Technical Institute of Physics and Chemistry

In the past decade, mesoporous silica nanoparticles (MSNs) have attracted more and more attention for their potential biomedical applications. With their tailored mesoporous structure and high surface area, MSNs as drug delivery systems (DDSs) show significant advantages over traditional drug nanocarriers. In this review, we overview the recent progress in the synthesis of MSNs for drug delivery applications. First, we provide an overview of synthesis strategies for fabricating ordered MSNs and hollow/rattle-type MSNs. Then, the in vitro and in vivo biocompatibility and biotranslocation of MSNs are discussed in relation to their chemophysical properties including particle size, surface properties, shape, and structure. The review also highlights the significant achievements in drug delivery using mesoporous silica nanoparticles and their multifunctional counterparts as drug carriers. In particular, the biological barriers for nano-based targeted cancer therapy and MSN-based targeting strategies are discussed. We conclude with our personal perspectives on the directions in which future work in this field might be focused.

A facile synthetic strategy for nitrogen-deficient graphitic carbon nitride (g-C3Nx) is established, involving a simple alkali-assisted thermal polymerization of urea, melamine, or thiourea. In situ introduced nitrogen vacancies significantly redshift the absorption edge of g-C3Nx, with the defect concentration depending on the alkali to nitrogen precursor ratio. The g-C3Nx products show superior visible-light photocatalytic performance compared to pristine g-C3N4. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

During the past decade, fluorescent chemosensors have become an important research field of supramolecular chemistry and have attracted great attention because of their simplicity, high selectivity and sensitivity in fluorescent assays. In the design of new fluorescent chemosensors, exploration of new sensing mechanisms between recognition and signal reporting units is of continuing interest. Based on different photophysical processes, conventional sensing mechanisms including photo-induced electron transfer (PET), intramolecular charge transfer (ICT), metal-ligand charge transfer (MLCT), twisted intramolecular charge transfer (TICT), electronic energy transfer (EET), fluorescence resonance energy transfer (FRET), and excimer/exciplex formation have been investigated and reviewed extensively in the literature. This tutorial review will mainly focus on new fluorescent sensing mechanisms that have emerged in the past five years, such as aggregation-induced emission (AIE) and C=N isomerization, which can be ascribed to fluorescence changes via conformational restriction. In addition, excited-state intramolecular proton transfer (ESIPT) has not been well reviewed yet, although a number of chemosensors based on the ESIPT mechanism have been reported. Thus, ESIPT-based chemosensors have been also summarized in this review.

Clinical applications of current photodynamic therapy (PDT) agents are often limited by their low singlet oxygen (1O2) quantum yields, as well as by photobleaching and poor biocompatibility. Here we present a new PDT agent based on graphene quantum dots (GQDs) that can produce 1O2 via a multistate sensitization process, resulting in a quantum yield of ~1.3, the highest reported for PDT agents. The GQDs also exhibit a broad absorption band spanning the UV region and the entire visible region and a strong deep-red emission. Through in vitro and in vivo studies, we demonstrate that GQDs can be used as PDT agents, simultaneously allowing imaging and providing a highly efficient cancer therapy. The present work may lead to a new generation of carbon-based nanomaterial PDT agents with overall performance superior to conventional agents in terms of 1O2 quantum yield, water dispersibility, photo- and pH-stability, and biocompatibility. Photosensitisers are used in cancer therapy to promote the formation of reactive oxygen species on irradiation with light. Here, the authors present a graphene quantum dot photosensitiser with a singlet oxygen quantum yield of approximately 1.3, and investigate its in vitro and in vivoapplications

Superwettability is a special case of the wetting phenomenon among liquids, gases, and solids. The superhydrophobic/superhydrophilic effect discovered initially has undergone a century of development based on materials science and biomimetics. With the rapid development of research on anti-wetting materials, superoleophobic/superoleophilic surfaces have been fabricated to repel organic liquids besides water. Further studies of underwater superoleophobic/superoleophilic/superaerophobic/superaerophilic materials provide an alternative way to fabricate anti-wetting surfaces rather than lowering the surface energy. Owing to a series of efforts on the studying of extreme wettabilities, a mature superwettability system gradually evolved and has since become a vibrant area of active research, covering topics of superhydrophobicity/superhydrophilicity, superoleophobicity/superoleophilicity in gas or under liquid, superaerophobicity/superaerophilicity under liquid, and combinations of these states. The kinetic study of the superwettability system includes statics and dynamics, while the studied material structures range from traditional two-dimensional materials to three-dimensional, one-dimensional, and zero-dimensional materials. Furthermore, the wetting liquids range from water to oil, aqueous solutions, and ionic liquids, as well as liquid crystals and other types of liquids. The wetting conditions extend over a wide range of temperatures, pressures, and other external fields. With the development of this series of research, many new theories and functional interfacial materials have been fabricated, including self-cleaning textiles, oil/water separation systems, and water collection systems, and some of these have already been applied in industry. Moreover, the study of superwettability has also introduced many new phenomena and principles to the field of interfacial chemistry that display its vast potential in both materials and chemistry. The present Perspective aims to summarize the most recent research on these materials and their interfacial chemistry. An overview of novel materials in superwettability systems and interfacial materials is presented. Specifically, the evolution of superwettable materials will be introduced, and the fundamental rules for building these superwetting materials will be discussed, followed by a summary of recent progress in the application of superwettable materials to alter the behaviors of chemical reactants and products. Specific emphasis is placed on recent strategies that exploit superwettable materials to influence the performance of traditional chemical reactions and their unique contributions to chemistry, including the effective collection of reaction products, unique growth models of precipitates, and a simple strategy for the alignment/assembly of nanoscale building blocks. Finally, a short perspective is provided on the potential for future developments in the field.

