In the last few decades, the vast potential of nanomaterials for biomedical and healthcare applications has been extensively investigated. Several case studies demonstrated that nanomaterials can offer solutions to the current challenges of raw materials in the biomedical and healthcare fields. This review describes the different nanoparticles and nanostructured material synthesis approaches and presents some emerging biomedical, healthcare, and agro-food applications. This review focuses on various nanomaterial types (e.g., spherical, nanorods, nanotubes, nanosheets, nanofibers, core-shell, and mesoporous) that can be synthesized from different raw materials and their emerging applications in bioimaging, biosensing, drug delivery, tissue engineering, antimicrobial, and agro-foods. Depending on their morphology (e.g., size, aspect ratio, geometry, porosity), nanomaterials can be used as formulation modifiers, moisturizers, nanofillers, additives, membranes, and films. As toxicological assessment depends on sizes and morphologies, stringent regulation is needed from the testing of efficient nanomaterials dosages. The challenges and perspectives for an industrial breakthrough of nanomaterials are related to the optimization of production and processing conditions.

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Review on Nanoparticles and Nanostructured Materials: Bioimaging, Biosensing, Drug Delivery, Tissue Engineering, Antimicrobial, and Agro-Food Applications

2D titanium carbide MXenes as emerging optical biosensing platforms

Water scarcity has become an increasingly complex challenge with the growth of the global population, economic expansion, and climate change, highlighting the demand for advanced water treatment technologies that can provide clean water in a scalable, reliable, affordable, and sustainable manner. Recent advancements on 2D nanomaterials (2DM) open a new pathway for addressing the grand challenge of water treatment owing to their unique structures and superior properties. Emerging 2D nanostructures such as graphene, MoS2, MXene, h-BN, g-C3N4, and black phosphorus have demonstrated an unprecedented surface-to-volume ratio, which promises ultralow material use, ultrafast processing time, and ultrahigh treatment efficiency for water cleaning/monitoring. In this review, we provide a state-of-the-art account on engineered 2D nanomaterials and their applications in emerging water technologies, involving separation, adsorption, photocatalysis, and pollutant detection. The fundamental design strategies of 2DM are discussed with emphasis on their physicochemical properties, underlying mechanism and targeted applications in different scenarios. This review concludes with a perspective on the pressing challenges and emerging opportunities in 2DM-enabled wastewater treatment and water-quality monitoring. This review can help to elaborate the structure–processing–property relationship of 2DM, and aims to guide the design of next-generation 2DM systems for the development of selective, multifunctional, programmable, and even intelligent water technologies. The global significance of clean water for future generations sheds new light and much inspiration in this rising field to enhance the efficiency and affordability of water treatment and secure a global water supply in a growing portion of the world.

Engineered two-dimensional nanomaterials: an emerging paradigm for water purification and monitoring

Two-dimensional MXenes have been extensively investigated in recent years and have resulted in the discovery of more than 30 compositions. The metallic conductivity and pseudocapacitive behavior of MXenes have demonstrated their exciting potential in electrochemical energy storage and conversion, electromagnetic shielding, wearable sensors, and personal thermotherapy. Driven by the surface termination functional groups, versatile chemistry, and outstanding solubility, MXenes have been integrated with various flexible and nanoporous substrates for wearable nanodevice applications. However, the available review mostly focuses on different substrates for multifunctional applications. No review intended for wearable nanodevices with a special focus on the breathability and comfort has been reported to date. In this review, we summarized the synthesis processes and their impact on MXene properties, and the structure–property relationship of MXenes. The current progress in MXene integration processes is comprehensively summarized and analyzed. We explored and evaluated the energy harvesting and storage, electromagnetic shielding, joule heating, as well as strain and pressure sensing applications. A brief overview of humidity and gas sensing of the MXene-based nanostructure is provided. Besides, the current challenges and perspectives in these burgeoning fields are highlighted for the development of wearable nanodevices.

