Chromium contamination in aquatic systems represents a major environmental and public health concern due to the high toxicity and mobility of its hexavalent species. In this work, α-Sulfophenylacetic acid functionalized gold nanoparticles (α-SPAA-AuNPs) were developed as a dual-functional colorimetric platform for the selective detection and removal of chromium ions in aqueous media. The functionalized nanoparticles enable ultrasensitive sensing of Cr(III) and Cr(VI) through analyte-induced aggregation, producing a distinct color transition resulting from localized surface plasmon resonance changes. By integrating Cr(VI), Cr(III), ethylenediaminetetraacetic acid (EDTA), and ascorbic acid (AA) as chemical inputs, molecular logic gate operations including AND, OR, and INHIBITOR were successfully constructed. The proposed sensing system exhibited excellent selectivity toward chromium species over other competing metal ions. The limits of detection were determined to be 15.6 ppb for Cr(III) and 20.8 ppb for Cr(VI) after reduction with AA. The sensing mechanism is attributed to coordination interactions between chromium ions and the carboxyl functional groups of α-Sulfophenylacetic acid on the nanoparticle surface, leading to nanoparticle aggregation. Furthermore, the platform demonstrated practical applicability through successful analysis of environmental water samples including drinking water, tap water, and lake water, highlighting its potential for environmental monitoring and remediation of chromium contamination.
Nanoparticles are increasingly being employed in a variety of industrial and environmental applications. In this study, we aimed to develop a sustainable method for synthesizing silver nanoparticles and to evaluate their potential as algal growth inhibitors. A seedless protocol was established using ascorbic acid and polyvinylpyrrolidone (PVP) to obtain spherical silver nanoparticles, thereby avoiding the use of strong reducing agents. The nanoparticles were characterized by UV-Vis spectroscopy, transmission electron microscopy (TEM), and IR spectroscopy. Since microalgae and other marine organisms often grow on the surfaces of boats, ships, and other human-made devices in aquatic environments, antifouling products are necessary to prevent unwanted fouling. The algal growth inhibition capacity of the synthesized silver nanoparticles was assessed using two marine diatoms Cylindrotheca Closterium and Skeletonema marinoi. The results revealed a marked inhibitory effect on algal proliferation in treated samples compared to controls. Overall, this study demonstrates the effectiveness of the proposed synthetic method and paves the way for the use of these silver nanoparticles as a tool for controlling microalgal growth.
Artisanal and Small-scale Gold Mining (ASGM) operations increasingly adopt mechanized comminution, assuming it universally improves gold recovery. This case study challenges that generalized approach through a comparative field performance evaluation of two gravity recovery circuits processing saprolite ore in Suriname: a traditional direct sluicing system (IST) and a mechanized hammer mill-centrifuge system (HS). Operational parameters and fractional gold deportment were evaluated using a reconstituted head grade methodology to mitigate the fundamental sampling error inherent to high-nugget deposits. Feed characterization revealed that approximately 80
Gold-based materials are widely used in electronics, catalysis, and biomedicine due to their excellent conductivity, chemical stability, and biocompatibility; however, their low strength and poor wear resistance limit structural applications. Microalloying, defined as the addition of trace elements (< 0.5 wt
Gold nanoparticles (AuNPs) exhibit exceptional physicochemical properties, notably localized surface plasmon resonance (LSPR), enabling diverse applications in biomedicine, molecular imaging (CT/PAI/MRI), photothermal therapy (PTT), and targeted drug delivery. This review systematically examines synthesis strategies, emphasizing pulsed laser ablation in liquid (PLAL) as a surfactant-free, eco-friendly “top-down” method producing pristine 5–50 nm AuNPs via plasma plume confinement and cavitation-induced nucleation. Complementary “bottom-up” green biosynthesis leverages plant/fruit extracts (polyphenols/flavonoids), microorganisms, and fungi (nitrate reductase) to yield biofunctionalized AuNPs (10–80 nm) with inherent stability for theranostics. Comparative analyses highlight PLAL’s superiority in purity/yield compared to chemical methods, while biological methods excel in scalability and multifunctionality. Shape-dependent plasmonic heating: nanorods achieve ΔT = 45–55 °C vs. spheres (25 °C), underpinning PTT efficacy. The review elucidates targeting strategies (passive EPR vs. active ligand-receptor), hybrid imaging, and challenges, including EPR heterogeneity, synthesis reproducibility, and clinical translation. Future directions prioritize fs-PLAL optimization, biohybrid architectures, and multimodal AuNP platforms for precision oncology.