Phototherapy, including photodynamic therapy and photothermal therapy, has the potential to treat several types of cancer. However, to be an effective anticancer treatment, it has to overcome limitations, such as low penetration depth, low target specificity, and resistance conferred by the local tumor microenvironment. As a non-invasive technique, low-intensity ultrasound has been widely used in clinical diagnosis as it exhibits deeper penetration into the body compared to light. Recently, sonodynamic therapy (SDT), a combination of low-intensity ultrasound with a chemotherapeutic agent (sonosensitizer), has been explored as a promising alternative for cancer therapy. As all known cancer treatments such as chemotherapy, photodynamic therapy, photothermal therapy, immunotherapy, and drug delivery have been advanced independently enough to complement others substantially, the combination of these therapeutic modalities with SDT is opportune. This review article highlights the recent advances in SDT in terms of sonosensitizers and their formulations and anticancer therapeutic efficacy. Also discussed is the potential of SDT in combination with other modalities to address unmet needs in precision medicine.

2D graphitic carbon nitride (GCN) nanosheets have attracted tremendous attention in photocatalysis due to their many intriguing properties. However, the photocatalytic performance of GCN nanosheets is still restricted by the limited active sites and the serious aggregation during the photocatalytic process. Herein, a simple approach to produce holey GCN (HGCN) nanosheets with abundant in‐plane holes by thermally treating bulk GCN (BGCN) under an NH 3 atmosphere is reported. These formed in‐plane holes not only endow GCN nanosheets with more exposed active edges and cross‐plane diffusion channels that greatly speed up mass and photogenerated charge transfer, but also provide numerous boundaries and thus decrease the aggregation. Compared to BGCN, the resultant HGCN has a much higher specific surface area of 196 m 2 g −1 , together with an enlarged bandgap of 2.95 eV. In addition, the HGCN is demonstrated to be self‐modified with carbon vacancies that make HGCN show much broader light absorption extending to the near‐infrared region, a higher donor density, and remarkably longer lifetime of charge carriers. As such, HGCN has a much higher photocatalytic hydrogen production rate of nearly 20 times the rate of BGCN.

Abstract As an emerging clinical modality for cancer treatment, photodynamic therapy (PDT) takes advantage of the cytotoxic activity of reactive oxygen species (ROS) that are generated by light irradiating photosensitizers (PSs) in the presence of oxygen (O 2 ). However, further advancements including tumor selectivity and ROS generation efficiency are still required. Substantial efforts are devoted to design and synthesize smart PSs with optimized properties for achieving a desirable therapeutic efficacy. This review summarizes the recent progress in developing intelligent PSs for efficient PDT, ranging from single molecules to delicate nanomaterials. The strategies to improve ROS generation through optimizing photoinduced electron transfer and energy transfer processes of PSs are highlighted. Moreover, the approaches that combine PDT with other therapeutics (e.g., chemotherapy, photothermal therapy, and radiotherapy) and the targeted delivery in cancer cells or tumor tissue are introduced. The main challenges for the clinical application of PSs are also discussed.

Abstract Efficient photo‐ and piezoelectric‐induced molecular oxygen activation are both achieved by macroscopic polarization enhancement on a noncentrosymmetric piezoelectric semiconductor BiOIO 3 . The replacement of V 5+ ions for I 5+ in IO 3 polyhedra gives rise to strengthened macroscopic polarization of BiOIO 3 , which facilitates the charge separation in the photocatalytic and piezoelectric catalytic process, and renders largely promoted photo‐ and piezoelectric induced reactive oxygen species (ROS) evolution, such as superoxide radicals ( . O 2 − ) and hydroxyl radicals ( . OH). This work advances piezoelectricity as a new route to efficient ROS generation, and also discloses macroscopic polarization engineering on improvement of multi‐responsive catalysis.

