Development of highly sensitive electrochemical immunosensor using PPy-MoS2-based nanocomposites modified with 90 MeV C6+ ion beams.

The evaluation of electrochemical sensing activity of hydrothermally derived PPy-MoS2-based nanocomposites subjected to 90 MeV C6+ ion beam with fluence ranging, 1.0 × 1010-1.0 × 1013 ions/cm2, is reported. Cross-linking, chain scissioning, and ion track formation could occur in the irradiated systems, as revealed from Fourier transform infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FE-SEM) studies. Electrochemical studies, viz., cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were performed in 0.1 M phosphate buffer solution (PBS) containing 5 mM K3[Fe(CN)6] as redox probe. High redox activity, lower charge transfer resistance (Rct = 490 Ω) and larger electroactive area (A = 0.4485 cm2) were obtained in case of the composite system irradiated with a fluence of 3.5 × 1011 ions/cm2. Immunosensor fabrication was executed via immobilization of mouse IgG over the pristine and post-irradiated electrodes. Afterwards, differential pulse voltammetry (DPV) was performed within the potential window - 0.2 to + 0.6 V (vs. Ag/AgCl) for the detection of specific analyte. Noticeably, the electrode system irradiated with a fluence of 3.5 × 1011 ions/cm2 is characterized by a lower limit of detection (LOD) of 0.203 nM and a higher sensitivity value of 10.0 µA mL ng-1 cm-2. The energetic particle irradiation at a modest fluence can offer beneficial effects to the PPy-MoS2-based nanohybrid system providing immense scope as advanced electrochemical biosensor.

Monstera deliciosa mediated single step biosynthesis of gold nanoparticles by bottom-up approach and its non-antimicrobial properties.

In this study, we have stated the green biosynthesis of gold nanoparticles (AuNPs) by utilizing the extract of Monstera deliciosa leaves (MDL) as a reducing agent. Biosynthesized flat, thin, and single-crystalline gold nanotriangles obtained through centrifugation are then analyzed by different characterization techniques. The UV - visible absorption spectra of AuNPs exhibited maxima bands in the range of 500-590 nm, indicating a characteristic of AuNPs. XRD analysis revealed the formation of the (111)-oriented face-centered cubic (FCC) phase of AuNPs. ATR-IR spectra showed signatures of stretching vibrations of O-H, C-H, C=C, C=O, C-O, and C-N, accompanied by CH3 rocking vibrations present in functional groups of biomolecules. FESEM images confirmed spherical nanoparticles with an average diameter in the range of 53-66 nm and predominantly triangular morphology of synthesized AuNPs within the size range of 420-800 nm. NMR, GC-MS, and HR-MS studies showed the presence of different biomolecules, including phenols, flavonoids, and antioxidants in MDL extracts, which play a crucial role of both, reducing as well as stabilizing and capping agents to form stable AuNPs by a bottom-up approach. They were then investigated for their antibacterial assay against Gram-positive (S. aureus, B. subtilis) and Gram-negative (E. coli, P. aeruginosa) microorganisms, along with testing of antifungal potential against various fungi (Penicillium sp., Aspergillus flavus, Fusarium oxysporum, Rhizoctonia solani) using the well diffusion method. Here, biosynthesized AuNPs showed non-antimicrobial properties against all four used bacteria and fungi, showing their suitability as a contender for biomedical applications in drug delivery ascribed to their inert and biocompatible nature. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-023-03898-0.

Electrochemically deposited bimetallic SERS substrate for trace sensing of antibiotics.

