-Gel Method.

Olive-like TiO2 (titanium dioxide), nanospheres compounds were synthesized. Polysaccharide (1-3 linked ß-D galactapyranose and 1.4-linked 3.6 anyhdro-α-L-galactopyranose and titanium isopropoxide (IV) was used as a precursor in its formation. The powder sample was evaluated by scanning tunneling microscope, X-ray diffraction pattern, power spectral density, fast Fourier transform, differential thermal analysis, continuous wavelet transform, and isotropy texture analysis. The results demonstrate that these nanospheres can successfully be synthesized in a solution using a polysaccharide network by means of the sol-gel method. The synthesized olive-like TiO2 nanospheres have diameters ranging from 50 nm to 500 nm. The synthesis parameters, such as temperature, time, and concentration of the polysaccharide, were controlled in solution.

Interfacial Membranization of Regenerated Cellulose Nanoparticles and a Protein Renders Stable Water-in-Water Emulsion.

Pickering water-in-water (W/W) emulsions stabilized by biobased colloids are pertinent to engineering biomaterials with hierarchical and confined architectures. In this study, stable W/W emulsions are developed through membranization utilizing biopolymer structures formed by the adsorption of cellulose II nanospheres and a globular protein, bovine serum albumin (BSA), at droplet surfaces. The produced cellulose II nanospheres (NPcat, 63 nm diameter) bearing a soft and highly accessible shell, endow rapid and significant binding (16 mg cm- 2) with BSA. NPcat and BSA formed complexes that spontaneously stabilized liquid droplets, resulting in stable W/W emulsions. It is proposed that such a system is a versatile all-aqueous platform for encapsulation, (bio)catalysis, delivery, and synthetic cell mimetics.

Tailored Design of Mesoporous Nanospheres with High Entropic Alloy Sites for Efficient Redox Electrocatalysis.

High Entropy Alloys (HEAs) are a versatile material with unique properties, tailored for various applications. They enable pH-sensitive electrocatalytic transformations like hydrogen evolution reaction (HER) and hydrogen oxidation reactions (HOR) in alkaline media. Mesoporous nanostructures with high surface area are preferred for these electrochemical reactions, but designing mesoporous HEA sis challenging. To overcome this challenge, a low-temperature triblock copolymer-assisted wet-chemical approach is developed to produce mesoporous HEA nanospheres composed of PtPdRuMoNi systems with sufficient entropic mixing. Owing to active sites with inherent entropic effect, mesoporous features, and increased accessibility, optimized HEA nanospheres promote strong HER/HOR performance in alkaline medium. At 30 mV nominal overpotential, it exhibits a mass activity of ≈167 (HER) and 151 A gPt -1 (HOR), far exceeding commercial Pt-C electrocatalysts (34 and 48 A gPt -1) and many recently reported various alloys. The Mott-Schottky analysis reveals HEA nanospheres inherit high charge carrier density, positive flat band potential, and smaller charge transfer barrier, resulting in better activity and faster kinetics. This micelle-assisted synthetic enable the exploration of the compositional and configurational spaces of HEAs at relatively low temperature, while simultaneously facilitating the introduction of mesoporous nanostructures for a wide range of catalytic applications.

Potent anti-inflammatory and anti-apoptotic activities of electrostatically complexed C-peptide nanospheres ameliorate diabetic nephropathy.

In the present era of "Diabetic Pandemic", peptide-based therapies have generated immense interest however, are facing odds due to inevitable limitations like stability, delivery complications and off-target effects. One such promising molecule is C-peptide (CPep, 31 amino acid polypeptide with t1/2 30 min); it is a cleaved subunit of pro-insulin, well known to suppress microvascular complications in kidney but has not been able to undergo translation to the clinic till date. Herein, a polymeric CPep nano-complexes (NPX) was prepared by leveraging electrostatic interaction between in-house synthesized cationic, polyethylene carbonate (PEC) based copolymer (Mol. wt. 44,767 Da) and negatively charged CPep (Mol. wt. 3299 Da) at pH 7.4 and further evaluated in vitro and in vivo. NPX exhibited a spherical morphology with a particle size of 167 nm and zeta potential equivalent to +10.3, with 85.70 % of CPep complexation efficiency. The cellular uptake of FITC-tagged CPep NPX was 95.61 % in normal rat kidney cells, NRK-52E. Additionally, the hemocompatible NPX showed prominent cell-proliferative, anti-oxidative (1.8 folds increased GSH; 2.8 folds reduced nitrite concentration) and anti-inflammatory activity in metabolic stress induced NRK-52E cells as well. The observation was further confirmed by upregulation of anti-apoptotic protein BCl2 by 3.5 folds, and proliferative markers (ß1-integrin and EGFR) by 3.5 and 2.3 folds, respectively, compared to the high glucose treated control group. Pharmacokinetic study of NPX in Wistar rats revealed a 6.34 folds greater half-life than free CPep. In in-vivo efficacy study in STZ-induced diabetic nephropathy animal model, NPX reduced blood glucose levels and IL-6 levels significantly by 1.3 and 2.5 folds, respectively, as compared to the disease control group. The above findings suggested that NPX has tremendous potential to impart sustained release of CPep, resulting in enhanced efficacy to treat diabetes-induced nephropathy and significantly improved renal pathology.