Two-dimensional MXene-based flexible nanostructures for functional nanodevices: a review

Advances and challenges in 2D MXenes: from structures to energy storage and conversions

A simple one-step ultrasonic method was developed for the synthesis of luminescent MnO2 quantum dots (MnO2 QDs) in the presence of cysteine, in which cysteine acted as the exfoliating agent and stabilization ligand. The cysteine-stabilized MnO2 QDs (Cys-MnO2 QDs) possess a fluorescence quantum yield of 4.7%, and the fluorescence intensity of Cys-MnO2 QDs is sensitive to dopamine (DA). The mechanism by which the Cys-MnO2 QDs catalyzed the self-polymerization of DA to form polydopamine nanoparticles (PDA NPs) and caused the fluorescence resonance energy transfer (FRET) between MnO2 QDs and PDA NPs was revealed. The sensing platform displayed a wide detection range (0.1-200 μM) with a low detection limit of 28 nM for the detection of DA. Moreover, the Michael addition/Schiff base reaction between the PDA NPs and cysteine on MnO2 QDs was demonstrated to facilitate the excellent selectivity toward DA detection in the presence of various interferences. This work not only develops a robust method for the preparation of highly luminescent MnO2 QDs but also provides a universal strategy on the basis of surface chemical reaction-induced FRET for the detection of DA with high sensitivity and selectivity, which is promising in the application of clinical diagnosis, drug delivery, and fluorescence-guided cancer therapy.

Self-Catalyzed Surface Reaction-Induced Fluorescence Resonance Energy Transfer on Cysteine-Stabilized MnO2 Quantum Dots for Selective Detection of Dopamine.

An ultrasensitive signal amplification strategy has been developed using Au@Cu-MOF nanocapsules as an electrochemical platform for the determination of glutathione (GSH) based on the signal output ...

Au/Metal–Organic Framework Nanocapsules for Electrochemical Determination of Glutathione

Group IV nanodots (NDs) have gathered considerable attention not only for their easy and low cost of synthesis, large surface area, nice photostability, excellent biocompatibility but for their special nanozyme properties. In this review, group IV NDs including carbon (C), silicon (Si) and germanium (Ge) NDs, are summarized and discussed, with an emphasis on biosensing application. The rational design of the group IV NDs based nanoplatforms to detect various biomarkers via colorimetric, fluorescence, electrochemical, electrochemiluminescence (ECL) and photoelectrochemical (PEC) methods for various biomarkers are thoroughly reviewed. The structure-properties relationship is stated, and some typical detection mechanism also emphasized. The current limitations and future directions of these materials are presented with new insights into the remaining challenges and trends of group IV ND research. It hopefully provides researchers with a distinct perspective on the synthesis of functional group IV NDs with specific properties and construction of biomarker sensors with high selectivity and sensitivity.

Group IV nanodots: Newly emerging properties and application in biomarkers sensing

Titanium carbides (Ti3C2), a new family of two-dimensional (2D) nanomaterials, have attracted extensive attention due to their unique structure and desirable physiochemical properties. Herein, we developed an effective and selective fluorescent turn-on nanosensor for glucose detection based on Ti3C2 nanosheets combined with red-emitting carbon dots (RCDs). The fluorescence intensity of RCDs could be effectively quenched (>96%) by Ti3C2 nanosheets through the inner-filter effect (IFE). In the presence of H2O2, the quenched fluorescence of the RCDs can remarkably recover due to the Ti3C2 nanosheets which were oxidized into Ti(OH)4 by H2O2. Based on H2O2 generated from oxidation of glucose catalyzed by glucose oxidase, the nanosensor can also be exploited for monitoring glucose. Under optimal conditions, a linear relationship between the increased fluorescence intensity of RCDs and the concentration of glucose was established in the range from 0.1 to 20 mM. The detection limit was 50 μM (S/N = 3). The proposed nanosensor also represented excellent selectivity for glucose analysis in biological fluid samples, providing a valuable platform for glucose sensing in clinical diagnostics.

Xiaohua Zhu

Papers

2D titanium carbide MXenes as emerging optical biosensing platforms

Self-Catalyzed Surface Reaction-Induced Fluorescence Resonance Energy Transfer on Cysteine-Stabilized MnO2 Quantum Dots for Selective Detection of Dopamine.

Au/Metal–Organic Framework Nanocapsules for Electrochemical Determination of Glutathione

Group IV nanodots: Newly emerging properties and application in biomarkers sensing

Titanium carbide MXenes combined with red-emitting carbon dots as a unique turn-on fluorescent nanosensor for label-free determination of glucose.