Electrochemically deposited bimetallic copper-gold nanoparticles on indium tin oxide (Cu-AuNPs on ITO) glass are demonstrated to be a sensitive and reproducible surface-enhanced Raman scattering (SERS) platform. An optimal signal enhancement with reasonably good degree of homogeneity was obtained by tuning the deposition parameters of the electrochemical setup. For Raman active analytes such as malachite green (MG) and rhodamine 6G (R6G), the developed SERS platform yields a limit of detection (LOD) of 0.75 nM. The usability of the proposed SERS platform has been realized through detection of two important antibiotics namely sulfamethoxazole (SFZ) and tetracycline hydrochloride (TCH) commonly used in egg farms. Furthermore, a machine learning (ML)-based model coupled with a dimensionality reduction technique-principal component analysis (PCA)-has been implemented to classify the targeted analytes in egg samples.

CsPbBr3 perovskite quantum dot decorated ZIF-8 MOF: a selective dual recognition fluorometric visual probe for 4-nitroaniline and rhodamine blue.

The uses of highly luminescent perovskite quantum dots in real analytical detection were limited by their supersensitive nature. Here, we have designed a CsPbBr3 perovskite based fluorometric sensor by integrating them with a zeolitic imidazole framework (ZIF-8) via an in situ one step technique and established its stability in aqueous and other polar solvents. The CsPbBr3@ZIF-8 luminescence sensor functioned excellently for the trace detection of 4-nitroaniline and rhodamine blue dye molecules with a detection limit value of 8.367 ppb and 0.088 ppm, respectively. A comprehensive investigation found that the quenching of the fluorescence signal occurred via fluorescence resonance energy transfer (FRET) for rhodamine blue dye and a H-bonding interaction induced trap density mediated quenching mechanism was responsible for 4-NA detection. The potential of this suggested sensor as a cheap portable test paper probe for analyte detection was also explored. This study introduces CsPbBr3 as a cutting-edge sensing platform for industrial pollutants such as dye molecules and nitroaromatics.

Biogenic nanosized gold particles: Physico-chemical characterization and its anticancer response against breast cancer.

With the advancement of nanotechnology, the nano-sized particles make an imprint on our daily lives.The present investigation revealed that biomolecules present in seed exudates of Vigna radiata are responsible for the synthesis of AuNPs, confirmed by the routine characterization techniques. Anticancer efficacy showed by AuNPs might be due to the release of phytochemicals in the exudate which is being adsorbed on the surface of AuNPs referencing their anticancer efficacy against the tested breast cancer cell lines. Inhibition of clonogenicity and cell cycle arrest at G2/M phase then apoptosis of AuNPs was also observed, but found nontoxic to the human PBMC cells which further confirms its biocompatible property Among the various physicochemical study, present AuNPs shows unique information, they show photoluminescent property which may be used for bioimaging purposes. However, further molecular analysis needs to be explored to understand the underlying mechanism for therapeutic and biomedical application.

Nutritional assessment study and role of green silver nanoparticles in shelf-life of coconut endosperm to develop as functional food.

Tender coconut water is a pure and nutritious drink which play important role as nutraceuticals and pharmaceuticals contributes to the rapid growth of the functional food industry. In the mean-time the safety and shelf-life of the food is crucial for the both product as well as consumers. The intervention or application of nanotechnology gives immense a solution for the prolonged sustainability of the food products. This work reports on the nature of physiological changes of coconut liquid endosperm along with the interaction of its DNA with green route synthesized Ag nanoparticles (AgNPs) using Garuga pinnata leaf, an important ethnomedicinal plant. The physical and nutritional study of the coconut water were carried by UV-visible, XRD, NMR analysis whereas the synthesized Ag nanoparticles (AgNPs) were characterized by UV-Visible spectrophotometer, Raman Spectroscopy, DLS, AFM and FE-SEM analysis. The pH of the endosperm was found to decrease from 6.31 to 4.01, following an exponential decay trend and giving a decay constant of ~8.8 h. The broad absorption peak at ~310 nm gradually turns featureless with elapse of time. The proton nuclear magnetic resonance (H1-NMR) spectrum essentially revealed the presence of esters or organic acids, confirming a sudden fall in the rate of intensity in the immature coconut endosperms as compared to the matured coconut cases. While the pentosyl methyl group (~1.4-1.5 ppm) concentration is observably lowered, free amino acid (~1 ppm) is apparently suppressed in the former specimen. Gel electrophoresis of 10 kb DNA with Ag nanoparticles (AgNPs) showed a gradual decrease of band intensity for a concentration varying between 3:1 and 1:1. The less intense band was due to the lack of migration of DNA into the micropores of the gel as a consequence of interaction of negatively charged DNA with negatively charged AgNPs. The study of DNA interaction with AgNPs could help identifying and addressing the nature of degradation process while considering prevention from microbial attack and make the coconut water as potential functional food entity.