Chemical oxygen demand (CODCr) and proton NMR, UV−vis, and spin trapping EPR spectroscopic evidence is presented to demonstrate the inverse photosensitized oxidative transformation of tetraethylated rhodamine (RhB) under visible illumination of aqueous titania dispersions. Both de-ethylation and oxidative degradation take place with the former proceeding in a stepwise manner to yield mono-, di-, tri-, and tetra-de-ethylated rhodamine species. Intermediates present after each de-ethylation step remain in a fast dynamic equilibrium between the titania particle surface and the bulk solution. The concentration of • OH radicals, formed from the inverse photosensitization process through the superoxide radical anion, increases upon addition of the anionic dodecylbenzene sulfonate surfactant (DBS) because a larger number of RhB excited states are able to inject an electron into the conduction band of the TiO 2 particles. Also, intermediates that can no longer absorb the visible light, (i.e., once the dye solution is competely bleached) are unable to drive the photosensitized degradation further. A mechanism for the competitive photoreactions between degradation and de-ethylation is described, in which de-ethylation {ζ ∼ 0.0035} is mostly a surface occurring process, whereas degradation {ζ ∼ 0.0015}of the RhB chromophore is predominantly a solution bulk process.

Abstract Dinitrogen reduction to ammonia using transition metal catalysts is central to both the chemical industry and the Earth's nitrogen cycle. In the Haber–Bosch process, a metallic iron catalyst and high temperatures (400 °C) and pressures (200 atm) are necessary to activate and cleave NN bonds, motivating the search for alternative catalysts that can transform N 2 to NH 3 under far milder reaction conditions. Here, the successful hydrothermal synthesis of ultrathin TiO 2 nanosheets with an abundance of oxygen vacancies and intrinsic compressive strain, achieved through a facile copper‐doping strategy, is reported. These defect‐rich ultrathin anatase nanosheets exhibit remarkable and stable performance for photocatalytic reduction of N 2 to NH 3 in water, exhibiting photoactivity up to 700 nm. The oxygen vacancies and strain effect allow strong chemisorption and activation of molecular N 2 and water, resulting in unusually high rates of NH 3 evolution under visible‐light irradiation. Therefore, this study offers a promising and sustainable route for the fixation of atmospheric N 2 using solar energy.

Abstract Piezoelectric‐based catalysis that relies on the charge energy or separation efficiency of charge carriers has attracted significant attention. The piezo‐potential induced by strain or stress can induce a giant electric field, which has been demonstrated to be an effective means for charge energy shifting or transferring electrons and holes. In recent years, intense efforts have been made in this subject, and the research has mainly focussed on two aspects: i) Alteration of surface charge energy by piezo‐potential in piezocatalysis; ii) the separation of photo‐generated charge carriers and the catalytic activity enhancement of an integrated piezoelectric semiconductor or coupled system composed of piezoelectrics and semiconductors. Systematically summarizing the advances of the above two aspects is helpful in the context of deepening understanding of the relevant issues and developing new ideas for piezoelectric‐based catalysis. In this review, a comprehensive summary on piezocatalysis and piezo‐photocatalysis is provided. The charge transfer behaviors and catalytic mechanisms over a large variety of piezocatalysts and piezo‐photocatalysts are systematically analyzed. In addition, the types of mechanical energy, strategies for enhancing piezocatalysis, and the advanced applications of piezocatalysis and piezo‐photocatalysis are discussed. Finally, the promising development directions of piezocatalysis and piezo‐photocatalysis, such as materials, assembly forms, and applications in the future are proposed.

In our previous study we reported that the interaction of nanoparticles with cells can be influenced by particle shape, but until now the effect of particle shape on in vivo behavior remained poorly understood. In the present study, we control the fabrication of fluorescent mesoporous silica nanoparticles (MSNs) by varying the concentration of reaction reagents especially to design a series of shapes. Two different shaped fluorescent MSNs (aspect ratios, 1.5, 5) were specially designed, and the effects of particle shape on biodistribution, clearance and biocompatibility in vivo were investigated. Organ distributions show that intravenously administrated MSNs are mainly present in the liver, spleen and lung (>80%) and there is obvious particle shape effects on in vivo behaviors. Short-rod MSNs are easily trapped in the liver, while long-rod MSNs distribute in the spleen. MSNs with both aspect ratios have a higher content in the lung after PEG modification. We also found MSNs are mainly excreted by urine and feces, and the clearance rate of MSNs is primarily dependent on the particle shape, where short-rod MSNs have a more rapid clearance rate than long-rod MSNs in both excretion routes. Hematology, serum biochemistry, and histopathology results indicate that MSNs would not cause significant toxicity in vivo, but there is potential induction of biliary excretion and glomerular filtration dysfunction. These findings may provide useful information for the design of nanoscale delivery systems and the environmental fate of nanoparticles.

