In this investigation, the photophysical properties and interaction mechanisms of Janus green blue (JGB) dye with polyanions were systematically studied using spectroscopic techniques. The absorption spectral analysis revealed that JGB binds cooperatively to sodium alginate, leading to dye stacking along the polymer chain. The interaction of JGB dye with DNA was characterized by the emergence of a metachromatic peak at 564 nm, indicating the formation of dye aggregates.
View Article and Find Full Text PDFCarbon dots (CDs), including carbon quantum dots, graphene quantum dots, carbon nanodots, and polymer dots, have gained significant attention due to their unique structural and fluorescence characteristics. This review provides a comprehensive overview of the classification, structural characteristics, and fluorescence properties of CDs, followed by an exploration of various fluorescence sensing mechanisms and their applications in gene detection, nucleolus imaging, and gene delivery. Furthermore, the functionalization of CDs with diverse surface ligand molecules, including dye molecules, nucleic acid probes, and metal derivatives, for sensitive nucleic acid detection is systematically examined.
View Article and Find Full Text PDFIn this study, cationic carbon dots (CDs) were prepared from -phenylenediamine (PDA) a one-step hydrothermal method and used to trigger the aggregation and dispersion of gold nanoparticles (AuNPs) for the colorimetric detection of nucleic acids. Physicochemical characterization results revealed that the CDs are enriched with positively charged surface functional groups with an average size of ∼11 nm. The interaction between the CDs and AuNPs was confirmed fluorescence and absorption studies.
View Article and Find Full Text PDFThe development of nanoclusters based on incorporating biomolecules like proteins, lipids, enzymes, DNA, surfactants, and chemical stabilizers creates a stable and high fluorescence bio-sensors promising future due to their high sensitivity, high level of detection and better selectivity. This review addresses a comprehensive and systematic overview of the recent development in synthesizing metal nanocluster by various strategized synthesis techniques. Significantly, the application of nanometal clusters for the detection of various food contaminants such as microorganisms, antibodies, drugs, pesticides, metal contaminants, amino acids, and other food flavors have been discussed briefly concerning the detection techniques, sensitivity, selectivity, and lower limit of detection.
View Article and Find Full Text PDFIn this study, dual-emissive carbon dots (CDs) were prepared using -phenylenediamine (PDA) and phytic acid (PA) precursors via a one-pot-hydrothermal method. The photophysical, morphological, and structural characterization of CDs was carried out using absorption, fluorescence, Fourier transform infrared (FT-IR) spectroscopy, nuclear magnetic resonance (NMR), and high-resolution transmission electron microscopy (HR-TEM) analysis. The as-prepared CDs displayed dual-fluorescence peaks at 525 and 620 nm upon excitation at 450 nm.
View Article and Find Full Text PDFUpconversion nanoparticles (UCNPs) are known to possess unique characteristics, which allow them to overcome a number of issues that plague traditional fluorescence probes. UCNPs have been employed in a variety of applications, but it is arguably in the realm of optical sensors where they have shown the most promise. Biomolecule conjugated UCNPs-based fluorescence probes have been developed to detect and quantify a wide range of analytes, from metal ions to biomolecules, with great specificity and sensitivity.
View Article and Find Full Text PDFThe versatile photophysicalproperties, high surface-to-volume ratio, superior photostability, higher biocompatibility, and availability of active sites make graphene quantum dots (GQDs) an ideal candidate for applications in sensing, bioimaging, photocatalysis, energy storage, and flexible electronics. GQDs-based sensors involve luminescence sensors, electrochemical sensors, optical biosensors, electrochemical biosensors, and photoelectrochemical biosensors. Although plenty of sensing strategies have been developed using GQDs for biosensing and environmental applications, the use of GQDs-based fluorescence techniques remains unexplored or underutilized in the field of food science and technology.
View Article and Find Full Text PDFSpectrochim Acta A Mol Biomol Spectrosc
January 2022
Adenosine triphosphate (ATP) is an energy molecule of significant importance, and, the monitoring of ATP in living cells is considerable for the clinical diagnosis of many related diseases, including cancer. Upconversion nanoparticles (UCNPs) have recently been attracting widespread interest in biomedical applications due to their chemical and thermal stability, high sensitivity, good biocompatibility, and excellent tissue penetration. Herein, a Cy3-aptamer-cDNA- UCNPs nanosensor was synthesized, based on the luminescence resonance energy transfer (LRET) between UCNPs and Cy3 for monitoring ATP in living cells.
