Controllable synthesis and biomedical applications of silver nanomaterials

Silver nanomaterials have lots of peculiar and exciting physical and chemical properties that are different from massive silver, so the synthesis and applications of silver nanomaterials have attracted a great deal of attention in the last decade. Currently, all kinds of silver nanomaterials having different shapes and sizes have been synthesized by many ingenious methods, and silver nanomaterials have exhibited extensive application prospects in many fields especially in biomedical aspect. In this article, the controllable synthesis of silver nanomaterials including nanorods, nanowires, nanotubes, nanoprisms, nanoplates, nanodisks, nanospheres, and nanopolyhedrons, etc. are reviewed. Silver nanomaterials are most utilized in the form of nanoparticles, so the main biomedical applications of silver nanoparticles, such as antibacterial and antiviral applications, antitumor applications, biosensors and biological labels, optical imaging and imaging intensifier, are discussed. Although antibacterial applications are still the most important aspects of silver nanomaterials at present, antitumor, optical sensors and imaging applications of silver nanomaterials have also shown good potential perspectives. More biomedical applications of silver nanomaterials still need to be exploited for the future, and the biological safety of silver nanomaterials also should be paid enough attention before their practical applications.     

Stimuli‐Responsive Optical Nanomaterials

Responsive optical nanomaterials that can sense and translate various external stimuli into optical signals, in the forms of observable changes in appearance and variations in spectral line shapes, are among the most active research topics in nanooptics. They are intensively exploited within the regimes of the four classic optical phenomena—diffraction in photonic crystals, absorption of plasmonic nanostructures, as well as color‐switching systems, refraction of assembled birefringent nanostructures, and emission of photoluminescent nanomaterials and molecules. Herein, a comprehensive review of these research activities regarding the fundamental principles and practical strategies is provided. Starting with an overview of their substantial developments during the latest three decades, each subtopic discussion is led with fundamental theories that delineate the correlation between nanostructures and optical properties and the delicate research strategies are elaborated with specific attention focused on working principles and optical performances. The unique advantages and inherent limitations of each responsive optical nanoscale platform are summarized, accompanied by empirical criteria that should be met and perspectives on research opportunities where the developments of next‐generation responsive optical nanomaterials might be directed.     

A Safe‐by‐Design Strategy towards Safer Nanomaterials in Nanomedicines

The marriage of nanotechnology and medicine offers new opportunities to fight against human diseases. Benefiting from their unique optical, thermal, magnetic, or redox properties, a wide range of nanomaterials have shown potential in applications such as diagnosis, drug delivery, or tissue repair and regeneration. Despite the considerable success achieved over the past decades, the newly emerging nanomedicines still suffer from an incomplete understanding of their safety risks, and of the relationships between their physicochemical characteristics and safety profiles. Herein, the most important categories of nanomaterials with clinical potential and their toxicological mechanisms are summarized, and then, based on this available information, an overview of the principles in developing safe‐by‐design nanomaterials for medical applications and of the recent progress in this field is provided. These principles may serve as a starting point to guide the development of more effective safe‐by‐design strategies and to help identify the major knowledge and skill gaps.     

Gold Nanomaterials in Consumer Cosmetics Nanoproducts: Analyses,Characterization, and Dermal Safety Assessment

Establishment of analytical methods of engineered nanomaterials in consumer products for their human and environmental risk assessment becomes urgent for both academic and industrial needs. Owing to the difficulties and challenges around nanomaterials in complex media, proper chemical separation and biological assays of nanomaterials from nanoproducts needs to be firstly developed. Herein, a facile and rapid method to separate and analyze gold nanomaterials in cosmetics is reported. Gold nanomaterials are successfully separated from different facial or eye creams and their physiochemical properties are analyzed by quantitative and qualitative state‐of‐the art techniques with high sensitivity or high spatial resolution. In turn, a protocol including quantification of gold by inductively coupled plasma mass spectrometry and thorough characterization of morphology, size distribution, and surface property by electron microscopes, atomic force microscope, and X‐ray photoelectron spectroscope is developed. Subsequently, the preliminary toxicity assessment indicates that gold nanomaterials in cosmetic creams have no observable toxicity to human keratinocytes even after 24 h exposure up to a concentration of 200 μg mL^?1. The environmental scanning electron microscope reveals that gold nanomaterials are mostly attached on the cell membrane. Thus, the present study provides a full analysis protocol for toxicity assessment of gold nanomaterials in consumer products (cosmetic creams).     

