The integration of polymer coatings with metal and metal oxide nanoparticles represents a significant advancement in nanotechnology, enhancing the stability, biocompatibility, and functional versatility of these materials. These enhanced properties make polymer-coated nanoparticles key components in a wide range of applications, including biomedicine, catalysis, environmental remediation, electronics, and energy storage. The unique combination of polymeric materials with metal and metal oxide cores results in hybrid structures with superior performance characteristics, making them highly desirable for various technological innovations. Polymer-coated metal and metal oxide nanoparticles can be synthesized through various methods, such as grafting to, grafting from, grafting through, in situ techniques, and layer-by-layer assembly, each offering distinct control over nanoparticle size, shape, and surface functionality. The distinctive contribution of this review lies in its systematic comparison of polymer-coating synthesis approaches for different metal and metal oxide nanoparticles, revealing how variations in polymer architecture and surface chemistry govern their stability, functionality, and application performance. The aim of this paper is to provide a comprehensive overview of the current state of research on polymer-coated nanoparticles, including metals such as gold, silver, copper, platinum, and palladium, as well as metal oxides like iron oxide, titanium dioxide, zinc oxide, and aluminum oxide. This review highlights their design strategies, synthesis methods, characterization approaches, and diverse emerging applications, including biomedicine (e.g., targeted drug delivery, gene delivery, bone tissue regeneration, imaging, antimicrobials, and therapeutic interventions), environmental remediation (e.g., antibacterials and sensors), catalysis, electronics, and energy conversion.

Magnetic iron oxide nanoparticles (MIONPs) represent a versatile magnetic nanoparticle (NP) system with considerable, yet underexplored, potential in diverse applications, particularly in emerging biomedical fields such as magnetic resonance imaging, magnetic hyperthermia, targeted drug delivery, and biosensing. The successful translation of MIONPs into these applications requires reproducible synthesis methods and precise control over particle uniformity in terms of size, shape, and composition. However, reproducibility in nanoparticle synthesis remains a persistent challenge, limiting the ability of researchers to replicate results and integrate MIONPs into application-oriented studies. In recent years, substantial efforts have been directed toward elucidating synthesis mechanisms and improving both reproducibility and particle uniformity, enabling notable advances in the biomedical deployment of MIONPs. This review summarizes progress in the synthesis of MIONPs, with emphasis on three widely employed precursors: iron oleate, iron acetylacetonate, and iron pentacarbonyl. The discussion focuses on key findings in NP synthesis, relevant chemical aspects, and the magnetic properties of MIONPs, which are critical for optimizing their functional performance. By consolidating recent advances, this review aims to provide a reliable framework for the preparation of high-quality MIONPs and to support their effective use in specific biomedical applications.

Recent advancements in nanotechnology and materials science have enabled the development of magnetic photocatalysts with improved efficiency, stability, and reusability, offering a promising approach for wastewater treatment. The integration of magnetic nanoparticles (MNPs) into photocatalytic processes has gained significant attention as a sustainable method for addressing emerging pollutants—such as antibiotics and pharmaceutical compounds—which pose environmental and public health risks, including the proliferation of antibiotic resistance. Surface modification techniques, specifically applied to MNPs, are employed to enhance their photocatalytic performance by improving surface reactivity, reducing nanoparticle agglomeration, and increasing photocatalytic activity under both visible and ultraviolet (UV) light irradiation. These modifications also facilitate the selective adsorption and degradation of target contaminants. Importantly, the modified nanoparticles retain their magnetic properties, allowing for facile separation and reuse in multiple treatment cycles via external magnetic fields. This review provides a comprehensive overview of recent developments in surface-modified MNPs for wastewater treatment, with a focus on their physicochemical properties, surface modification strategies, and effectiveness in the removal of antibiotics from aqueous environments. Furthermore, the review discusses advantages over conventional treatment methods, current limitations, and future research directions, emphasizing the potential of this technology for sustainable and efficient water purification.

Nanomaterial-based biosensors have advanced analytical methodologies by enhancing signal transduction, interfacial reactivity, and molecular recognition across diverse sensing platforms. In parallel, the diversity of nanomaterial compositions, architectures, and interfacial designs has expanded the range of available sensing strategies and performance outcomes. This review addresses limitations through a structure–property–function framework that links nanomaterial characteristics to sensing behavior, performance determinants, and application-specific requirements. Within this framework, nanomaterials are classified according to their dominant functional roles in biosensing, including plasmonic, electroactive, fluorescent and quantum-confined, porous, and hybrid architectures. The influence of morphology, surface chemistry, conductivity, and interfacial design on electrochemical, optical, and hybrid transduction mechanisms is critically examined, and key performance parameters, including sensitivity, selectivity, limit of detection, response time, stability, and reproducibility, are discussed in relation to material properties and sensing configuration. Recent advances in clinical biomarker detection, pathogen and nucleic acid analysis, and environmental and food safety monitoring are also evaluated to illustrate how nanomaterial design is tailored to different analytical contexts. Current limitations related to reproducibility, interface engineering, long-term stability, and scalable device integration are highlighted, together with future directions for the rational development of robust and application-oriented biosensor platforms.