Sub-femtomolar vertical graphene field effect immunosensor for detection of lung tumor markers.

Lung cancer is the main cancer that endangers human life worldwide, with the highest mortality rate. The detection of lung tumor markers is of great significance for the early diagnosis and subsequent treatment of lung cancer. In this study, a vertical graphene field effect transistor (VGFET) immunosensor based on graphene/C60 heterojunction was created to offer quantitative detections for the lung tumor markers carcinoembryonic antigen (CEA), cytokeratin 19 fragment (Cyfra21-1), and neuron-specific enolase (NSE). The experimental results showed that the sensitive range for standard antigen is between 1 pg/ml to 100 ng/ml, with a limit of detection (LOD) of 5.6 amol/ml for CEA, 33.3 amol/ml for Cyfra 21-1 and 12.8 amol/ml for NSE (1 pg/ml for all). The detection accuracy for these tumor markers was compared with the clinically used method for clinical patients on serum samples. Results are highly consistent with clinically used immunoassay in its efficient diagnosis concentration range. Subsequently, the mesoporous silica nanospheres (MSNs) with an average size of 90 nm were surface modified with glutaraldehyde, and a second antibody was assembled on MSNs, which fixes nanospheres on the antigen and amplified the field effect. The LODs for three markers are 100 fg/ml (0.56 amol/ml for CEA) under optimal circumstances of detection. This result indicates that specific binding to MSNs enhances local field effects and can achieve higher sensing efficiency for tumor marker detection at extremely low concentrations, providing effective assistance for the early diagnosis of lung cancer.

Zwitterionic nanospheres engineered co-polymer composite membrane for precise protein-protein separation via dynamic self-assembly micelle deposition.

The accurate protein-protein separation is important but technically challenging. Achieving such a precise separation using membrane requires the selective channels with appropriate pore geometry structure and high anti-fouling property. In this study, polyethersulfone-b-poly(sulfobetaine methyl methacrylate) (PES-b-PSBMA) was synthesized and engineered onto polysulfone (PSF) ultrafiltration (UF) membrane to fabricate zwitterionic nanospheres engineered co-polymer (ZN-e-CoP) composite membrane via dynamic self-assembly micelle deposition. On the one hand, self-assembly zwitterionic nanospheres were used as blocks to construct hydrophilic layers with size-dependent sieving channels, endowing ZN-e-CoP composite membranes with enhanced permselectivity and protein-protein separation abilities, meanwhile zwitterionic groups from nanospheres reinforced the structure stability of nanospheres/nanospheres and nanospheres/membrane via multiple intermolecular interactions. On the other hand, zwitterionic nanospheres can induce to produce the hydration layer enveloping themselves by binding water molecules, where hydration layer acts as a protective barrier on the membrane surface, impeding the protein adhesion. Hence, ZN-e-CoP_1a composite membrane exhibited superior separation properties with Lysozyme/Bovine Serum Albumin (BSA) separation factor of 18.1 and 95.4 % rejection against BSA, 10.1 and 2.3 times, respectively, higher these of pristine PSF membrane (1.8 and 42.1 %), without obviously sacrificing water flux. Simultaneously, hydration layer enables the ZN-e-CoP_1a membrane with enhanced anti-fouling performance and durability during the long-term operations. The proposed approach opens new pathways to fabricate excellent anti-fouling membranes for precise protein-protein separation.

Multi-functional nanozyme-based colorimetric, fluorescence dual-mode assay for Salmonella typhimurium detection in milk.

