Nano

With the advancements in nanotechnology, the interaction between nanotechnology, society and environment has increased. Nanotherapeutics and nanopharmaceuticals have allowed facilitation of earlier and more precise diagnosis, reduced side effects, improved targeted therapies and efficacy of drugs. Likewise, nanotechnology has helped in improving the quality of environment by solving issues of air pollution, water remediation and waste management with the help of nanoproducts such as nanofilters, nanophoto catalysts, nanoadsorbents and nanosensors. Moreover, nanopesticides, nanofood, anti-bacterial nanopackaging, nanofertilizers and many other products have helped food and agriculture sector to grow. There are innumerable products on shelf based on nanotechnology impacting almost every sector. However, nanotechnology like any other technology if used unchecked and unregulated can be a cause of social, environmental, legal and ethical concerns. Therefore, it is crucial to consider these challenges in addition to the promises and opportunities nanotechnology has to offer. This review has highlighted the immense importance of nanotechnology by discussing its applications especially in medicine, environmental sciences and food and agriculture sectors. Closely studying these aspects will allow us to discover gaps, obstacles and potential solutions for responsible nanotechnology development and deployment. Understanding these concerns and challenges is also critical for policymakers, researchers, industrialists and society as a whole in order to promote ethical practices and informed decision-making. This review will help to contribute to the continuing discourse and raise ethical awareness in the field of nanotechnology thence minimizing the harm while maximizing the benefits.

Hydroxyapatite (HA) is a highly biocompatible material that has similar properties to human bone. Researchers have adopted different methods for the synthesis of HA from different natural sources. This paper addresses the synthesis method of nano-hydroxyapatite (n-HA) from Hilsha Fishbone. The synthesized n-HA has been characterized by UV, FTIR, TEM, XRD and cytotoxicity analysis. The successful synthesis of n-HA has been confirmed by the peak formation in the UV analysis. The presence of functional groups has been identified by the FTIR analysis. According to the TEM images, the synthesized n-HA is irregular in size and shape. Based on the XRD analysis, the formation of crystals by the n-HA has been assured. The in-vitro cytotoxicity analysis confirmed the bio-safety of the synthesized n-HA. Based on the findings, the synthesized n-HA can be applied in different biomedical applications.

Nanomaterials are promising alternatives to antibiotics with the potential to handle the menace of emerging multidrug resistance in pathogenic microbes. We report a simple biosynthetic approach to prepare Ag nanoparticles (NPs) with strong antibacterial and antifungal actions by using Piper nigrum fruit extract as a bioreducing agent. The biosynthesized material was characterized by SEM, AFM, TEM, HRTEM, XRD and UV–Visible absorption spectroscopy. SEM, AFM and TEM analyses provided evidence that the average diameter of the Ag NPs was 18nm, while XRD and HRTEM confirmed the FCC structure of Ag NPs. The biosynthesized Ag NPs demonstrated extremely strong antibacterial activity against Bacillus oceanisediminis and Escherichia coli, and showed extremely strong antifungal action against Schizosaccharomyces pombe, inhibiting their growth at very low concentrations of 3$\mu$g/mL, 4$\mu$g/mL and 3$\mu$g/mL, respectively. The molecular origin of their antibacterial and antifungal activity was studied using various molecular and biochemical assays. The results of these assays revealed a major role for reactive oxygen species (ROS) in the antifungal and antibacterial actions of the biosynthesized Ag NPs. Furthermore, morphological changes in cells and cell wall damage upon Ag NP treatment were observed by scanning electron microscopy. In addition, significant enhancement in protein leakage and fragmentation of DNA was also observed upon treatment of S. pombe, B. oceanisediminis and E. coli with Ag NPs. In conclusion, the observed extremely strong antibacterial and antifungal activities of biosynthesized Ag NPs are due to the oxidative stress triggered by ROS, causing cell wall damage and subsequent protein leakage and DNA fragmentation.

Zinc oxide (ZnO) has demonstrated significant potential as a photocatalyst for the wastewater treatment. However, its wide bandgap leads to inefficient light utilization and rapid carrier recombination, which inhibits its photocatalytic activity. To overcome these limitations, we employed a hydrothermal method to synthesize Ag/ZnO composite microspheres with different concentrations of Ag nanoparticles. By utilizing Ag complexed with ZnO, the Ag/ZnO composite photocatalysts were made to have a narrower bandgap and a broadened light response range, as well as the red-shift phenomenon at the absorption edge. In addition, Ag nanoparticles can act as electron traps to efficiently capture electrons and minimize the recombination of photoexcited carriers for improved photocatalytic performance. Compared with other concentrations of ZnO microspheres and pure ZnO microspheres, the 5% Ag/ZnO composite microspheres exhibited excellent degradation performance when exposed to a xenon lamp, with 90.1% degradation of rhodamine B (RhB) solution in 100min. Incorporating trapping agents in experimental studies has indicated that the RhB degradation process is significantly influenced by •O${}_2^{-}$, while the impact of •OH and h${}^{+}$ were relatively weak. Thus, Ag/ZnO nanocomposites hold great promise as materials for use in wastewater treatment.

