Recent advances in nanoscience and nanotechnology radically changed the way we diagnose, treat, and prevent various diseases in all aspects of human life. Silver nanoparticles (AgNPs) are one of the ...most vital and fascinating nanomaterials among several metallic nanoparticles that are involved in biomedical applications. AgNPs play an important role in nanoscience and nanotechnology, particularly in nanomedicine. Although several noble metals have been used for various purposes, AgNPs have been focused on potential applications in cancer diagnosis and therapy. In this review, we discuss the synthesis of AgNPs using physical, chemical, and biological methods. We also discuss the properties of AgNPs and methods for their characterization. More importantly, we extensively discuss the multifunctional bio-applications of AgNPs; for example, as antibacterial, antifungal, antiviral, anti-inflammatory, anti-angiogenic, and anti-cancer agents, and the mechanism of the anti-cancer activity of AgNPs. In addition, we discuss therapeutic approaches and challenges for cancer therapy using AgNPs. Finally, we conclude by discussing the future perspective of AgNPs.
Carbon dots (Cdots) are an important probe for imaging and sensing applications because of their fluorescence property, good biocompatibility, and low toxicity. However, complex procedures and strong ...acid treatment are often required and Cdots suffer from low photoluminescence (PL) emission. Herein, a facile and general strategy using carbonization of precursors and then extraction with solvents is proposed for the preparation of nitrogen‐doped Cdots (N‐Cdots) with 3‐(3,4‐dihydroxyphenyl)‐L‐alanine (L‐DOPA), L‐histidine, and L‐arginine as precursor models. After they are heated, the precursors become carbonized. Nitrogen‐doped Cdots are subsequently extracted into N,N′‐dimethylformamide (DMF) from the carbogenic solid. A core–shell structure of Cdots with a carbon core and the oxygen‐containing shell was observed. Nitrogen has different forms in N‐Cdots and oxidized N‐Cdots. The doped nitrogen and low oxidation level in N‐Cdots improve their emission significantly. The N‐Cdots show an emission with a nitrogen‐content‐dependent intensity and Cdot‐size‐dependent emission‐peak wavelength. Imaging of HeLa cells, a human cervical cancer cell line, and HepG2 cells, a human hepatocellular liver carcinoma line, was observed with high resolution using N‐Cdots as a probe and validates their use in imaging applications and their multicolor property in the living cell system.
Going dotty: A facile and general strategy involving the carbonization of precursors and their subsequent extraction with solvents is proposed for the preparation of nitrogen‐doped carbon dots (N‐Cdots) with multicolor emission (see figure). The emission mechanism of the Cdots was studied. Multicolor photoluminescence was validated in living cell systems.
Silver nanoparticles (AgNPs) have attracted increased interest and are currently used in various industries including medicine, cosmetics, textiles, electronics, and pharmaceuticals, owing to their ...unique physical and chemical properties, particularly as antimicrobial and anticancer agents. Recently, several studies have reported both beneficial and toxic effects of AgNPs on various prokaryotic and eukaryotic systems. To develop nanoparticles for mediated therapy, several laboratories have used a variety of cell lines under in vitro conditions to evaluate the properties, mode of action, differential responses, and mechanisms of action of AgNPs. In vitro models are simple, cost-effective, rapid, and can be used to easily assess efficacy and performance. The cytotoxicity, genotoxicity, and biocompatibility of AgNPs depend on many factors such as size, shape, surface charge, surface coating, solubility, concentration, surface functionalization, distribution of particles, mode of entry, mode of action, growth media, exposure time, and cell type. Cellular responses to AgNPs are different in each cell type and depend on the physical and chemical nature of AgNPs. This review evaluates significant contributions to the literature on biological applications of AgNPs. It begins with an introduction to AgNPs, with particular attention to their overall impact on cellular effects. The main objective of this review is to elucidate the reasons for different cell types exhibiting differential responses to nanoparticles even when they possess similar size, shape, and other parameters. Firstly, we discuss the cellular effects of AgNPs on a variety of cell lines; Secondly, we discuss the mechanisms of action of AgNPs in various cellular systems, and try to elucidate how AgNPs interact with different mammalian cell lines and produce significant effects; Finally, we discuss the cellular activation of various signaling molecules in response to AgNPs, and conclude with future perspectives on research into AgNPs.
