Synthesis,Optical Properties,and Sensing Applications of Gold Nanodots

In this Personal Account, we briefly address our journey in developing photoluminescent nanomaterials for sensing purposes, with a focus on gold nanodots (Au NDs). Their synthetic strategies, optical properties, and sensing applications are emphasized. The Au NDs can be simply prepared from the etching of small‐sized Au nanoparticles (<3 nm in diameter) by thiol compounds such as 11‐mercaptoundecanoic acid under alkaline conditions. This simple approach allows the preparation of various functional Au NDs by choosing different thiol compounds as etching agents. Since the optical properties of Au NDs are highly dependent on the core and shell of each Au ND, the selection of etching reagents is important. Over the years we have developed various sensing systems using Au NDs for the detection of metal ions, anions, and proteins, based on analyte‐induced photoluminescence quenching/enhancement of Au NDs as a result of changes in their oxidation state, shell composition, and structure.     

Nanomaterials and lab-on-a-chip technologies

Lab-on-a-chip (LOC) platforms have become important tools for sample analysis and treatment with interest for DNA, protein and cells studies or diagnostics due to benefits such as the reduced sample volume, low cost, portability and the possibility to build new analytical devices or be integrated into conventional ones. These platforms have advantages of a wide set of nanomaterials (NM) (i.e. nanoparticles, quantum dots, nanowires, graphene etc.) and offer excellent improvement in properties for many applications (i.e. detectors sensitivity enhancement, biolabelling capability along with other in-chip applications related to the specificities of the variety of nanomaterials with optical, electrical and/or mechanical properties). This review covers the last trends in the use of nanomaterials in microfluidic systems and the related advantages in analytical and bioanalytical applications. In addition to the applications of nanomaterials in LOCs, we also discuss the employment of such devices for the production and characterization of nanomaterials. Both framed platforms, NMs based LOCs and LOCs for NMs production and characterization, represent promising alternatives to generate new nanotechnology tools for point-of-care diagnostics, drug delivery and nanotoxicology applications.     

Nanomaterials in Protein Sample Preparation

Protein sample preparation is the most critical step in protein analysis of complex samples and is constituted by tedious, time-consuming, and difficult-to-automate steps that usually involve the use of high volumes of solvents. In recent years, novel extraction or digestion nanomaterials (NMs) have been developed aiming to overcome these drawbacks. In this review, we have grouped the recent works related to the development of new NMs and their applications to the extraction, enrichment/purification, and digestion of proteins. This paper evaluates the role of different kinds of NMs in each step of protein sample preparation focusing on the type of established interaction between the protein and the nanomaterial, their sensitivity and selectivity, their adsorption capacity, and the advantages that they bring in relation to time, efficiency, or reusability.     

Chemistry of two-dimensional MXene nanosheets in theranostic nanomedicine

Transition metal carbide,carbonitride and nitride MXenes,as the emerging two-dimensional(2D)nanomaterials,have aroused burgeoning research interest in a broad range of applications ranging from energy conversion to biomedicines attributing to their distinctive planar nanostructure,physiochemical properties and biological effects.They are featured with fascinating electronic,optical,magnetic,mechanical and thermal properties,which exert significant roles in biomedical applications of 2D MXenes.In this review,we briefly summarize the recent research progress of 2D MXenes and highlight their intrinsic chemistry in theranostic nanomedicines,focusing on the synthetic chemistry for MXenes construction,surface chemistry for surface engineering,physiochemical property for theranostic application and biological chemistry for biosafety evaluation.Furthermore,based on the current achieve ments on MXenes,their potential research directio n,critical challenges and future development in biomedicine are also discussed.It is highly expected that 2D MXene-based nanosystems would have a broad application prospect in theranostic biomedicine provided the current facing critical issues and challenges are adequately solved.     

From Prebiotic Chemistry to Supramolecular Biomedical Materials: Exploring the Properties of Self-Assembling Nucleobase-Containing Peptides

Peptides and their synthetic analogs are a class of molecules with enormous relevance as therapeutics for their ability to interact with biomacromolecules like nucleic acids and proteins, potentially interfering with biological pathways often involved in the onset and progression of pathologies of high social impact. Nucleobase-bearing peptides (nucleopeptides) and pseudopeptides (PNAs) offer further interesting possibilities related to their nucleobase-decorated nature for diagnostic and therapeutic applications, thanks to their reported ability to target complementary DNA and RNA strands. In addition, these chimeric compounds are endowed with intriguing self-assembling properties, which are at the heart of their investigation as self-replicating materials in prebiotic chemistry, as well as their application as constituents of innovative drug delivery systems and, more generally, as novel nanomaterials to be employed in biomedicine. Herein we describe the properties of nucleopeptides, PNAs and related supramolecular systems, and summarize some of the most relevant applications of these systems.     