The correlation among morphology,oxygen vacancies and properties of ZnO nanoflowers

Despite numerous reports have investigated the effect of morphology on the properties of nanomaterials, its role in tuning nanomaterials properties is still not clear to date. This work introduces a unique attempt to explore the correlation among morphology, surface defects (oxygen vacancies), and properties of nanomaterials. To achieve this task, three different morphologies of ZnO nanoflowers were prepared via hydrothermal method by varying the concentration of diethylamine. It was observed that a change in ZnO nanoflowers morphology results in changes in their optical, photocatalytic, and antibacterial properties. Photoluminescence and X-ray photoelectron spectroscopy analyses reveal the presence of oxygen vacancies (V_O) in ZnO nanoflowers with a concentration varies with respect to morphology. V_O concentration plays a key role in tuning ZnO band gap and the concentration of reactive oxygen species and thereby tuning optical, photocatalytic, and antibacterial properties of ZnO nanoflowers. Our results suggest that V_O concentration, morphology, and properties of ZnO nanoflowers are correlated.     

Nanomaterial Patterning in 3D Printing

The synergistic integration of nanomaterials with 3D printing technologies can enable the creation of architecture and devices with an unprecedented level of functional integration. In particular, a multiscale 3D printing approach can seamlessly interweave nanomaterials with diverse classes of materials to impart, program, or modulate a wide range of functional properties in an otherwise passive 3D printed object. However, achieving such multiscale integration is challenging as it requires the ability to pattern, organize, or assemble nanomaterials in a 3D printing process. This review highlights the latest advances in the integration of nanomaterials with 3D printing, achieved by leveraging mechanical, electrical, magnetic, optical, or thermal phenomena. Ultimately, it is envisioned that such approaches can enable the creation of multifunctional constructs and devices that cannot be fabricated with conventional manufacturing approaches.     

Rational Design of Functional Peptide–Gold Hybrid Nanomaterials for Molecular Interactions

Gold nanoparticles (AuNPs) have been extensively used for decades in biosensing-related development due to outstanding optical properties. Peptides, as newly realized functional biomolecules, are promising candidates of replacing antibodies, receptors, and substrates for specific molecular interactions. Both peptides and AuNPs are robust and easily synthesized at relatively low cost. Hence, peptide–AuNP-based bio-nano-technological approaches have drawn increasing interest, especially in the field of molecular targeting, cell imaging, drug delivery, and therapy. Many excellent works in these areas have been reported: demonstrating novel ideas, exploring new targets, and facilitating advanced diagnostic and therapeutic technologies. Importantly, some of them also have been employed to address real practical problems, especially in remote and less privileged areas. This contribution focuses on the application of peptide–gold hybrid nanomaterials for various molecular interactions, especially in biosensing/diagnostics and cell targeting/imaging, as well as for the development of highly active antimicrobial/antifouling coating strategies. Rationally designed peptide–gold nanomaterials with functional properties are discussed along with future challenges and opportunities.     

Second Near-Infrared Plasmonic Nanomaterials for Photoacoustic Imaging and Photothermal Therapy

Photoacoustic imaging (PAI) and imaging-guided photothermal therapy (PTT) in the second near-infrared window (NIR-II, 1000–1700 nm) have received increasing attention owing to their advantages of greater penetration depth and higher signal-to-noise ratio. Plasmonic nanomaterials with tunable optical properties and strong light absorption provide an alternative to dye molecules, showing great prospects for phototheranostic applications. In this review, the research progress in principally modulating the optical properties of plasmonic nanomaterials, especially affecting parameters such as size, morphology, and surface chemical modification, is introduced. The commonly used plasmonic nanomaterials in the NIR-II window, including noble metals, semiconductors, and heterostructures, are then summarized. In addition, the biomedical applications of these NIR-II plasmonic nanomaterials for PAI and PTT in phototheranostics are highlighted. Finally, the perspectives and challenges for advancing plasmonic nanomaterials for practical use and clinical translation are discussed.     