The flexible Li‐air battery (FLAB) with ultrahigh energy density is a hopeful candidate for flexible energy storage devices. However, most current FLAB operate in a pure oxygen atmosphere, which is ...limited by safety and corrosion issues from the metallic lithium anode and has thus greatly impeded the application of FLAB. Now, inspired by the protection effect of the umbrella, a stable hydrophobic composite polymer electrolyte (SHCPE) film with high flexibility, hydrophobicity, and stability was fabricated to protect the lithium anode. The SHCPE mitigated lithium corrosion and improved the capacity, rate performance, and cycle life (from 24 cycles to 95 cycles) of a battery in the ambient air. Based on the protection of SHCPE and the catalysis of MnOOH, the prepared pouch‐type FLAB displayed high flexibility, stable performances, long cycling life (180 cycles), and excellent safety; the battery can bear soaking in water, high temperature, and nail penetration.
Hold up an umbrella! A stable hydrophobic composite polymer electrolyte inspired by umbrellas was designed and fabricated on a lithium anode for a flexible Li‐air battery that can safely operate in the ambient air. Based on the in situ fabricated multifunctional electrolyte, the pouch‐type flexible Li‐air battery showed stable electrochemical performance and safety even under extreme conditions.
Sodium‐ion batteries (SIBs) are considered as promising alternatives to lithium‐ion batteries (LIBs) for large‐scale electrical‐energy‐storage applications due to the wide availability and the low ...cost of Na resources. Along with the avenues of research on flexible LIBs, flexible SIBs are now being actively developed as one of the most promising power sources for the emerging field of flexible and wearable electronic devices. Here, the recent progress on flexible electrodes based on metal substrates, carbonaceous substrates (i.e., graphene, carbon cloth, and carbon nanofibers), and other materials, as well as their applications in flexible SIBs, are summarized. Also, some future research directions for constructing flexible SIBs are proposed, with the aim of providing inspiration to the further development of advanced flexible SIBs.
Flexible sodium‐ion batteries (SIBs) are being actively developed as one of the most promising power sources for the emerging field of flexible and wearable electronic devices. The recent progress on flexible electrodes based on metal substrates, carbonaceous substrates, and other materials, is summarized, along with their applications in flexible SIBs.
By introducing anisotropic micropatterns on a superhydrophobic surface, we demonstrate that water microdroplets can coalesce and leap over the surface spontaneously along a prescribed direction. This ...controlled behavior is attributed to anisotropic liquid–solid adhesion. An analysis relating the preferential leaping probability to the geometrical parameters of the system is presented with consistent experimental results. Surfaces with this rare quality demonstrate many unique characteristics, such as self‐powered, and relatively long‐distance transport of microdroplets by “relay” coalescence‐induced leaping.
Jumping Jack Flash: Water microdroplets can coalesce and leap over the surface spontaneously along a prescribed direction upon introducing anisotropic micropatterns onto superhydrophobic surfaces. These surfaces offer efficient self‐powered and relatively long‐distance transport of microdroplets by “relay” coalescence‐induced leaping and effective self‐sustained microcarriers.
The flexible Li‐O2 battery is suitable to satisfy the requirements of a self‐powered energy system, thanks to environmental friendliness, low cost, and high theoretical energy density. Herein, a ...flexible porous bifunctional electrode with both electrocatalytic and photocatalytic activity was synthesized and introduced as a cathode to assemble a high‐performance Li‐O2 battery that achieved an overpotential of 0.19 V by charging with the aid of solar energy. As a proof‐of‐concept application, a flexible Li‐O2 battery was constructed and integrated with a solar cell via a scalable encapsulate method to fabricate a flexible self‐powered energy system with excellent flexibility and mechanical stability. Moreover, by exploring the evolution of the electrode morphology and discharge products (Li2O2), the charging process of the Li‐O2 battery powered by solar energy and solar cell was demonstrated.
A flexible self‐powered energy system was fabricated by combining a flexible Li‐O2 battery with a flexible solar cell. By exploring the evolution of the electrode morphology and discharge products (Li2O2), the charging process of the Li‐O2 battery powered by solar energy and solar cell is demonstrated.