Trends in the sample preparation and analysis of nanomaterials as environmental contaminants

Much research on the use of nanomaterials in different applications is being conducted in areas such as water treatment, catalysis, oil processing, medicine, food, sensors, energy storage, building materials, constructions, and others. Nanoparticles are ultra-small particles with exceptional properties, but some nanoparticles and nanomaterials may exhibit harmful properties when leaked into the environment. Due to the lack of analytical methods for the detection and analysis of nanoparticles in complex matrices, not much is known about the potential risks associated with nanomaterials. Therefore, more knowledge is needed of the sampling and analysis of nanomaterials (NMs) as environmental contaminants. This review is undertaken to identify and assess key characteristics in potential sampling and analysis methods for identifying and quantifying the occurrence of NMs in numerous types of environmental media. To select suitable sampling and analysis methods, information on NM sources and transformation in environmental media is essential and thus is also discussed. This provides more information about the negative impacts of NMs on the environment. Challenges and future perspectives on the determination of NMs are also discussed.     

Emerging Two-Dimensional Nanomaterials for Cancer Therapy

Two-dimensional (2D) nanomaterials have drawn tremendous attention due to their unique physicochemical properties and promising applications in the fields of electronics, energy storage, and catalysis. Recently, the biomedicine community has gradually started to recognize the great potential of these nanostructured materials for biomedical applications – in particular those related to cancer therapy. In this review, we provide a brief overview of a few representative 2D nanomaterials, discuss their preparation strategies and physicochemical properties, and highlight their applications in cancer nanomedicine. We expect that this review will shed some light on the new opportunities associated with 2D nanomaterials for biomedical research.     

金纳米簇的制备及其在生物医学中的应用

金纳米簇由几个到几十个金原子组成,具有尺寸小、荧光性能好、无毒等优点,被广泛应用于生物医学领域。本文介绍了包括模板法,刻蚀法,可逆相转移法和动力学控制法等金纳米簇的主要制备方法,并综述了金纳米簇在生物医学上的主要应用,包括生物检测、荧光成像和药物控释。     

Preparation of Photocatalytic Au–Ag2Te Nanomaterials

A facile approach has been developed for the preparation of various morphologies of Au–Ag₂Te nanomaterials (NMs) that exhibit strong photocatalytic activity. Te NMs (nanowires, nanopencils, and nanorice) were prepared from TeO₂ in the presence of various concentrations (16, 8, and 4 M ) of a reducing agent (N₂H₄) at different temperatures (25 and 60 °C). These three Te NMs were then used to prepare Au–Ag₂Te NMs by spontaneous redox reactions with Au³⁺ and Ag⁺ ions sequentially. The Au–Ag₂Te nanopencils exhibit the highest activity toward degradation of methylene blue and formation of active hydroxyl radicals on solar irradiation, mainly because they absorb light in the visible region most strongly. All three differently shaped Au–Ag₂Te NMs (10 μg mL^?1) provide a death rate of Escherichia coli greater than 80 % within 60 min, which is higher than that of 51 % for commercial TiO₂ nanoparticles (100 μg mL^?1). Under light irradiation, the Au NPs in Au–Ag₂Te NMs enhance the overall photo‐oxidation ability of Ag₂Te NMs through faster charge separation because of good contact between Ag₂Te and Au segments. With high antibacterial activity and low toxicity toward normal cells, the Au–Ag₂Te NMs hold great potential for use as efficient antibacterial agents.     

量子点在生物检测中的应用

过去十几年里,量子点从材料科学到生命科学、从基础研究到实际应用都开展了广泛的研究。 量子点在生物成像、光治疗、药物/基因转运、太阳能电池等领域均具有广泛的应用。 通过调节量子点的表面性质,实现量子点与细胞相互作用的可控性是一个关键的问题。 伴随着量子点潜在毒性问题的产生,纳米毒性成为纳米材料安全性评估的重要指标,并且受到科学家们的高度关注。 本文综述了量子点的特性、细胞生物学应用及在生物医药领域相关的细胞毒性研究,并展望了量子点的未来发展趋势。     

The golden age: gold nanoparticles for biomedicine

Gold nanoparticles have been used in biomedical applications since their first colloidal syntheses more than three centuries ago. However, over the past two decades, their beautiful colors and unique electronic properties have also attracted tremendous attention due to their historical applications in art and ancient medicine and current applications in enhanced optoelectronics and photovoltaics. In spite of their modest alchemical beginnings, gold nanoparticles exhibit physical properties that are truly different from both small molecules and bulk materials, as well as from other nanoscale particles. Their unique combination of properties is just beginning to be fully realized in range of medical diagnostic and therapeutic applications. This critical review will provide insights into the design, synthesis, functionalization, and applications of these artificial molecules in biomedicine and discuss their tailored interactions with biological systems to achieve improved patient health. Further, we provide a survey of the rapidly expanding body of literature on this topic and argue that gold nanotechnology-enabled biomedicine is not simply an act of 'gilding the (nanomedicinal) lily', but that a new 'Golden Age' of biomedical nanotechnology is truly upon us. Moving forward, the most challenging nanoscience ahead of us will be to find new chemical and physical methods of functionalizing gold nanoparticles with compounds that can promote efficient binding, clearance, and biocompatibility and to assess their safety to other biological systems and their long-term term effects on human health and reproduction (472 references).     