We report a ratiometric fluorescent sensor based on monochlorinated BODIPY for highly selective detection of glutathione (GSH) over cysteine (Cys)/homocysteine (Hcy). The chlorine of the monochlorinated BODIPY can be rapidly replaced by thiolates of biothiols through thiol-halogen nucleophilic substitution. The amino groups of Cys/Hcy but not GSH further replace the thiolate to form amino-substituted BODIPY. The significantly different photophysical properties of sulfur- and amino-substituted BODIPY enable the discrimination of GSH over Cys and Hcy. The sensor was applied for detection of GSH in living cells.

Novel red-emissive carbon-dots (C-dots) with broad absorption in the region from 400 to 750 nm are prepared from polythiophene phenylpropionic acid. Upon near infrared laser irradiation, the red-emissive C-dots show strong photoacoustic response and high photothermal conversion efficiency (η ≈ 38.5%). These unique properties enable the C-dots to act as multifunctional fluorescent, photoacoustic, and thermal theranostics for simultaneous diagnosis and therapy of cancer. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

A cylindrical piece of Au/graphene hydrogel, 1.08 cm in diameter and 1.28 cm in height, has been synthesized through the self-assembly of Au/graphene sheets under hydrothermal conditions for the first time. The hydrogel, containing 2.26 wt% Au, 6.94 wt% graphene, and 90.8 wt% water, exhibited excellent catalytic performance towards the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP), which is about 90 times larger than previously reported values for spongy Au nanoparticles and 14 times more than the highest value among the polymer supported Au nanoparticle catalysts. The high catalytic activity arises from the synergistic effect of graphene: (1) the high adsorption ability of graphene towards 4-NP, providing a high concentration of 4-NP near to the Au nanoparticles on graphene; and (2) electron transfer from graphene to Au nanoparticles, facilitating the uptake of electrons by 4-NP molecules.

Simple thiol derivatives, such as cysteine (Cys), homocysteine (Hcy), and glutathione (GSH), play key roles in biological processes, and the fluorescent probes to detect such thiols in vivo selectively with high sensitivity and fast response times are critical for understanding their numerous functions. However, the similar structures and reactivities of these thiols pose considerable challenges to the development of such probes. This review focuses on various strategies for the design of fluorescent probes for the selective detection of biothiols. We classify the fluorescent probes for discrimination among biothiols according to reaction types between the probes and thiols such as cyclization with aldehydes, conjugate addition-cyclization with acrylates, native chemical ligation, and aromatic substitution-rearrangement.

Nitrogen-doped porous carbon nanosheets (N-CNS) are synthesized by hydrothermal carbon coating of g-C3N4 nanosheets followed by high-temperature treatment in N2. g-C3N4 serves as a template, nitrogen source, and porogen in the synthesis. This approach yields N-CNS with a high nitrogen content and comparable oxygen reduction reaction catalytic activities to commercial Pt/C catalysts in alkaline media. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Sulfur is a promising cathode material for lithium-sulfur batteries because of its high theoretical capacity (1,675 mA h g(-1)); however, its low electrical conductivity and the instability of sulfur-based electrodes limit its practical application. Here we report a facile in situ method for preparing three-dimensional porous graphitic carbon composites containing sulfur nanoparticles (3D S@PGC). With this strategy, the sulfur content of the composites can be tuned to a high level (up to 90 wt%). Because of the high sulfur content, the nanoscale distribution of the sulfur particles, and the covalent bonding between the sulfur and the PGC, the developed 3D S@PGC cathodes exhibit excellent performance, with a high sulfur utilization, high specific capacity (1,382, 1,242 and 1,115 mA h g(-1) at 0.5, 1 and 2 C, respectively), long cycling life (small capacity decay of 0.039% per cycle over 1,000 cycles at 2 C) and excellent rate capability at a high charge/discharge current.

Abstract Solar-driven water evaporation represents an environmentally benign method of water purification/desalination. However, the efficiency is limited by increased salt concentration and accumulation. Here, we propose an energy reutilizing strategy based on a bio-mimetic 3D structure. The spontaneously formed water film, with thickness inhomogeneity and temperature gradient, fully utilizes the input energy through Marangoni effect and results in localized salt crystallization. Solar-driven water evaporation rate of 2.63 kg m −2 h −1 , with energy efficiency of >96% under one sun illumination and under high salinity (25 wt% NaCl), and water collecting rate of 1.72 kg m −2 h −1 are achieved in purifying natural seawater in a closed system. The crystalized salt freely stands on the 3D evaporator and can be easily removed. Additionally, energy efficiency and water evaporation are not influenced by salt accumulation thanks to an expanded water film inside the salt, indicating the potential for sustainable and practical applications.