Sialon ceramics were prepared by the nitridation of Si, Al and Al
2
O
3
powders with the transition metals (Fe, Co, Ni) catalysts. The phase composition, microstructure and mechanical properties of ...specimens were studied. Compared with the catalyst-free specimen, the addition of Fe, Co and Ni greatly promoted the nitridation process of Sialon ceramics and improved the weight gain rate and mechanical properties of specimens. With the increased content of catalysts, the apparent porosity of the products decreased first and then increased, contrary to flexural strength and compressive strength. The specimen with 2.5 wt% Fe had the highest flexural strength 145.8 MPa, and it exhibited the highest compressive strength of 594.6 MPa when Co content was 2.5 wt%, whereas they were 71.9 and 78.7 MPa, respectively, when without catalyst.
Graphic abstract
The study of the composition, morphology, and surface structure of carbon dots (Cdots) is critical to understanding their effect on the photo‐ and electrochemiluminescence (PL and ECL) of Cdots in ...selected applications. Herein, two kinds of Cdots were prepared with 3‐(3,4‐dihydroxyphenyl)‐L‐alanine (L‐DOPA) as precursor. The Cdots prepared by using a carbonization‐extraction strategy have a low oxidation level and are denoted as reduced Cdots (r‐Cdots). The Cdots obtained with a carbonization‐oxidation process are highly oxidized and are denoted as oxidized Cdots (o‐Cdots). The o‐Cdots have a carbon core and oxygen‐containing loose shell, but the r‐Cdots consist mainly of the carbon core. Whereas r‐Cdots have a strong blue PL but no apparent ECL response, o‐Cdots exhibit a relatively weak PL and strong ECL emission. These properties allow for selected applications of the Cdots. The r‐Cdots were used in cell imaging with their high PL emission. The o‐Cdots, with their high ECL efficiencies, were selected to sense Cu2+ with Cu2+‐inducing ECL quenching in the o‐Cdots/K2S2O8 system. This work provides the possibility to control the composition of Cdots for selected applications and shows a good way to characterize surface traps of Cdots because ECL is characterized by the surface‐state and PL is mainly related to the core‐state in Cdots.
Joining the Cdots: Two kinds of carbon dots (Cdots), with different oxidation levels, were successfully prepared through a carbogenic and then extraction or oxidation process. Their photoluminescence (PL) and electrochemiluminescence (ECL) properties were carefully studied for selected applications in cell imaging and metal‐ion detection (see figure; CB=conduction band, VB=valence band).
Zinc oxide nanoparticles (ZnO NPs) are frequently used in industrial products such as paint, surface coating, and cosmetics, and recently, they have been explored in biologic and biomedical ...applications. Therefore, this study was undertaken to investigate the effect of ZnO NPs on cytotoxicity, apoptosis, and autophagy in human ovarian cancer cells (SKOV3).
ZnO NPs with a crystalline size of 20 nm were characterized with various analytical techniques, including ultraviolet-visible spectroscopy, X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, and atomic force microscopy. The cytotoxicity, apoptosis, and autophagy were examined using a series of cellular assays.
Exposure of cells to ZnO NPs resulted in a dose-dependent loss of cell viability, and the characteristic apoptotic features such as rounding and loss of adherence, enhanced reactive oxygen species generation, and loss of mitochondrial membrane potential were observed in the ZnO NP-treated cells. Furthermore, the cells treated with ZnO NPs showed significant double-strand DNA breaks, which are gained evidences from significant number of γ-H
AX and Rad51 expressed cells. ZnO NP-treated cells showed upregulation of p53 and LC3, indicating that ZnO NPs are able to upregulate apoptosis and autophagy. Finally, the Western blot analysis revealed upregulation of Bax, caspase-9, Rad51, γ-H
AX, p53, and LC3 and downregulation of Bcl-2.
The study findings demonstrated that the ZnO NPs are able to induce significant cytotoxicity, apoptosis, and autophagy in human ovarian cells through reactive oxygen species generation and oxidative stress. Therefore, this study suggests that ZnO NPs are suitable and inherent anticancer agents due to their several favorable characteristic features including favorable band gap, electrostatic charge, surface chemistry, and potentiation of redox cycling cascades.
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