Water-Dispersible Gold Nanoclusters: Synthesis Strategies,Optical Properties,and Biological Applications

Atomically precise gold nanoclusters (AuNCs) are an emerging class of quantum-sized nanomaterials. Intrinsic discrete electronic energy levels have endowed them with fascinating electronic and optical properties. They have been widely applied in the fields of optoelectronics, photovoltaics, catalysis, biochemical sensing, bio-imaging, and therapeutics. Nevertheless, most AuNCs are synthesized in organic solvents and do not disperse in aqueous solutions; this restricts their biological applications. In this review, we focus on the recent progress in the preparation of water-dispersible AuNCs and their biological applications. We first review different methods of synthesis, including direct synthesis from hydrophilic templates and indirect phase transfer of hydrophobic AuNCs. We then discuss their photophysical properties, such as emission enhancement and fluorescence lifetimes. Next, we summarize their latest applications in the fields of biosensing, biolabeling, and bioimaging. Finally, we outline the challenges and potential for the future development of these AuNCs.     

Probing the interaction at nano-bio interface using synchrotron radiation-based analytical techniques

Understanding the interactions of nanomaterials(NMs) with biomolecules, organelles, cells, and organic tissues at the nano-bio interface can offer important information for their uptake, distribution, translocation, metabolism and degradation in vitro and in vivo, which can help to precisely tune and design "smart" NMs for biomedical applications. However, probing the interactions at the nano-bio interface, which generally requires dedicated analytical methods and tools, is remarkably complicated due to the dynamically changed nature of the nano-bio interface. Because of the advantages of high spatial resolution, high sensitivity, excellent accuracy, low matrix effects and non-destructiveness, synchrotron radiation(SR)-based analytical techniques have become extremely valuable tools. Herein, we present a comprehensive overview of SR-based techniques for the visualized study of NMs at cellular and subcellular interfaces and their transformation in vitro; the exploration of biodistribution, translocation, metabolism and degradation of NMs in vivo; and clarification of the molecular mechanisms of NMs' reactions with biomolecules. Rapid development of advanced light source means that in situ, real-time analysis of NMs at the nano-bio interface will be achieved.     

Localized surface plasmon resonance properties and biomedical applications of copper selenide nanomaterials

Nanomaterials with localized surface plasmon resonance (LSPR) locating in the near-infrared region have broad application prospects in the field of biomedicine. However, the biggest problem that limits the biomedical application of such nanomaterials lies in two aspects: First, the potential long-term in vivo toxicity caused by the metabolism of many nanomaterials with LSPR effect; Second, most of current nanomaterials with LSPR effect are difficult to achieve LSPR wavelength tunability in the near-infrared region to adapt to different biomedical applications. Copper selenide nanomaterials are composed of selenium and copper, which are necessary nutrient elements for human life. Because of the active and flexible chemical properties of selenium and copper, copper selenide nanomaterials can not only be effectively degraded and utilized in human body, but also be endowed with various physicochemical properties by chemical modification or doping. Recently, copper selenide nanomaterials have shown unique properties such as LSPR in the near-infrared region, making them attractive for near-infrared thermal ablation, photoacoustic imaging, disease marker detection, multimode imaging, and so on. Currently, to the best of our knowledge, there is no review on the LSPR properties of copper selenide nanomaterials and its biomedical applications. This review first discusses the relationship between the physicochemical properties and the LSPR of copper selenide nanomaterials and then summarizes the latest progress in the application of copper selenide nanomaterials in biological detection, diagnosis, and treatment of diseases. In addition, the advantages, and prospects of copper selenide nanomaterials in biomedicine are also highlighted.     