Cytotoxicity of BSA‐Stabilized Gold Nanoclusters: In Vitro and In Vivo Study

Gold nanoclusters (Au NCs) are one of the most promising fluorescent nanomaterials for bioimaging, targeting, and cancer therapy due to their tunable optical properties, yet their biocompatibility still remains unclear. Herein, the cytotoxicity of bovine serum albumin (BSA)‐stabilized Au NCs is studied by using three tumor cell lines and two normal cell lines. The results indicate that Au NCs induce the decline of cell viabilities of different cell lines to varying degrees in a dose‐ and time‐dependent manner, and umbilical vein endothelial cells which had a higher intake of Au NCs than melanoma cells show more toxicity. Addition of free BSA to BSA‐Au NCs solutions can relieve the cytotoxicity, implying that BSA can prevent cell damage. Moreover, Au NCs increase intracellular reactive oxygen species (ROS) production, further causing cell apoptosis. Furthermore, N‐acetylcysteine, a ROS scavenger, partially reverses Au NCs‐induced cell apoptosis and cytotoxicity, indicating that ROS might be one of the primary reasons for the toxicity of BSA‐Au NCs. Surprisingly, Au NCs with concentrations of 5 and 20 nM significantly inhibit tumor growth in the xenograft mice model of human liver cancer, which might provide a new avenue for the design of anti‐cancer drug delivery vehicles.     

2D Nanomaterials for Cancer Theranostic Applications

2D nanomaterials with unique nanosheet structures, large surface areas, and extraordinary physicochemical properties have attracted tremendous interest. In the area of nanomedicine, research on graphene and its derivatives for diverse biomedical applications began as early as 2008. Since then, many other types of 2D nanomaterials, including transition metal dichalcogenides, transition metal carbides, nitrides and carbonitrides, black phosphorus nanosheets, layered double hydroxides, and metal–organic framework nanosheets, have been explored in the area of nanomedicine over the past decade. In particular, a large surface area makes 2D nanomaterials highly efficient drug delivery nanoplatforms. The unique optical and/or X-ray attenuation properties of 2D nanomaterials can be harnessed for phototherapy or radiotherapy of cancer. Furthermore, by integrating 2D nanomaterials with other functional nanoparticles or utilizing their inherent physical properties, 2D nanomaterials may also be engineered as nanoprobes for multimodal imaging of tumors. 2D nanomaterials have shown substantial potential for cancer theranostics. Herein, the latest progress in the development of 2D nanomaterials for cancer theranostic applications is summarized. Current challenges and future perspectives of 2D nanomaterials applied in nanomedicine are also discussed.     

Effect of preparation methods and optical band gap of ZnO nanomaterials on photodegradation studies

Improving of photo-oxidative efficiency of ZnO has become of importance to meet the requirements of environmental protection. In this research, ZnO nanomaterials prepared by three different methods (thermal decomposition, precipitation and sol-gel-combustion using metal nitrate and different fuels (urea, oxalic acid and citric acid)). Various molar ratios of citric acid to salt used as variable parameter (0.50, 0.75, 1.00, 1.25, and 1.50). These nanomaterials were characterized by studying their structural, morphological, surface and optical properties. The photocatalytic activity was evaluated by photocatalytic degradation of Remazol Red RB-133 (RR) under UV-light irradiation. The obtained results showed that the photocatalytic efficiency was affected by preparation method, type and ratio of fuel to salt. The optimum is a gel precursor containing zinc nitrate and citric acid prepared in the molar ratio of 1. The highly active nanomaterial was applied for photocatalytic degradation of mixtures of two dyes – (RR) and Methylene Blue (MB).     

