Formation of partially embedded Au nanostructures: Ion beam irradiation on thin film.

The Au partially embedded nanostructure (PEN) is synthesized by ion irradiation on an Au thin film deposited on a glass substrate using a 50 keV Ar ion. Scanning electron microscopy results show ion beam-induced restructuring from irregularly shaped nanostructures (NSs) to spherical Au NSs, and further ion irradiation leads to the formation of well-separated spherical nanoparticles. Higuchi's algorithm of surface analysis is utilized to find the evolution of surface morphology with ion irradiation in terms of the Hurst exponent and fractal dimension. The Au PEN is evidenced by Rutherford backscattering spectrometry and optical studies. Also, the depth of the mechanism behind synthesized PEN is explained on the basis of theoretical simulations, namely, a unified thermal spike and a Monte Carlo simulation consisting of dynamic compositional changes (TRIDYN). Another set of plasmonic NSs was formed on the surface by thermal annealing of the Au film on the substrate. Glucose sensing has been studied on the two types of plasmonic layers: nanoparticles on the surface and PEN. The results reveal the sensing responses of both types of plasmonic layers. However, PEN retains its plasmonic behavior as the NSs are still present after washing with water, which demonstrates the potential for reusability. RESEARCH HIGHLIGHTS: Synthesis of PENs by ion irradiation Utilization of Higuchi's algorithm to explore the surface morphology. Unified thermal spike and TRIDYN simulations being used to explain the results. Glucose is only used as a test case for reusability of substrate.

Co-Application of Silver Nanoparticles and Symbiotic Fungus Piriformospora indica Improves Secondary Metabolite Production in Black Rice.

In the current research, unique Nano-Embedded Fungus (NEF), made by the synergic association of silver nanoparticles (AgNPs) and endophytic fungus (Piriformospora indica), is studied, and the impact of NEF on black rice secondary metabolites is reported. AgNPs were synthesized by chemical reduction process using the temperature-dependent method and characterized for morphological and structural features through UV visible absorption spectroscopy, zeta potential, XRD, SEM-EDX, and FTIR spectroscopy. The NEF, prepared by optimizing the AgNPs concentration (300 ppm) in agar and broth media, showed better fungal biomass, colony diameter, spore count, and spore size than the control P. indica. Treatment with AgNPs, P. indica, and NEF resulted in growth enhancement in black rice. NEF and AgNPs stimulated the production of secondary metabolites in its leaves. The concentrations of chlorophyll, carotenoids, flavonoids, and terpenoids were increased in plants inoculated with P. indica and AgNPs. The findings of the study highlight the synergistic effect of AgNPs and the fungal symbionts in augmenting the secondary metabolites in leaves of black rice.

Environmental friendly Polyacrylonitrile nanofiber mats encapsulated and coated with green algae mediated Titanium oxide nanoparticles for efficient oil spill adsorption.

Oil spill causes extreme environmental damage, from aquatic life to seabirds, disrupting the entire ecosystem. Herein, we have synthesized high scale, economical and bio-compatible, green algae mediated Titanium oxide (TiO2) nanoparticles and Polyacrylonitrile (PAN) nanofiber mats. We have studied the effect of encapsulation and coating of TiO2 nanoparticles over nanofiber mats for highly efficient oil spill adsorption. TiO2 encapsulated and coated PAN (TECP) nanofibers showed a maximum of 62.34 g g-1 adsorption capacity of petroleum oil from the water surface. Moreover, the composite mats show maximum adsorption within 45 s for up to 5 repeated cycles. Further, it has been observed that the adsorption capacity has increased by increasing the weight of the composite nanofiber mats, which confirms its commercial applicability. Thus, this work provides rapid, large-scale, economical, bio-compatible, and highly effective adsorbents for oil spill cleaning and extraction over natural waterbodies.

Rapid and label-free detection of Aflatoxin-B1viamicrofluidic electrochemical biosensor based on manganese (III) oxide (Mn3O4) synthesized by co-precipitation route at room temperature.

