Chondroitin sulfate/silk fibroin hydrogel incorporating graphene oxide quantum dots with photothermal-effect promotes type H vessel-related wound healing

Chronic wounds with bacterial infection present formidable clinical challenges. In this study, a versatile hydrogel dressing with antibacterial and angiogenic activity composite of silk fibroin (SF), chondroitin sulfate (CS), and graphene oxide quantum dots (GOQDs) is fabricated. GOQDs@SF/CS (GSC) hydrogel is rapidly formed through the enzyme catalytic action of horseradish peroxidase. With the incorporation of GOQDs both gelation speed and mechanical properties have been enhanced, and the photothermal characteristics of GOQDs in GSC hydrogel enabled bacterial killing through photothermal treatment (PTT) at ∼51 °C. In vitro studies show that the GSC hydrogels demonstrate excellent antibacterial performance and induce type H vessel differentiation of endothelial cells via the activated ERK1/2 signaling pathway and upregulated SLIT3 expression. In vivo results show that the hydrogel significantly promotes type H vessels formation, which is related to the collagen deposition, epithelialization and, ultimately, accelerates the regeneration of infected skin defects. Collectively, this multifunctional GSC hydrogel, with dual action of antibacterial efficacy and angiogenesis promotion, emerges as an innovative skin dressing with the potential for advancing in infected wound healing.

Preparation of MnO2-Carbon Materials and Their Applications in Photocatalytic Water Treatment

Water pollution is one of the most important problems in the field of environmental protection in the whole world, and organic pollution is a critical one for wastewater pollution problems. How to solve the problem effectively has triggered a common concern in the area of environmental protection nowadays. Around this problem, scientists have carried out a lot of research; due to the advantages of high efficiency, a lack of secondary pollution, and low cost, photocatalytic technology has attracted more and more attention. In the past, MnO₂ was seldom used in the field of water pollution treatment due to its easy agglomeration and low catalytic activity at low temperatures. With the development of carbon materials, it was found that the composite of carbon materials and MnO₂ could overcome the above defects, and the composite had good photocatalytic performance, and the research on the photocatalytic performance of MnO₂-carbon materials has gradually become a research hotspot in recent years. This review covers recent progress on MnO₂-carbon materials for photocatalytic water treatment. We focus on the preparation methods of MnO₂ and different kinds of carbon material composites and the application of composite materials in the removal of phenolic compounds, antibiotics, organic dyes, and heavy metal ions in water. Finally, we present our perspective on the challenges and future research directions of MnO₂-carbon materials in the field of environmental applications.

Quantum Dots for Cancer-Related miRNA Monitoring

Quantum dots (QDs) possess exceptional optoelectronic properties that enable their use in the most diverse applications, namely, in the medical field. The prevalence of cancer has increased and has been considered the major cause of death worldwide. Thus, there has been a great demand for new methodologies for diagnosing and monitoring cancer in cells to provide an earlier prognosis of the disease and contribute to the effectiveness of treatment. Several molecules in the human body can be considered relevant as cancer markers. Studies published over recent years have revealed that micro ribonucleic acids (miRNAs) play a crucial role in this pathology, since they are responsible for some physiological processes of the cell cycle and, most important, they are overexpressed in cancer cells. Thus, the analytical sensing of miRNA has gained importance to provide monitoring during cancer treatment, allowing the evaluation of the disease's evolution. Recent methodologies based on nanochemistry use fluorescent quantum dots for sensing of the miRNA. Combining the unique characteristics of QDs, namely, their fluorescence capacity, and the fact that miRNA presents an aberrant expression in cancer cells, the researchers created diverse strategies for miRNA monitoring. This review aims to present an overview of the recent use of QDs as biosensors in miRNA detection, also highlighting some tutorial descriptions of the synthesis methods of QDs, possible surface modification, and functionalization approaches.