Silver nanoparticles preferentially reduced on PEG-grafted glass surfaces for SERS applications

Silver nanomaterials have been extensively investigated due to their unique optical and biological properties. Surface plasmons and scattering phenomena occurring on silver nanostructures can provide useful analytical or sensor platform. Here, we present silver nanoparticles preferentially reduced on polyethylene glycol (PEG)-grafted glass surfaces for application to surface-enhanced Raman scattering (SERS). Uniform silver nanoparticles of ∼50 nm size were easily generated by dipping the PEG-grafted glass surfaces in silver salt solution at room temperature without any additional reducing agent. The silver nanoparticles generated on the PEG-grafted surfaces were confirmed by AFM and FE-SEM analysis.     

Development of nanotechnology for advancement and application in wound healing: a review

Wound healing is a series of different dynamic and complex phenomena. Many studies have been carried out based on the type and severity of wounds. However, to recover wounds faster there are no suitable drugs available, which are highly stable, less expensive as well as has no side effects. Nanomaterials have been proven to be the most promising agent for faster wound healing among all the other wound healing materials. This review briefly discusses the recent developments of wound healing by nanotechnology, their applicability and advantages. Nanomaterials have unique physicochemical, optical, and biological properties. Some of them can be directly applied for wound healing or some of them can be incorporated into scaffolds to create hydrogel matrix or nanocomposites, which promote wound healing through their antimicrobial, as well as selective anti‐ and pro‐inflammatory, and proangiogenic properties. Owing to their high surface area to volume ratio, nanomaterials have not only been used for drug delivery vectors but also can affect wound healing by influencing collagen deposition and realignment and provide approaches for skin tissue regeneration.Inspec keywords: skin, wounds, cellular biophysics, drug delivery systems, tissue engineering, hydrogels, nanocomposites, proteins, nanomedicineOther keywords: wound healing materials, nanomaterials, nanotechnology, proangiogenic properties, proinflammatory properties, collagen deposition, drug delivery vectors, skin tissue regeneration     

Nucleic acid based polymer and nanoparticle conjugates: Synthesis,properties and applications

Nucleic acid based fabrication of nanomaterials has fascinated scientists since the past two decades and exciting challenges have been surmounted. Recently, nucleic acid is successfully combined with other nanometre-scale entities, sometimes by modifying with chemical functional groups, to obtain a wide range of nanomaterials which in certain cases have been characterized with atomic level precision. These nanomaterials are highly focused due to their new physico-chemical properties, which confer several advantages in multi-disciplinary field of research leading to advanced technologies. This review highlights the systematic advances in the synthesis, properties (optical and electronic) and versatile applications of nucleic acid based nano-biomaterials produced from polymer and metal or semiconductor nanoparticles.     

Quantification of nanoscale density fluctuations using electron microscopy: Light-localization properties of biological cells

We report a study of the nanoscale mass-density fluctuations of heterogeneous optical dielectric media, including nanomaterials and biological cells, by quantifying their nanoscale light-localization properties. Transmission electron microscope images of the media are used to construct corresponding effective disordered optical lattices. Light-localization properties are studied by the statistical analysis of the inverse participation ratio (IPR) of the localized eigenfunctions of these optical lattices at the nanoscale. We validated IPR analysis using nanomaterials as models of disordered systems fabricated from dielectric nanoparticles. As an example, we then applied such analysis to distinguish between cells with different degrees of aggressive malignancy.     