Aflatoxin B1 (AFB1) is the most toxic mycotoxin, naturally occurring in food items, and it causes several types of lethal diseases. Therefore, a rapid and convenient detection method for AFB1 is the first step toward overcoming the effect of AFB1. The current work presents the development of an efficient microfluidic electrochemical-based biosensor using tri-manganese tetroxide nanoparticles (Mn3O4nps) for AFB1 detection. The Mn3O4nps were synthesized at room temperature through the co-precipitation route. Its phase purity, structural and morphological studies have been characterized through x-ray diffraction, Raman spectroscopy, energy-dispersive x-ray, Fourier transform infrared spectroscopy and transmission electron microscopy. The mask-less UV-lithography was carried out to fabricate the three-electrode chip and microfluidic channel of the microfluidic electrochemical biosensing system. The designed microfluidic immunosensor (BSA/Ab-AFB1/Mn3O4/ITO) was fabricated using the three-electrode chip, microfluidic channel in poly-dimethyl siloxane. The fabricated sensor exhibited the 3.4µA ml ng-1cm-2sensitivity and had the lowest lower detection limit of 0.295 pg ml-1with the detection range of 1 pg ml-1to 300 ng ml-1. Additionally, the spiked study was also performed with this immunoelectrode and a recovery rate was obtained of 108.2%.

Simple and facile carbon dots based electrochemical biosensor for TNF-α targeting in cancer patient's sample.

Tumour Necrosis Factor (TNF-α) is a pro-inflammatory cytokine having key roles in cell death, differentiation, survival, proliferation, migration and is a modulator of immune system. Therefore, TNF-α is an ideal biomarker for several disease diagnosis including cancer. However, out of all the biomarkers of cancer, TNF-α) is less explored for cancer detection. Only a few reports are available of developing biosensors for TNF-α targeting in human serum samples. Also, Carbon Dots (CDs) remains less explored in biosensor application. In this regard, for the first time, a sensitive and low-cost electrochemical biosensor based on CDs has developed. CDs were synthesized by simple yet facile microwave pyrolysis. Poly methyl methacrylate (PMMA) was selected as the matrix to hold CDs to fabricate the biosensing platform. This novel CD-PMMA nanocomposite featuring excellent biocompatibility, exceptional electrocatalytic conductivity, and large surface area. CD-PMMA was applied as transducing material to efficiently conjugate antibodies specific towards TNF-α and fabricate electrochemical immunosensor for specific detection of TNF-α. The fabricated immunosensor was used for the detection of TNF-α within a wide dynamic range of 0.05-160 pg mL-1 with a lower detection limit of 0.05 pg mL-1 and sensitivity of 5.56 pg mL-1 cm-2. Furthermore, this CDs based immunosensor retains high sensitivity, selectivity, and stability. This immunosensor demonstrated a high correlation with the conventional technique, Enzyme-Linked Immunosorbent Assay for early screening of cancer patient serum samples.

Non-enzymatic and rapid detection of glucose on PVA-CuO thin film using ARDUINO UNO based capacitance measurement unit.

Glucose measurement is one of the essential health monitoring practices for maintaining blood sugar levels. Here, we have fabricated a highly specific capacitive nano-sensor for non-enzymatic glucose detection. Capacitance measurements were carried out on polyvinyl alcohol capped copper oxide (PVA-CuO) thin films on indium tin oxide (ITO) coated glass using ARDUINO UNO. The capacitance study shows a decrease in capacitance with an increase in glucose concentrations. The applicability in real samples was performed by studying the glucose in the presence of fetal bovine serum. Most commonly found interfering agents were used for interference studies, which confirmed the capacitive nano-sensor specificity. The system was further checked for repeatability up to six readings and reproducibility up to 5 chips. The shelf-life study showed stability for four weeks of a chip. These studies indicate that this capacitance-based measurement unit can be used for reliable, rapid, and non-enzymatic detection of glucose in real sample.

Fabrication of label-free and ultrasensitive electrochemical immunosensor based on molybdenum disulfide nanoparticles modified disposable ITO: An analytical platform for antibiotic detection in food samples.

Here, we aimed to fabricate a label-free immunosensing platform for the first time based on molybdenum disulfide nanoparticles (nMoS2NPs) deposited on ITO) coated glass substrate for the electrochemical detection of ampicillin (AMP). The stable and high surface area of nMoS2NPs were made by a low-temperature one-step hydrothermal route, bestowing the carrying capacity of anti-AMP (antibody against AMP) through an amide linkage. The spectroscopic, morphological, and structural characterization of the proposed electrodes were performed using various analytical and electrochemical techniques. The differential pulse voltammetry technique was utilized to evaluate anti-AMP and AMP interaction on the electrode surface. The developed immunosensor exhibits high sensitivity, a broad detection range having a significant detection limit towards detection of AMP having excellent selectivity, acceptable stability, and reproducibility. Furthermore, the applicability of the proposed immunosensor was tested in spiked milk, water, and orange juice, and the results confirmed the consistency of the immunosensor.