Rapid and high-sensitive Salmonella detection in milk is important for preventing foodborne disease eruption. To overcome the influence of the complex ingredients in milk on the sensitive detection of Salmonella, a dual-signal reporter red fluorescence nanosphere (RNs)-Pt was designed by combining RNs and Pt nanoparticles. After being equipped with antibodies, the immune RNs-Pt (IRNs-Pt) provide an ultra-strong fluorescence signal when excited by UV light. With the assistance of the H2O2/TMB system, a visible color change appeared that was attributed to the strong peroxidase-like catalytic activity derived from Pt nanoparticles. The IRNs-Pt in conjunction with immune magnetic beads can realize that Salmonella typhimurium (S. typhi) was captured, labeled, and separated effectively from untreated reduced-fat pure milk samples. Under the optimal experimental conditions, with the assay, as low as 50 CFU S. typhi can be converted to detectable fluorescence and absorbance signals within 2 h, suggesting the feasibility of practical application of the assay. Meanwhile, dual-signal modes of quantitative detection were realized. For fluorescence signal detection (emission at 615 nm), the linear correlation between signal intensity and the concentration of S. typhi was Y = 83C-3321 (R2 = 0.9941), ranging from 103 to 105 CFU/mL, while for colorimetric detection (absorbamce at 450 nm), the relationship between signal intensity and the concentration of S. typhi was Y = 2.9logC-10.2 (R2 = 0.9875), ranging from 5 × 103 to 105 CFU/mL. For suspect food contamination by foodborne pathogens, this dual-mode signal readout assay is promising for achieving the aim of convenient preliminary screening and accurate quantification simultaneously.

Tailoring ZnS nanostructures through precipitation-cum-hydrothermal synthesis for enhanced wastewater purification and antibacterial treatment.

This study presents a novel blend of synthesis techniques for shape-controlled ZnS nanoparticles. Zinc sulfide (ZnS) nanoparticles with distinct morphologies cauliflower-like microstructures (∼4.5 µm) and uniform nanospheres (200-700 nm) were synthesized through an innovative blend of precipitation and hydrothermal techniques. Capping with polyvinylpyrrolidone (PVP) significantly decreased crystallite size (3.93 nm-2.36 nm), modulated the band gap (3.57 eV-3.71 eV), and dramatically influenced morphology, highlighting the novelty of shape-controlled synthesis and its impact on optoelectronic and functional properties. X-ray diffraction confirmed crystallinity and revealed the size-controlling influence of PVP. UV-vis spectroscopy suggested potential tuning of optical properties due to band gap widening upon PVP capping. Field-emission scanning electron microscopy (FESEM) unveiled distinct morphologies: cauliflower-like microstructures for ZnS and uniform nanospheres (200-700 nm) for PVP-ZnS. Both structures were composed of smaller spherical nanoparticles, demonstrating the role of PVP in promoting controlled growth and preventing agglomeration. High-resolution transmission electron microscope (HRTEM) images depicted that the majority of nanoparticles maintain a spherical shape, though slight deviations from perfect sphericity can be discerned. Fourier-transform infrared (FTIR) spectroscopy confirmed that successful PVP encapsulation is crucial for shaping nanospheres and minimizing aggregation through steric hindrance. Photocatalytic activity evaluation using methylene blue (MB) dye degradation revealed significantly faster degradation by PVP-ZnS under ultraviolet (UV) irradiation (within 60 min as compared to 120 min for ZnS), showcasing its superior performance. This improvement can be attributed to the smaller size, higher surface area, and potentially optimized band gap of PVP-ZnS. Additionally, PVP-ZnS exhibited promising antibacterial activity against S. aureus and P. aeruginosa, with increased activity at higher nanoparticle concentrations.

Magnetic Tunability via Control of Crystallinity and Size in Polycrystalline Iron Oxide Nanoparticles.

Iron oxide nanoparticles (IONPs) are widely used for biomedical applications due to their unique magnetic properties and biocompatibility. However, the controlled synthesis of IONPs with tunable particle sizes and crystallite/grain sizes to achieve desired magnetic functionalities across single-domain and multi-domain size ranges remains an important challenge. Here, a facile synthetic method is used to produce iron oxide nanospheres (IONSs) with controllable size and crystallinity for magnetic tunability. First, highly crystalline Fe3O4 IONSs (crystallite sizes above 24 nm) having an average diameter of 50 to 400 nm are synthesized with enhanced ferrimagnetic properties. The magnetic properties of these highly crystalline IONSs are comparable to those of their nanocube counterparts, which typically possess superior magnetic properties. Second, the crystallite size can be widely tuned from 37 to 10 nm while maintaining the overall particle diameter, thereby allowing precise manipulation from the ferrimagnetic to the superparamagnetic state. In addition, demonstrations of reaction scale-up and the proposed growth mechanism of the IONSs are presented. This study highlights the pivotal role of crystal size in controlling the magnetic properties of IONSs and offers a viable means to produce IONSs with magnetic properties desirable for wider applications in sensors, electronics, energy, environmental remediation, and biomedicine.

Facile Synthesis of Ultra-Small Silver Nanoparticles Stabilized on Carbon Nanospheres for the Etherification of Silanes.