Perceptible exciton-to-trion conversion and signature of defect mediated vibronic modes and spin relaxation in nanoscale WS2 exposed to γ-rays.

In this work, we report manifested optical, optoelectronic and spin-spin relaxation features of a few layered tungsten disulphide (WS2) nanosheets subjected to energetic γ-photons (∼1.3 MeV) emitted from a Co60 source. Upon intense irradiation (dose = 96 kGy), a slight departure from the pure hexagonal phase was realized with the introduction of the trigonal phase at large. Moreover, in the Raman spectra, as a consequence of the radiation-induced effect, an apparent improvement of the E-to-A mode intensity and a reduction in phonon lifetimes have been realized, with the latter being dependent on the linewidths. The emergence of the new peak (D) maxima observable at ∼406 cm-1 in the Raman spectra and ∼680 nm in the photoluminescence (PL) spectra can be attributed to the introduction of defect centres owing to realization of sulphur vacancies (V S) in the irradiated nanoscale WS2. Additionally, neutral exciton to charged exciton (trion) conversion is anticipated in the overall PL characteristics. The PL decay dynamics, while following bi-exponential trends, have revealed ample improvement in both the fast parameter (0.39 ± 0.01 ns to 1.88 ± 0.03 ns) and the slow parameter (2.36 ± 0.03 ns to 12.1 ± 0.4 ns) after γ-impact. We attribute this to the finite band gap expansion and the incorporation of new localized states within the gap, respectively. A declining exciton annihilation rate is also witnessed. The isotropic nature of the electron paramagnetic resonance spectra as a consequence of γ-exposure would essentially characterize a uniform distribution of the paramagnetic species in the system, while predicting a three-fold improvement of relative spin density at 96 kGy. Exploring defect dynamics and spin dynamics in 2D nanoscale systems does not only strengthen fundamental insight but can also offer ample scope for designing suitable components in the areas of miniaturized optoelectronic and spintronic devices.

Biogenic synthesis of silver nanoparticles from Cassia fistula (Linn.): In vitro assessment of their antioxidant, antimicrobial and cytotoxic activities.

The present study reports on biogenic-synthesised silver nanoparticles (AgNPs) derived by treating Ag ions with an extract of Cassia fistula leaf, a popular Indian medicinal plant found in natural habitation. The progress of biogenic synthesis was monitored time to time using a ultraviolet-visible spectroscopy. The effect of phytochemicals present in C. fistula including flavonoids, tannins, phenolic compounds and alkaloids on the homogeneous growth of AgNPs was investigated by Fourier-transform infrared spectroscopy. The dynamic light scattering studies have revealed an average size and surface Zeta potential of the NPs as, -39.5 nm and -21.6 mV, respectively. The potential antibacterial and antifungal activities of the AgNPs were evaluated against Bacillus subtilis, Staphylococcus aureus, Candida kruseii and Trichophyton mentagrophytes. Moreover, their strong antioxidant capability was determined by radical scavenging methods (1,1-diphenyl-2-picryl-hydrazil assay). Furthermore, the AgNPs displayed an effective cytotoxicity against A-431 skin cancer cell line by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, with the inhibitory concentration (IC50) predicted as, 92.2 ± 1.2 µg/ml. The biogenically derived AgNPs could find immense scope as antimicrobial, antioxidant and anticancer agents apart from their potential use in chemical sensors and translational medicine.