Green synthetic nitrogen-doped graphene quantum dot fluorescent probe for the highly sensitive and selective detection of tetracycline in food samples

Tetracycline (TC) is a broad-spectrum antibiotic. When humans consume too much food containing tetracycline residues, it can be a serious health hazard. Therefore, it is essential to develop a strategy to detect TC. In this study, we prepared light blue-green luminescent nitrogen-doped graphene quantum dots (N-GQDs) by a hydrothermal method using the natural products potato straight-chain starch and urea as precursors; the fluorescence quantum yield of the prepared N-GQDs was 5.2%. We investigated the detection of tetracycline (TC) by this N-GQD fluorescent sensor based on the internal filtration effect (IFE) of TC on N-GQDs. The reaction is green, simple and no other contaminating products are present. A good linear relationship was established between the relative fluorescence intensity ratio of the system and the logarithm of the TC concentration of 2.5 × 10⁻¹⁰ to 5 × 10⁻⁶ M (R² = 0.9930), with a detection limit of 9.735 × 10⁻¹³ M. The method has been used to analyze TC in three real food samples (whole milk, skim milk, honey) with low detection limits (3.750 × 10⁻¹¹ to 2.075 × 10⁻⁹ M), wide linear range, and satisfactory recoveries of 93.80–109.20% were obtained. In conclusion, the proposed method is a green, rapid, highly sensitive and selective method for the detection of tetracycline in real food samples, demonstrating the potential application of N-GQDs in food detection.

Tetracycline (TC) is a broad-spectrum antibiotic.

Quantum dots/graphene nanohybrids photodetectors: progress and perspective

Semiconductor quantum dots/graphene heterostructure nanohybrids combine the advantages of the enhanced light–matter interaction and spectral tunability of quantum dots (QDs) and high charge mobility in graphene as a charge transport pathway, providing a unique platform for exploration of photodetectors with high performance. In particular, the QDs/graphene nanohybrids allow resolution to the critical issue of charge transport in QDs-only photodetectors stemming from the low charge mobility associated with both QD surface defect states and inter-QD junctions. Furthermore, the achieved capability in industrial-scale fabrication of graphene and colloidal QDs has motivated efforts in research of QDs/graphene nanohybrids focal plane arrays that are expected to be not only high performance and low cost, but also light-weight, flexible and wearable. This paper aims to highlight recent progress made in the research and development of QDs/graphene nanohybrid photodetectors and discuss the challenges remained towards their commercial applications.

Fabrication of graphene: CdSe quantum dots/CdS nanorod heterojunction photodetector and role of graphene to enhance the photoresponsive characteristics

Integration of graphene with semiconducting quantum dots (QDs) provides an elegant way to access the intrinsic properties of graphene and optical properties of QDs concurrently to realize the high-performance optoelectronic devices. In the current article, we have demonstrated the high-performance photodetector based on graphene: CdSe QDs/CdS nanorod heterostructures. The resulting heterojunction photodetector with device configuration ITO/graphene: CdSe/CdS nanorods/Ag show excellent operating characteristics including a maximum photoresponsivity of 15.95 AW^-1and specific detectivity of 6.85 × 10¹²Jones under 530 nm light illumination. The device exhibits a photoresponse rise time of 545 ms and a decay time of 539 ms. Furthermore, the study of the effect of graphene nanosheets on the performance enhancement of heterojunction photodetector is carried out. The results indicate that, due to the enhanced energy transfer from photoexcited QDs to graphene layer, light absorption is increased and excitons are generated led to the enhancement of photocurrent density. In addition to that, the graphene: CdSe QDs/CdS nanorod interface can facilitate charge carrier transport effectively. This work provides a promising approach to develop high-performance visible-light photodetectors and utilizing advantageous features of graphene in optoelectronic devices.

Interface Engineering of Silicon/Carbon Thin-Film Anodes for High-Rate Lithium-Ion Batteries

Silicon is one of the most promising alternative active materials for next-generation lithium-ion battery (LIB) applications due to its advantage of high specific capacity. However, the enormous volume variations during lithiation/delithiation still remain to be an obstacle to commercialization. In this work, binder-free pure silicon and silicon/carbon (Si/C) multilayer thin-film electrodes, prepared by scalable one-step magnetron sputtering, are systematically investigated by an interlayer strategy. Herein, we present a rationally structural modification by an amorphous carbon film to enhance the electrical conductivity, mechanical integrity, and electrochemical performance of Si film-based LIBs. Therefore, to maintain the consistency of the direct-contact layer with the electrolyte and current collection, symmetrical Si/C/Si and Si/C/Si/C/Si/C/Si electrodes are deliberately designed to study the influence of embedded carbon. An anode with a carbon content of 10.38 wt % yields an initial discharge specific capacity of 1888.74 mAh g^-1 and a capacity retention of 96.82% (1243.56 mAh g^-1) after 150 cycles at a high current density of 4000 mA g^-1. It also shows that the best rate capability remains 96.0% of the initial capacity in the 70th cycle. At last, three mechanisms are proposed for an in-depth understanding of the interface effect. This work offers a new perspective scheme toward Si/C-based LIBs with a capability of high rate and high energy density.