The dehydrocoupling reaction between alcohols and hydrosilanes is considered to be one of the most atom-economical ways to produce Si-O coupling compounds because its byproduct is only hydrogen (H2), which make it extremely environmentally friendly. In past decades, various kinds of homogeneous catalysts for the dehydrocoupling of alcohols and hydrosilanes, such as transition metal complexes, alkaline earth metals, alkali metals, and noble metal complexes, have been reported for their good activity and selectivity. Nevertheless, the practical applications of these catalysts still remain unsatisfactory, which is mainly restricted by environmental impact and non-reusability. A facile and recyclable heterogeneous catalyst, ultra-small Ag nanoparticles supported on porous carbon (Ag/C) for the etherification of silanes, has been developed. It has high catalytic activity for the Si-O coupling reaction, and the apparent activation energy of the reaction is about 30 kJ/mol. The ultra-small Ag nanoparticles dispersed in the catalyst through the carrier C have an enrichment effect on all reactants, which makes the reactants reach the adsorption saturation state on the surface of Ag nanoparticles, thus accelerating the coupling reaction process and verifying that the kinetics of the reaction of the catalyst indicate a zero-grade reaction.

Bimetallic PtAu-Decorated SnO2 Nanospheres Exhibiting Enhanced Gas Sensitivity for Ppb-Level Acetone Detection.

Acetone is a biomarker found in the expired air of patients suffering from diabetes. Therefore, early and accurate detection of its concentration in the breath of such patients is extremely important. We prepared Tin(IV) oxide (SnO2) nanospheres via hydrothermal treatment and then decorated them with bimetallic PtAu nanoparticles (NPs) employing the approach of in situ reduction. The topology, elemental composition, as well as crystal structure of the prepared materials were studied via field emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. The findings revealed that bimetallic PtAu-decorated SnO2 nanospheres (PtAu/SnO2) were effectively synthesized as well as PtAu NPs evenly deposited onto the surface of the SnO2 nanospheres. Pure SnO2 nanospheres and PtAu/SnO2 sensors were prepared, and their acetone gas sensitivity was explored. The findings demonstrated that in comparison to pristine SnO2 nanosphere sensors, the sensors based on PtAu/SnO2 displayed superior sensitivity to acetone of 0.166-100 ppm at 300 °C, providing a low theoretical limit of detection equal to 158 ppm. Moreover, the PtAu/SnO2 sensors showed excellent gas response (Ra/Rg = 492.3 to 100 ppm), along with fast response and recovery (14 s/13 s to 10 ppm), good linearity of correlation, excellent repeatability, long-term stability, and satisfactory selectivity at 300 °C. This improved gas sensitivity was because of the electron sensitization of the Pt NPs, the chemical sensitization of the Au NPs, as well as the synergistic effects of bimetallic PtAu. The PtAu/SnO2 sensors have considerable potential for the early diagnosis and screening of diabetes.

Bioinspired Core-shell nanospheres integrated in multi-signal immunochromatographic sensor for high throughput sensitive detection of Bongkrekic acid in food.

Nowadays, notable progress has been achieved in detecting foodborne toxins by employing nanoenzyme-based lateral flow immunoassay (NLFIA) sensors in point-of-care testing (POCT). It continues to be a major challenge to maximize the enzyme-like performance of nanozymes for educe any potential uncertainties in catalytic process. In this study, we employed a facile and efficient self-assembly approach to fabricate nucleoid-shell structured biomimetic nanospheres CuS@Au-Pt (CAP), which demonstrates enhanced brightness of the colorimetric signal, excellent affinity, and excellent peroxidase activity. The integration of CAP with a competitive-assay NLFIA platform enabled sensitive immunochromatographic detection of bongkrekic acid (BA), with LOD as low as 0.66 ng/mL. After signal amplification through enzyme-like reaction, the detection range was extended around 1-fold. Additionally, CAP-NLFIA effectively detected BA with a recovery rate of 80.96-119.36% for real samples. The study proposes using CAP as a signal reporter in a dual-readout LFIA, which can establish a high throughput sensitive detection platform.

Superparamagnetic photonic crystals with DNA probes for rapid visual detection of mercury.

A novel superparamagnetic photonic crystal DNA probe (Fe3O4@SiO2@amino@DNA SPC) was developed to enable rapid visual detection of Hg2+. This unique photonic crystal (PC) was synthesized by combining superparamagnetic nanospheres with DNA probes. The DNA probe, rich in thymine (T), detects mercury ions through base mismatch, resulting in the formation of T-Hg2+-T loop hairpin structures. With the binding of Hg2+ to the probe attached to superparamagnetic nanospheres, the PC structure assembled by these nanospheres, formed by the magnetic field, was changed. This change enhanced the reflection intensity; it could be quantified using a fiber optic spectrometer and was visible to the naked eye. The Fe3O4@SiO2@amino@DNA SPC, specific to Hg2+, exhibited a reflection peak at 679 nm, which intensified with increasing Hg2+ concentration. The reflection intensity increased by 132.58 a.u., and the PC color shifted from red to yellow as the Hg2+ concentration increased from 0.1 µg/L to 1 mg/L.