Ubiquitous organic molecule-based free-standing nanowires with ultra-high aspect ratios.

The critical dimension of semiconductor devices is approaching the single-nm regime, and a variety of practical devices of this scale are targeted for production. Planar structures of nano-devices are still the center of fabrication techniques, which limit further integration of devices into a chip. Extension into 3D space is a promising strategy for future; however, the surface interaction in 3D nanospace make it hard to integrate nanostructures with ultrahigh aspect ratios. Here we report a unique technique using high-energy charged particles to produce free-standing 1D organic nanostructures with high aspect ratios over 100 and controlled number density. Along the straight trajectory of particles penetrating the films of various sublimable organic molecules, 1D nanowires were formed with approximately 10~15 nm thickness and controlled length. An all-dry process was developed to isolate the nanowires, and planar or coaxial heterojunction structures were built into the nanowires. Electrical and structural functions of the developed standing nanowire arrays were investigated, demonstrating the potential of the present ultrathin organic nanowire systems.

Gut microbiota derived trimethylamine N-oxide (TMAO) detection through molecularly imprinted polymer based sensor.

Trimethylamine N-oxide (TMAO), a microbiota-derived metabolite has been implicated in human health and disease. Its early detection in body fluids has been presumed to be significant in understanding the pathogenesis and treatment of many diseases. Hence, the development of reliable and rapid technologies for TMAO detection may augment our understanding of pathogenesis and diagnosis of diseases that TMAO has implicated. The present work is the first report on the development of a molecularly imprinted polymer (MIP) based electrochemical sensor for sensitive and selective detection of TMAO in body fluids. The MIP developed was based on the polypyrrole (PPy), which was synthesized via chemical oxidation polymerization method, with and without the presence of TMAO. The MIP, NIP and the non-sonicated polymer (PPy-TMAO) were separately deposited electrophoretically onto the hydrolyzed indium tin oxide (ITO) coated glasses. The chemical, morphological, and electrochemical behavior of MIP, non-imprinted polymer (NIP), and PPy-TMAO were characterized using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and electrochemical techniques. The detection response was recorded using differential pulse voltammetry (DPV), which revealed a decrease in the peak current with the increase in concentration of TMAO. The MIP sensor showed a dynamic detection range of 1-15 ppm with a sensitivity of 2.47 µA mL ppm-1 cm-2. The developed sensor is easy to construct and operate and is also highly selective to detect TMAO in body fluids such as urine. The present research provides a basis for innovative strategies to develop sensors based on MIP to detect other metabolites derived from gut microbiota that are implicated in human health and diseases.

Fluorescence tuning behavior of carbon quantum dots with gold nanoparticles via novel intercalation effect of aldicarb.

A simple, sensitive and rapid fluorometric system has been developed for the detection of aldicarb (ALD) based on inner filter effect (IFE) of gold nanoparticles (AuNPs) on fluorescence (FL) intensity of carbon quantum dots (CQDs). Addition of CQDs into AuNPs, gets them aggregated due to electrostatic interaction resulting in quenching the FL intensity of CQDs. With addition of ALD into AuNPs, an intercalated layer was formed between them through Au-N and Au-S bond which reduced IFE of AuNPs. Hence, CQDs FL intensity recovered along with ALD concentration varying between 3.8 and 76 µg L-1 with lower detection limit of 3.02 µg L-1. The spiked real samples study in fruits, vegetables and soft drinks revealed that this sensing platform was repeatable and effective for real samples. The validation of proposed method indicates that the ALD sensor is promising and adaptable for everyday on spot environment and food safety monitoring.

Silver molybdate nanoparticles based immunosensor for the non-invasive detection of Interleukin-8 biomarker.

In this study, we report the silver molybdate nanoparticles (ß-Ag2MoO4 NPs) based non-invasive and sensitive electrochemical immunosensor for label-free detection of Interleukin-8 (IL-8) biomarker. The X-ray diffraction and Raman spectroscopy studies confirm the cubic spinel structures of ß-Ag2MoO4 NPs. High-resolution transmission electron microscopy study depicted average size of ß-Ag2MoO4 NPs as 27.15 nm. The cleaned indium tin oxide coated glass substrates were coated with spin-coated thin films of Ag2MoO4 NPs. These electrodes used for covalently immobilization of antibodies specific to IL-8 (Anti-IL-8) using EDC-NHS chemistry and unbound activated sites blocked by bovine serum albumin. Electrochemical response was obtained in the range of 1 fg mL-1 to 40 ng mL-1 and the sensitivity was found to be 7.03 µA ng-1mL cm-2 with LOD of 90 pg mL-1. Spiked samples prepared by human saliva were tested and found efficient detection with this immunoelectrode.