Solution Processing and Self-Organization of PbS Quantum Dots Passivated with Formamidinium Lead Iodide (FAPbI3)

Solution-processed lead sulfide quantum dots (PbS QDs) are very attractive as NIR-active semiconductors for the fabrication of cost-efficient optoelectronic devices. To control the thin film carrier transport, as well as stability, surface passivation is of crucial importance. Here, we present the successful surface passivation of PbS QDs by the formamidinium lead iodide (FAPbI3) ligand. An effective procedure for the fabrication of FAPbI3-passivated PbS QDs through a binary-phase ligand exchange protocol in hexane and n-methylformamide is demonstrated. It is shown that this solution-processed ligand exchange drastically changes the photoluminescence intensity, exciton recombination dynamics, and carrier lifetime of the nanocrystals. The solution casting of the ligand-exchanged nanocrystals into thin films results in the periodic ordering of QDs in a square superlattice with close contacts. Planar graphene/QD photodetectors fabricated with PbS QDs passivated with FAPbI3 show substantially increased thermal stability as compared to similar devices using PbS QDs passivated with commonly used methylammonium lead iodide.

A universal growth strategy for DNA-programmed quantum dots on graphene oxide surfaces

The emerging materials of semiconductor quantum dots/graphene oxide (QDs/GO) hybrid composites have recently attracted intensive attention in materials science and technology due to their potential applications in electronic and photonic devices. Here, a simple and universal strategy to produce DNA-programmed semiconductor quantum dots/graphene oxide (QDs/GO) hybrid composites with controllable sizes, shapes, compositions, and surface properties is reported. This proof-of-concept work successfully demonstrates the use of sulfhydryl modified single-stranded DNA (S-ssDNA) as a 'universal glue' which can adsorb onto GO easily and provide the growth sites to synthesize CdS QDs, CdSe QDs, CdTe QDs and CdTeSe QDs with distinctive sizes, shapes and properties. Also, adapting this method, other graphene oxide-based hybrid materials which are easily synthesized in aqueous solution, including oxides, core-shell structure QDs and metal nanocrystals, would be possible. This method provided a universal strategy for the synthesis and functional realization of graphene -based nanomaterials.

A high-sensitive sensor with HEPES-enhanced electrochemiluminescence of benzo[3]uril for Fe3+ and its application in human serum

An electrochemiluminescence (ECL) sensor based on a benzo[3]uril-modified glassy carbon electrode with sensitized luminescence, with the coexistence of 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) as the coreactant, was successfully constructed. The sensitization mechanism was proposed by analyzing the results of the control experiments for establishing the relationship of the luminescence effect with the concentration of HEPES. Under the optimized conditions, the fabricated sensor system was applied for the detection of Fe³⁺ in an aqueous solution with good sensitivity and selectivity. A low detection limit of 0.41 nM was achieved, indicating superior sensor performance over the previous analytical methods. The ECL sensor system was employed for the detection of Fe³⁺ in human serum samples to produce excellent recoveries ranging from 96.17% to 101.81%.

Screening and characterisation of CdTe/CdS quantum dot-binding peptides for material surface functionalisation

Quantum dots (QDs) are promising nanomaterials due to their unique photophysical properties. For them to be useful in biological applications, the particle surface generally needs to be conjugated to biological molecules, such as antibodies. In this study, we screened CdTe/CdS QD-binding peptides from a phage display library as linkers for simple and bio-friendly QD modification. Among five QD-binding peptide candidates, a series of truncated peptides designed from two high-affinity peptides were subjected to an array-based binding assay with QDs to assess their functional core sequences and characteristics. Linking these isolated, shortened peptides (PWSLNR and SGVYK) with an antibody-binding peptide (NKFRGKYK) created dual-functional peptides that are capable of QD surface functionalisation by antibodies. Consequently, the dual-functional peptides could mediate anti-CD9 antibody functionalisation onto CdTe/CdS QD surface; CD9 protein imaging of cancer cells was also demonstrated. Our proposed peptides offer an effective vehicle for QD surface functionalisation in biological applications.