Biogenic Sulfur-Based Chalcogenide Nanocrystals: Methods of Fabrication,Mechanistic Aspects,and Bio-Applications

Bio-nanotechnology has emerged as an efficient and competitive methodology for the production of added-value nanomaterials (NMs). This review article gathers knowledge gleaned from the literature regarding the biosynthesis of sulfur-based chalcogenide nanoparticles (S-NPs), such as CdS, ZnS and PbS NPs, using various biological resources, namely bacteria, fungi including yeast, algae, plant extracts, single biomolecules, and viruses. In addition, this work sheds light onto the hypothetical mechanistic aspects, and discusses the impact of varying the experimental parameters, such as the employed bio-entity, time, pH, and biomass concentration, on the obtained S-NPs and, consequently, on their properties. Furthermore, various bio-applications of these NMs are described. Finally, key elements regarding the whole process are summed up and some hints are provided to overcome encountered bottlenecks towards the improved and scalable production of biogenic S-NPs.     

Chirality at nanoscale for bioscience

In the rapidly expanding fields of nanoscience and nanotechnology, there is considerable interest in chiral nanomaterials, which are endowed with unusually strong circular dichroism. In this review, we summarize the principles of organization underlying chiral nanomaterials and generalize the recent advances in the main strategies used to fabricate these nanoparticles for bioscience applications. The creation of chirality from nanoscale building blocks has been investigated both experimentally and theoretically, and the tunability of chirality using external fields, such as light and magnetic fields, has allowed the optical activity of these materials to be controlled and their properties understood. Therefore, the specific recognition and potential applications of chiral materials in bioscience are discussed. The effects of the chirality of nanostructures on biological systems have been exploited to sense and cut molecules, for therapeutic applications, and so on. In the final part of this review, we examine the future perspectives for chiral nanomaterials in bioscience and the challenges posed by them.

In this review, we summarize the principles of fabrication on chiral nanomaterials and generalize the recent achievements for the bioscience applications.     

Au25纳米团簇合成与应用研究进展

综述了新型金属纳米材料Au25纳米团簇的合成机理和合成工艺改进,结合Au纳米团簇荧光作用机理说明其特有的荧光特性,利用Au纳米团簇荧光性质在离子检测、生物小分子检测、蛋白质检测和生物成像方面的应用,为Au纳米团簇的研究提供参考。     

Quantum dot-based energy transfer: perspectives and potential for applications in photodynamic therapy

Quantum dots have emerged as an important class of material that offers great promise to a diverse range of applications ranging from energy conversion to biomedicine. Here, we review the potential of using quantum dots and quantum dot conjugates as sensitizers for photodynamic therapy (PDT). The photophysics of singlet oxygen generation in relation to quantum dot-based energy transfer is discussed and the possibility of using quantum dots as photosensitizer in PDT is assessed, including their current limitations to applications in biological systems. The biggest advantage of quantum dots over molecular photosensitizers that comes into perspective is their tunable optical properties and surface chemistries. Recent developments in the preparation and photophysical characterization of quantum dot energy transfer processes are also presented in this review, to provide insights on the future direction of quantum dot-based photosensitization studies from the viewpoint of our ongoing research.     

Stable isotope labeling of nanomaterials for biosafety evaluation and drug development

Quantitative information, such as environmental migration, absorption, biodistribution, biotransformation, and elimination, is fundamental and essential for the nanosafety evaluations of nanomaterials. Due to the complexity of biological and environmental systems, it is challenging to develop quantitative approaches and tools that could characterize intrinsic behaviors of nanomaterials in the organisms. The isotopic tracers are ideal candidates to tune the physical properties of nanomaterials while preserving their chemical properties. In this review article, we summarized the stable isotope labeling methods of nanomaterials for evaluating their environmental and biological effects. The skeleton labeling protocols of carbon nanomaterials and metal/metal oxide nanoparticles were introduced. The advantages and disadvantages of stable isotope labeling were discussed in comparison with other quantitative methods for nanomaterials. The quantitative information of nanomaterials in environmental and biological systems was summarized along with the biosafety data. The benefits for drug development of nanomedicine were analyzed based on the targeting effects, persistent accumulation, and safety. Finally, the challenges and future perspectives of stable isotope labeling in nanoscience and nanotechnology were discussed.     

Chemical Functionalization of Nanodiamonds: Opportunities and Challenges Ahead

Nanodiamond(ND)‐based technologies are flourishing in a wide variety of fields spanning from electronics and optics to biomedicine. NDs are considered a family of nanomaterials with an sp³ carbon core and a variety of sizes, shapes, and surfaces. They show interesting physicochemical properties such as hardness, stiffness, and chemical stability. Additionally, they can undergo ad‐hoc core and surface functionalization, which tailors them for the desired applications. Noteworthy, the properties of NDs and their surface chemistry are highly dependent on the synthetic method used to prepare them. In this Minireview, we describe the preparation of NDs from the materials‐chemistry viewpoint. The different methodologies of synthesis, purification, and surface functionalization as well as biomedical applications are critically discussed. New synthetic approaches as well as limits and obstacles of NDs are presented and analyzed.