A highly sensitive label-free amperometric biosensor for norfloxacin detection based on chitosan-yttria nanocomposite.

Here, non-invasive and label-free detection of trace-level of norfloxacin (NF) in human urine samples has been reported using the electrochemical technique. Nanostructured yttrium oxide (nY2O3) was synthesized at low-temperature using a one-step hydrothermal process. These nY2O3 were characterized by various methods including XRD, FT-IR, Raman spectroscopy, and TEM. A biosensing platform based on nY2O3 modified with chitosan (CH) was fabricated for the detection of NF. The nanocomposite film (CH-Y2O3/ITO) was characterized by FE-SEM, contact angle measurements, and electrochemical techniques. Further, fluoroquinolones antibodies (anti-FQ) were used to modify the CH-Y2O3/ITO electrode via covalent interaction. Non-specific sites were blocked by bovine serum albumin (BSA), those present on the anti-FQ/CH-Y2O3/ITO electrode surface. The response study of BSA/anti-FQ/CH-Y2O3/ITO bioelectrode towards NF detection revealed a wide range (1 pM-10 µM) with a lower detection limit of 3.87 pM using differential pulse voltammetry (DPV). The sensitivity obtained is as high as 10.14 µA µM-1 cm2 with a fast response time of ~10 min. Moreover, the diagnostic performance of the fabricated sensor was evaluated to detect NF in urine spiked sample. The recovery of NF from the spiked sample was observed from 90.5 to 101.1%, with a maximum relative standard deviation of 7.04. The obtained results of the fabricated bioelectrode (BSA/anti-FQ/CH-Y2O3/ITO) was validated with ELISA. The results were found better when compared with earlier described biosensors and commercially existing ELISA in terms of sensitivity and lower detection limit.

Mesoporous polyaniline nanofiber decorated graphene micro-flowers for enzyme-less cholesterol biosensors.

In the present work, we have studied a nanocomposite of polyaniline nanofiber-graphene microflowers (PANInf-GMF), prepared by an in situ rapid mixing polymerization method. The structural and morphological studies of the nanocomposite (PANInf-GMF) were carried out by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared (FTIR) and Raman spectroscopy. The mesoporous, nanofibrous and microflower structures were observed by scanning electron microscopy. The functional groups and synergetic effects were observed by FTIR and micro-Raman measurements. The water wettability was carried out by a contact angle measurement technique and found to be super hydrophilic in nature towards water. This nanocomposite was deposited onto indium-tin-oxide coated glass substrate by a drop casting method and used for the detection of cholesterol using an electrochemical technique. The differential pulse voltammetry studies show the appreciable increase in the current with the addition of 1.93 to 464.04 mg dl(-1) cholesterol concentration. It is also found that the electrodes were highly selective towards cholesterol when compared to other biological interfering analytes, such as glucose, urea, citric acid, cysteine and ascorbic acid. The sensitivity of the sensor is estimated as 0.101 µA mg(-1) dl cm(-2) and the lower detection limit as 1.93 mg dl(-1). This work will throw light on the preparation of non-enzymatic biosensors based on PANInf-carbon nanostructure composites.

Formation of nanowires via single particle-triggered linear polymerization of solid-state aromatic molecules.

Nanowires occupy a prestigious place in nanoelectronics, nanomechanics, and biomimetics. Although there are notable methods to grow nanowires via self-assembly, there is a key drawback in the need to find out the specific conditions appropriate for each system. In this sense, universal techniques to fabricate such nanowires from various organic materials have been sought for the continued progress of the related research field. Here we report one of the promising and facile methodologies to quantitatively produce nanowires with controlled geometrical parameters. In this method, referred to as "Single Particle-Triggered Linear Polymerization (STLiP)", organic thin films on a supporting substrate were irradiated with high-energy charged particles, accelerated by particle accelerators. Each particle penetrates from the top of the films to the substrate while gradually releasing kinetic energy along its trajectory (ion track), generating reactive intermediates such as radical species that eventually induce propagation reactions. The resulting polymerized products were integrated into nanowires with uniform diameter and length that can be isolated via development with appropriate organic solvents. Considering the widely applicable nature of STLiP to organic materials, the present technique opens a new door for access to a number of functional nanowires and their assembly.