Porous g-C3N4 and MXene Dual-Confined FeOOH Quantum Dots for Superior Energy Storage in an Ionic Liquid

Owing to their unique nanosize effect and surface effect, pseudocapacitive quantum dots (QDs) hold considerable potential for high-efficiency supercapacitors (SCs). However, their pseudocapacitive behavior is exploited in aqueous electrolytes with narrow potential windows, thereby leading to a low energy density of the SCs. Here, a film electrode based on dual-confined FeOOH QDs (FQDs) with superior pseudocapacitive behavior in a high-voltage ionic liquid (IL) electrolyte is put forward. In such a film electrode, FQDs are steadily dual-confined in a 2D heterogeneous nanospace supported by graphite carbon nitride (g-C3N4) and Ti-MXene (Ti3C2). Probing of potential-driven ion accumulation elucidates that strong adsorption occurs between the IL cation and the electrode surface with abundant active sites, providing sufficient redox reaction of FQDs in the film electrode. Furthermore, porous g-C3N4 and conductive Ti3C2 act as ion-accessible channels and charge-transfer pathways, respectively, endowing the FQDs-based film electrode with favorable electrochemical kinetics in the IL electrolyte. A high-voltage flexible SC (FSC) based on an ionogel electrolyte is fabricated, exhibiting a high energy density (77.12 mWh cm-3), a high power density, a remarkable rate capability, and long-term durability. Such an FSC can also be charged by harvesting sustainable energy and can effectively power various wearable and portable electronics.

Aluminum nanocomposites reinforced with monolayer polyaniline (C3N): assessing the mechanical and ballistic properties

This study unveils C₃N, a new material that serves as an excellent reinforcement to enhance the mechanical properties of aluminum using a molecular dynamics simulation method. Results show that the C₃N nanosheets greatly improve the mechanical properties of aluminum-based nanocomposites. With only 1.3 wt% C₃N, the Young's modulus, fracture strength, and fracture strain increased by 27, 70, and 51 percent, respectively. A comparison between the reinforcement of graphene and C₃N in an aluminum (Al) matrix shows that in terms of the mechanical properties, the graphene–aluminum composite is weaker than the C₃N–aluminum composite in the tensile tests, but slightly stronger in the energy adsorption tests. Our findings show that the mechanical properties are highly dependent on the strain rate and temperature. The effects of various imperfections, such as the vacancy, crack, and void defects, on the mechanical properties were also studied. Results show that in the presence of void defects, the structure exhibited higher mechanical properties than when there were other defects. This phenomenon was found to be related to the decrease in the effective load transfer from aluminum to C₃N. Furthermore, by increasing the weight percent of the nanosheets up to 5%, the energy absorption rate increased by 25% compared to the pure aluminum. When C₃N was placed on top of the aluminum surface, the silicon nanoparticles were associated with a 35% energy adsorption by the nanocomposite. The results of this paper could be used to help understand and overcome some limitations in the fabrication of metallic nanocomposites with 2D material reinforcement.

This study unveils C₃N, a new material that serves as an excellent reinforcement to enhance the mechanical properties of aluminum using a molecular dynamics simulation method.