Physical and biophysical assessment of highly fluorescent, magnetic quantum dots of a wurtzite-phase manganese selenide system.

Combining fluorescence and magnetic features in a non-iron based, select type of quantum dots (QDs) can have immense value in cellular imaging, tagging and other nano-bio interface applications, including targeted drug delivery. Herein, we report on the colloidal synthesis and physical and biophysical assessment of wurtzite-type manganese selenide (MnSe) QDs in cell culture media. Aiming to provide a suitable colloidal system of biological relevance, different concentrations of reactants and ligands (e.g., thioglycolic acid, TGA) have been considered. The average size of the QDs is ∼7 nm, which exhibited a quantum yield of ∼75% as compared to rhodamine 6 G dye(®). As revealed from time-resolved photoluminescence (TR-PL) response, the near band edge emission followed a bi-exponential decay feature with characteristic times of ∼0.64 ns and 3.04 ns. At room temperature, the QDs were found to exhibit paramagnetic features with coercivity and remanence impelled by TGA concentrations. With BSA as a dispersing agent, the QDs showed an improved optical stability in Dulbecco's Modified Eagle Media(®) (DMEM) and Minimum Essential Media(®) (MEM), as compared to the Roswell Park Memorial Institute(®) (RPMI-1640) media. Finally, the cell viability of lymphocytes was found to be strongly influenced by the concentration of MnSe QDs, and had a safe limit upto 0.5 µM. With BSA inclusion in cell media, the cellular uptake of MnSe QDs was observed to be more prominent, as revealed from fluorescence imaging. The fabrication of water soluble, nontoxic MnSe QDs would open up an alternative strategy in nanobiotechnology, while preserving their luminescent and magnetic properties intact.

Creation and regulation of ion channels across reconstituted phospholipid bilayers generated by streptavidin-linked magnetite nanoparticles.

In this work, we explore the nature of ion-channel-like conductance fluctuations across a reconstituted phospholipid bilayer due to insertion of ∼100 nm sized, streptavidin-linked magnetite nanoparticles under static magnetic fields (SMFs). For a fixed bias voltage, the frequency of current bursts increases with the application of SMFs. Apart from a closed conductance state G(0) (≤14 pS), we identify four major conductance states, with the lowest conductance level (G(1)) being ∼126 pS. The number of channel events at G(1) is found to be nearly doubled (as compared to G(0)) at a magnetic field of 70 G. The higher-order open states (e.g., 3G(1), 5G(1)) are generally observable at larger values of biasing voltage and magnetic field. When the SMF of 145 G is applied, the multiconductance states are resolved distinctly and are assigned to the simultaneous opening and closing of several independent states. The origin of the current bursts is due to the instantaneous mechanical actuation of streptavidin-linked MNP chains across the phospholipid bilayer. The voltage-controlled, magnetogated ion channels are promising for diagnoses and therapeutic applications of excitable membranes and other biological systems.

Physical and biophysical characteristics of nanoscale tungsten oxide particles and their interaction with human genomic DNA.

Nanoscale tungsten oxide (WO3) particles were synthesized via a user-friendly solvothermal cum reduction route using sodium tungstanate (Na2WO4) and cetyl trimethyl ammonium bromide (C19H42NBr) as reactants. The X-ray diffraction and transmission electron microscopy studies have revealed monoclinic phase of WO3 with an average crystallite size of 40 nm and competitive crystallographic orientation along (002), (020), (200) planes. After extracting human genomic DNA from human blood by a standard protocol (Qiagen-Kit method), they were conjugated with nanoscale WO3 particles in varying molar concentrations. The biophysical interaction of DNA bound nanoparticles were characterized by Fourier transform infra-red spectroscopy, photoluminescence spectroscopy, agarose gel-electrophoresis and polymerase chain reaction. Understanding physical and biophysical aspects of unconjugated and DNA conjugated WO3 would provide scope for biosensing applications.