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In this paper, one of the great challenges faced by silicon-based biosensors is resolved using a biomaterial multilayer. Tiny biomolecules are deposited on silicon substrates, producing devices that have the ability to act as iridescent color sensors. The color is formed by a coating of uniform microstructures through the interference of light. The system exploits a flat, RNA-aptamer-coated silicon-based surface to which captured microbes are covalently attached. Silicon surfaces are encompassed with the layer-by-layer deposition of biomolecules, as characterized by atomic force microscopy and X-ray photoelectron spectroscopy. Furthermore, the results demonstrate an application of an RNA aptamer chip for sensing a specific bacterium. Interestingly, the detection limit for the microbe was observed to be 2 × 106 CFUmL-1 by visually observed color changes, which were confirmed further using UV-Vis reflectance spectrophotometry. In this report, a flexible method has been developed for the detection of the pathogen Sphingobium yanoikuyae, which is found in non-beverage alcohols. The optimized system is capable of detecting the specific target microbe. The simple concept of these iridescent color changes is mainly derived from the increase in thickness of the nano-ordered layers.

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This study reports the synthesis of silver nanoparticles using amino acid L-histidine as a reducing and capping agent as an eco-friendly approach. Fabricated L-histidine-capped silver nanoparticles (L-HAgNPs) were characterized by spectroscopic and microscopic studies. Spherical shaped L-HAgNPs were synthesized with a particle size of 47.43 ± 19.83 nm and zeta potential of -20.5 ± 0.95 mV. Results of the anticancer potential of L-HAgNPs showed antiproliferative effect against SiHa cells in a dose-dependent manner with an IC50 value of 18.25 ± 0.36 µg/mL. Fluorescent microscopic analysis revealed L-HAgNPs induced reactive oxygen species (ROS) mediated mitochondrial dysfunction, leading to activation of apoptotic pathway and DNA damage eventually causing cell death. To conclude, L-HAgNPs can act as promising candidates for cervical cancer therapy.

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Integration of semiconducting nanostructures with noble metal nanoparticles are turning highly desirable for cost efficient energy and environmental related applications. From this viewpoint, we report on a facile aqueous synthesis of polymer capped gold (Au) nanoparticles on free standing 2D layered structures of zinc oxide (ZnO) to result with ZnO/Au nanocomposites. Concentration of Au nanoparticles were observed to promote the preferential growth of ZnO along the (002) wurtzite plane. The ZnO/Au structures and their morphological dissemination was noted to be of few. This flake like structure was also noted to be greatly influenced by the concentration of Au in the colloidal blend. Optical band edge transformations noted in the absorption spectra across the lower wavelength region and the shift in surface plasmon resonance (SPR) towards the red region of the visible spectrum signify the improved absorptivity of the heterostructures along the visible spectrum. These heterostructures exhibited remarkable visible light driven photocatalytic activity (99% efficiency) on par with pristine ZnO. The findings also attest this new class of composite structures to open up new openings in diversified solar energy conversion related functions.

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In the present study, a simple and a selective colorimetric method for pheromone detection to diagnose estrus in cattle was established based on the l-tyrosine functionalized silver nanoparticles (l-TyrAgNPs). The synthesized silver nanoparticles was spotted by color change (colorless to pale yellow) due to surface plasmon resonance (SPR). In order to confirm, Ag nanoparticles was characterized by field emission scanning electron microscopy (FESEM), dynamic light scattering (DLS) and zeta potential, X-ray diffraction (XRD) and UV- Vis spectrophotometer. It was found that the pre-colored Ag colloids could be turned from yellow to reddish-brown by the addition of the sex pheromones such as acetic acid or propionic acid, which may have potential application in the colorimetric sensor. The augmented optical nature of nanoparticles furnishes a suitable base to develop a colorimetric sensor for bovine sex pheromones detection. In addition, the computational analyses are critically required to validate residual interactions of bovine odorant-binding protein (OBP) with pheromones. The method was successfully applied to the detection of acetic acid or propionic acid using a biological molecule l-Tyr AgNPs. These results clearly indicate that the biosynthesis of l-Tyr AgNPs can be used as a promising colorimetric sensor for accurate time of estrus prediction in bovine.

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The preeminent treatments for neurodegenerative disease are often unavailable due to the poor accessibility of therapeutic drugs. Moreover, the blood-brain barrier (BBB) effectively blocks the transfer of cells, particles and large molecules, ie, drugs, across the brain. The most important challenge in the treatment of neurodegenerative diseases is the development of targeted drug delivery system. Theranostic strategies are known to combine therapeutic and diagnostic capabilities together. The aim of this review was to record the response to treatment and thereby improve drug safety. Nanotechnology offers a platform for designing and developing theranostic agents that can be used as an efficient nano-carrier system. This is achieved by the manipulation of some of the properties of nanoparticles (NPs), thereby enabling the attachment of suitable drugs onto their surface. The results provide revolutionary treatments by stimulation and thus interaction with targeted sites to promote physiological response with minimum side effects. This review is a brief discussion of the administration of drugs across the brain and the advantages of using NPs as an effective theranostic platform in the treatment of Alzheimer's, Parkinson's, epilepsy and Huntington's disease.

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This work demonstrates the effective surface functionalization of Ag, Au and bimetallic Ag-Au nanoparticles using l-histidine for colorimetric detection of dopamine (DA) which plays majorly in recognizing the neurological disorder. l-Histidine (l-His) capped Ag, Au, and bimetallic Ag-Au nanoparticles are characterized using physico-chemical techniques. The optical behaviour of nanoparticles has been analysed at various time intervals using UV-Vis absorption spectroscopy. FT-IR results provide the evidence of chemical bonding between l-histidine and metal nanoparticles. Its structure with the capping of l-His was clearly shown in HR-TEM images. The average size of nanoparticles has calculated from TEM image fringes are 11nm, 5nm and 6.5nm respectively, matches with crystals size calculated from X-ray diffraction pattern. Enhanced optical nature of nanoparticles provides the best platform to develop a colorimetric-based biosensor for DA detection. After addition of DA, a rapid colour change has been noted in colloids of nanoparticles. The substantial changes in absorbance and λmax in metal nanoparticles respect to DA concentration have been observed and formulated. This is one of the successive methods for trace level determination of DA and will be going to a significant material for designing biosensor to determine DA in real extracellular body fluids.

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Estrus detection in buffaloes has been a major concern for decades, and lack of reliable methods affects their effective reproductive management. Luteinizing hormone (LH) detection in urine is in practice for several mammals for timed insemination, whereas very few reports are available on buffalo urinary LH. The focus of this study is to detect the presence of LH in buffalo urine, quantitate variation in urinary LH during different estrous cycle phases and examine the duration of mid-cycle LH window. Nearly hundred buffaloes were examined, longitudinal urine samples (n=42) were collected from seventeen animals and classified into respective phases based on several estrus detection parameters. The urinary LH was detected using bovine LH ELISA kit validated for serum/plasma/tissue homogenate. Detection of buffalo LH in the neat urine convincingly proved the competence of the bovine LH kit. Variation in the LH range was observed between different phases of estrous cycle and significant fold variation (P<0.05) was noticed during estrus phase (1.01±0.23) with average baseline value of 46.73±3.36mIU/mL. Interestingly, an extended window (A1-A3) of mid-cycle LH surge was observed due to its lingering excretion in urine. The results, altogether, revealed that LH can be detected in buffalo urine with noticeable fold variation during estrus phase and the extended LH window intensifies the chance of ovulation prediction for timed insemination.

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