CuFeS₂ has many advantages, like high electrical conductivity, multiple redox centers, natural abundance and nontoxic. However, the low capacitance limits their application. In this work, we use carbon spheres (CS) prepared from starch to modify CuFeS₂. The prepared CuFeS₂/CS shows special structures with the CS as the core and CuFeS₂ as the shell. These CuFeS₂/CS nanocomposites show improved capacitive performance. CuFeS₂/CS has a specific capacitance of 349.4Fg${}^{-1}$ at 0.5Ag${}^{-1}$, four times that of pristine CuFeS₂ (88.8Fg${}^{-1})$, which might be attributed to the increased electrolyte diffusion capacity. The cyclic stability is also slightly improved, from 86.4% of the pristine CuFeS₂ to 90.5% of the CuFeS₂/CS nanocomposites due to the rigid structure of both crystal CuFeS₂ and firm CS. These CuFeS₂/CS nanocomposites are expected to be used in high-performance supercapacitor applications.

Due to advancements in Micro-Electro-Mechanical Systems (MEMS) fabrication technologies, researchers are incorporating numerous innovations in the design of capacitive pressure sensors (CPS). This work aims to present a novel CPS design using a plano-convex substrate to enhance the capacitance and sensitivity. Diaphragm deflection occurs due to its elastic property when pressure is applied to the diaphragm. This deflection reduces the distance between the diaphragm and substrate, thereby remarkably increasing capacitance. The Plano-Convex design offers added advantages of increased contact area between the diaphragm and substrate under applied pressure, hence significantly enhancing sensor sensitivity and range. More efficient and miniaturized CPSs are in high demand in medical instrumentation, aerospace, aviation, power plants and automotive industries. This work presents all the required mathematical calculations, modeling and simulations to support the proposed design. The diaphragm deflection simulation concerning pressure is conducted using COMSOL Multiphysics, while MATLAB is employed for analytical simulations related to changes in capacitance and capacitive sensitivity.

The sulfuric acid-doping polyaniline (H-PANI-HSO₄) are applied to conduct the electrochemical measurement and simulation calculation to investigate the capacitance, electronic structure and energy band properties. The H-PANI-HSO₄ growing on graphite carbon paper (H-PANI-HSO₄/GCP) is applied as an electroactive electrode to investigate electrochemical properties. The Faradaic capacitance of H-PANI-HSO₄/GCP electrode is ascribed to the reversible redox reaction of bisulfate anion doping/dedoping protonated PANI (H-PANI). Cyclic voltammetry measurement at a scan rate of 5mVs${}^{-1}$ determines an equivalent mean response current of 0.64Ag${}^{-1}$ and a capacitance of 128.35Fg${}^{-1}$. Galvanostatic charge–discharge measurement determines specific capacitance from 129.06 to 116.88Fg${}^{-1}$ at current densities from 0.5 to 2.5Ag${}^{-1}$. Cyclic voltammetry-based capacitance at equivalent current density of 0.64Ag${}^{-1}$ is in accordance with galvanostatic charge–discharge-based capacitance at the current density of 0.57Ag${}^{-1}$. Electrochemical impedance spectrum measurements indicate that H-PANI-HSO₄/GCP exhibits lower charge-transfer resistance, much lower Warburg resistance, higher quasicapacitance than H-PANI-HSO₄ to approaching ideal capacitor. Density functional theory calculations indicate that H-PANI-HSO₄ has a higher density of states (10.6 electron/eV) and lower bandgap energy (0.481eV) than H-PANI (5.24 electron/eV, 1.449eV), indicating its enhanced electronic conductivity. The electronic bandgap energy is accordingly decreased from 0.263eV for H-PANI-HSO₄/GCP to 0 for H-PANI-HSO₄/GCP. Electrochemical measurement and simulation calculation investigation proves that H-PANI-HSO₄/GCP electrode with anion-doped and protonated state exhibits higher electronic conductivity and capacitance performance to act as superior electroactive material.