金纳米颗粒在疾病诊断和食品检测领域的研究进展

纳米科技的发展使纳米在各个领域得到了广泛的应用。由于金纳米颗粒具有较高的摩尔吸光系数和特殊的光学、电学、磁学性质,因此它在化学、生物传感、疾病诊断和食品检测等领域的应用取得了突出进展。综述了最近几年金纳米颗粒在疾病诊断和食品检测领域的最新研究进展,特别介绍了国家纳米科学中心近期的研究结果,他们重点研发了可控功能化纳米材料的合成和应用,构建了便携式、高灵敏度的生物化学分析方法系列,为HIV和阿尔茨海默等重大疾病的诊断提供了新方法。讨论了金纳米颗粒具有的优势及存在的问题,并对其未来的发展进行了展望。     

Surface-engineered gold nanorods: promising DNA vaccine adjuvant for HIV-1 treatment

With the intense international response to the AIDS pandemic, HIV vaccines have been extensively investigated but have failed due to issues of safety or efficacy in humans. Adjuvants for HIV/AIDS vaccines are under intense research but a rational design approach is still lacking. Nanomaterials represent an obvious opportunity in this field due to their unique physicochemical properties. Gold nanostructures are being actively studied as a promising and versatile platform for biomedical application. Herein, we report novel surface-engineered gold nanorods (NRs) used as promising DNA vaccine adjuvant for HIV treatment. We have exploited the effects of surface chemistry on the adjuvant activity of the gold nanorod by placing three kinds of molecules, that is, cetyltrimethylammonium bromide (CTAB), poly(diallydimethylammonium chloride) (PDDAC), and polyethyleneimine (PEI) on the surface of the nanorod. These PDDAC- or PEI-modified Au NRs can significantly promote cellular and humoral immunity as well as T cell proliferation through activating antigen-presenting cells if compared to naked HIV-1 Env plasmid DNA treatment in vivo. These findings have shed light on the rational design of low-toxic nanomaterials as a versatile platform for vaccine nanoadjuvants/delivery systems.     

VA族单元素二维纳米材料在生物医用领域的研究进展

纳米材料在不同技术领域均有广泛应用,且在解决基础科学新发现上拥有巨大潜力。其中单元素构成的纳米材料因合成容易、制备简单而倍受关注,尤其VA族二维单元素纳米材料(包括黑磷、砷烯等)的物理、化学、电子和光学特性优异,在生物成像、药物递送和诊断治疗等生物医学领域应用前景广阔。本文总结了VA族二维单元素纳米材料的一般特性、合成和修饰方法,重点介绍了其面向各种生物医学应用的纳米平台的研究进展,最后,讨论了其在生物医学领域所面临的挑战并展望了未来的发展方向。     

Selenium nanomaterials: An overview of recent developments in synthesis,properties and potential applications

Advances in science and nanotechnology have facilitated the development of new methods for the preparation of pure selenium as selenium nanomaterials. They offer remarkable potential for technological applications in the fields of medicine, diagnostics, therapeutics, toxicology, electronics, catalysis and so on. Moreover, selenium nanomaterials also find applications in photographic exposure metres, rectifiers, signal emitting devices and transmitting devices, because of their unique structural, optical and electronic properties. This study describes a detailed advanced report on the synthesis, assembly, characterization and various applications of selenium nanomaterials. In addition, relevant synthesis methods, properties, challenges and opportunities associated with selenium nanomaterials are also presented.     

Ultrathin 2D Rare-Earth Nanomaterials: Compositions,Syntheses, and Applications

Ultrathin 2D nanomaterials possess promising properties due to electron confinement within single or a few atom layers. As an emerging class of functional materials, ultrathin 2D rare-earth nanomaterials may incorporate the unique optical, magnetic, and catalytic behaviors of rare-earth elements into layers, exhibiting great potential in various applications such as optoelectronics, magnetic devices, transistors, high-efficiency catalysts, etc. Despite its importance, reviews on ultrathin 2D rare-earth nanomaterials or related topics are rare and only focus on a certain family of ultrathin 2D rare-earth nanomaterials. This work is the first comprehensive review in this impressive field, which covers all families of ultrathin 2D rare-earth nanomaterials, illustrating their compositions, syntheses, and applications. After summarizing the current achievements, the challenges and opportunities of future research on ultrathin 2D rare-earth nanomaterials are evaluated.