View Article and Find Full Text PDFPathogenic bacteria and their metabolites are the leading risk factor in food safety and are one of the major threats to human health because of the capability of triggering diseases with high morbidity and mortality. Nano-optical sensors for bacteria sensing have been greatly explored with the emergence of nanotechnology and artificial intelligence. In addition, with the rapid development of cross fusion technology, other technologies integrated nano-optical sensors show great potential in bacterial and their metabolites sensing.
View Article and Find Full Text PDFSpectrochim Acta A Mol Biomol Spectrosc
February 2021
In this study, a novel analytical approach is proposed for the identification of pesticide residues in tea by combining surface-enhanced Raman scattering (SERS) with a deep learning method one-dimensional convolutional neural network (1D CNN). First, a handheld Raman spectrometer was used for rapid on-site collection of SERS spectra. Second, the collected SERS spectra were augmented by a data augmentation strategy.
View Article and Find Full Text PDFNoble bimetallic and trimetallic nanoparticles (NBT-NPs) have superior biomedical applications as compared to their monometallic counterparts. The performance of these nanomaterials depends on their composition, shape and size. Hence, the controlled-synthesis of these nanomaterials is a hot area of research.
View Article and Find Full Text PDFMater Sci Eng C Mater Biol Appl
March 2020
Phytochemicals sources have been extensively used as reducing and capping agents for synthesis of nanoparticles (NPs). However, morphology-controlled synthesis and shape/size dependent applications of these NPs still need to be explored further, and there is a need to develop a way in which particular and optimized phytochemicals result in the desired NPs in lesser time and cost with higher reproducibility rate. The present study is focused on morphology-controlled synthesis and shape/size dependent application of silver NPs based on the fractionated phytochemicals of Elaeagnus umbellata extract (EU).
View Article and Find Full Text PDFA dual (colorimetric and fluorometric) method is described for sensitive and selective determination of the herbicide glyphosate. It is based on the use of a system composed of polyethylenimine-capped NaGdF:Yb,Er upconversion nanoparticles (UCNPs), copper(II) ions, hydrogen peroxide and 3,3',5,5'-tetramethylbenzidine. The physicochemical and photophysical properties of the polyethylenimine-capped UCNPs were characterized by various spectroscopic and microscopic techniques.
View Article and Find Full Text PDFThe present investigation elucidates a simple hydrothermal method for preparing nanostructured bismuth oxide (BiO) and carbon quantum dot (CQD) composite using spoiled (denatured) milk-derived CQDs. The formation of the CQD-BiO composite was confirmed by UV-vis absorption, steady-state emission, and time-resolved fluorescence spectroscopy studies. The crystal structure and chemical composition of the composite were examined by X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, and thermogravimetric analysis.
View Article and Find Full Text PDFIn the present study, the interaction of model transport proteins Human serum albumin (HSA) and Bovine serum albumin (BSA) with a photoactive dye, Azure B (AZB) were studied by spectroscopic and in silico methods. The absorption spectral behavior of AZB in the presence of varying concentrations of serum albumins (HSA and BSA) revealed the formation of dye aggregates within the protein cavity. The binding parameters computed from the emission quenching data showed that AZB bind to HSA and BSA with significant affinity and it was revealed that both the serum proteins (HSA and BSA) can bind AZB at more than one binding sites having at least one high-affinity binding site with different affinities (non-independent).
View Article and Find Full Text PDFIn the present investigation, we have systematically studied the binding mechanism of model protein human serum albumin (HSA) with gold/silver alloy nanoparticles (Au/Ag NPs) using multiple spectroscopic techniques. Absorption spectral studies of Au/Ag NPs in the presence of increasing concentrations of HSA resulted in a slight red shift of the surface plasmon resonance band (SPR) of Au/Ag NPs, suggesting changes in the refractive index around the nanoparticle surface owing to the adsorption of HSA. The results from high-resolution transmission electron microscopy (HR-TEM), dynamic light scattering (DLS), and zeta potential analysis substantiated the formation of a dense layer of HSA on the surface of Au/Ag NPs.
View Article and Find Full Text PDFIn the present work, we have carried out a detailed investigation on the binding interaction of acridine orange (AO) with borate capped gold nanoparticles (Au NPs) by absorption spectroscopy, steady state emission spectroscopy, time resolved fluorescence spectroscopy, high resolution transmission electron microscopy (HR-TEM), dynamic light scattering (DLS), zeta potential measurements, Fourier transform infrared (FT-IR) and Raman spectroscopy. The phenomena of hypochromism and the appearance of coupled localized surface plasmon resonance (LSPR) bands in the absorption spectral studies of the AO-Au NP system suggested the vital role of electrostatic interactions between AO dye and Au NPs. The results from HR-TEM and DLS measurements confirmed the formation of aggregated clusters of nanoparticles.
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