Fabrication of pH-responsive TA-keratin bio-composited hydrogels encapsulated with photoluminescent GO quantum dots for improved bacterial inhibition and healing efficacy in wound care management: In vivo wound evaluations

Wounds origins serious complications of lives of human beings which may leads to death. The important issue for the problem is infection during wound care management which delays wound healing process. These kinds of infections may be caused by the overuse or misuse of antibiotics, antidotes, usage of new drugs, not properly sterilized surgical instruments, not appropriate for pH level and imperfect wound dressing etc. during or after surgery. Hence in this report, antimicrobial action of pH responsive TA/KA composited hydrogel crosslinked with GO-QDs (TA/KA-GOQDs) using citric acid as cross-linker has been reported by demonstrating in-vitro and in-vivo studies for wound care management. The prepared samples of GOQDs, TA/KA hydrogel and TA/KA-GOQDs were characterized using FT-IR, XRD, SEM and TEM techniques. pH responsive hydrogel property of TA/KA was evaluated by swelling studies. In-vitro antibacterial studies was carried out by direct contact test method. Further, the prepared samples were tested in a wound healing model of rate with the wound of size 1.5 cm² for in-vivo studies. After 16 days of treatment, the prepared samples for wound healing causes 100% wound areas closure. Histological observations were made by MT and HE staining process which proves keratinocytes proliferation by biocompatible and biocomposited TA/KA-GOQDs. The pH responsive TA/KA-GOQDs proved as efficient wound healing agent by faster keratinocytes proliferation within a compact period.

Highly tunable doping in Ge quantum dots/graphene composite with distinct quantum dot growth evolution

Quantum dots/graphene (QDs/Gr) composites have become the research hotspot recently due to their unique synergistic effect as optical absorption material for next-generation electronic and optoelectronic devices. In this work, Ge QDs/Gr composite is prepared by a simple and effective ion-beam sputtering deposition technique. The intact growth evolution process is detailly investigated by means of the effect of Ge deposition amount, which will induce the enhanced crystallinity in QDs and the reduced defects in graphene. Moreover, a feasible and inspiring strategy to effectively tune doping in graphene by artificial control through changing the deposition amount of Ge atoms on graphene is demonstrated. In addition, charge transfer and interaction strength at the interface of Ge QD and graphene is influenced via the oxygen defect in the QD surface, which is consistent with field-effect transistor test and first-principle calculations. The p-doping characteristics of graphene decorated by Ge QDs may have significant application prospects in energy band engineering of graphene-based building blocks for graphene-based composite development and near-infrared detector applications.

Assembly of graphene nanoflake-quantum dot hybrids in aqueous solution and their performance in light-harvesting applications

Graphene nanoflakes and CdSe/ZnS quantum dots were covalently linked in environmentally friendly aqueous solution. Raman spectroscopy and photoluminescence studies, both in solution and on surfaces at the single nanohybrid level, showed evidence of charge transfer between the two nanostructures. The nanohybrids were further incorporated into solar cell devices, demonstrating their potential as light harvesting assemblies.

Nitrogen-doped graphene and graphene quantum dots: A review onsynthesis and applications in energy, sensors and environment

Doping of nitrogen is a promising strategy to modulate chemical, electronic, and structural functionalities of graphene (G)and graphene quantum dots (GQDs) for their outstanding properties in energy and environmental applications.This paper reviews various synthesis approaches of nitrogen-doped graphene (N-G) and nitrogen-doped graphene quantum dots (N-GQDs).;Thermal, ultrasonic, solvothermal, hydrothermal, and electron-beam methods have been applied to synthesize N-G and N-GQDs.These nitrogen-doped carbon materials are characterized to obtain their structural configurations in order to achieve better performance in their applications compared to only either graphene or graphene quantum dots.Both N-G and N-GQDs may be converted into functional materials by integrating with other compounds such as metal oxides/nitrides, polymers, and semiconductors.These functional materials demonstrate superior performance over N-G and N-GQDs materials.Examples of applications of N-G and N-GQDs include supercapacitors, batteries, sensors, fuel cells, solar cells, and photocatalyst.

Preparation of functionalized zirconium phosphate and its effect on the flame retardancy of silicone rubber

A novel functionalized zirconium phosphate was prepared and it effectively enhanced the flame retardancy of silicone rubber by a small amount.

Improved performance of optical phased arrays assisted by transparent graphene nanoheaters and air trenches

Improved performances of optical phased arrays have been achieved assisted by graphene nanoheaters and air trenches.

Efficient photocatalysis with graphene oxide/Ag/Ag2S–TiO2 nanocomposites under visible light irradiation

The photocatalytic reaction efficiency of GO/Ag/Ag₂S–TiO₂ nanorod arrays is 600% higher than that of a pure TiO₂ sample under visible light.