Silicene Nanosheets Research Articles

Novel silicene-mesoporous silica nanoparticles conjugated gemcitabine induced cellular apoptosis via upregulating NF-κB p65 nuclear translocation suppresses pancreatic cancer growth in vitro and in vivo

Pancreatic cancer’s high fatality rates stem from its resistance to systemic drug delivery and aggressive metastasis, limiting the efficacy of conventional treatments. In this study, two-dimensional ultrathin silicene nanosheets were initially synthesized and near-infrared-responsive two-dimensional silicene-mesoporous silica nanoparticles (SMSNs) were successfully constructed to load the clinically-approved conventional pancreatic cancer chemotherapeutic drug gemcitabine. Experiments on nanoparticle characterization show that they have excellent photothermal conversion ability and stability. Then silicene-mesoporous silica nanoparticles loaded with gemcitabine nanoparticles (SMSN@G NPs) were employed in localized photothermal therapy to control pancreatic tumor growth and achieve therapeutic effects. Our research confirmed the functionality of SMSN@G NPs through immunoblotting and apoptotic assays, demonstrating its capacity to enhance the nuclear translocation of the NF-κB p65, further affect the protein levels of apoptosis-related genes, induce the apoptosis of tumor cells, and ultimately inhibit the growth of the tumor. Additionally, the study assessed the inhibitory role of SMSN@G NPs on pancreatic neoplasm growth in vivo, revealing its excellent biocompatibility. SMSN@G NPs have a nice application prospect for anti-pancreatic tumors.

Electron Orbital Hybridization‐Enhanced Copper‐Nanocatalysis for Anti‐Infection

AbstractRecurrent bacterial infections, impenetrable microbial biofilms, and irremediable antibiotic resistance are the most perilous threats in orthopedic implant‐associated infections (IAIs). Recently, chemodynamic therapy (CDT) has been considered a promising therapy, while the clinical practices for existing CDT agents are limited by the low therapeutic efficiency in physiological circumstances. Herein, it is demonstrated that silica‐copper nanosheets (Si@Cu NSs) exhibit a combined therapeutic photothermal‐chemodynamic strategy for IAIs treatment with superior capacity and biocompatibility. This unique design endows the nanostructure with enhanced copper‐based Fenton‐like properties via p‐d orbital hybridization by incorporating copper nanoclusters (Cu NCs) on silicene nanosheets (Si NSs) matrix, integrating inherent photothermal performance of Si NSs with specific catalytic anti‐infection of Cu NCs against planktonic bacteria and biofilms both in vitro and in vivo. This study not only reveals the promising bio‐application prospects of 2D nanocatalytic biomaterials but also demonstrates the feasibility of constructing novel CDT agents by orbital hybridization for the catalytic treatment of IAIs.

A Comparative DFT Investigation on the Structural, Electric, Thermodynamic, and Optical Properties of the Pristine and Various Metals and Nonmetals (Li, Be, B, N, O, and F) Doped Graphene and Silicene Nanosheets

In recent times 2D nanosheets have come to the fore of the attention of researchers due to their unique properties. In this work, the comparative studies between graphene and silicene nanosheets before and after doping with different metals and nonmetals doping have been performed using a quantum mechanical approach, density functional theory (DFT) employing B3LYP functional along with the LanL2DZ. For Li, Be, B, N, O, and F dopants, periodic changes have been observed for both graphene and silicene nanosheets. Li doping causes increasing surface area and higher reactivity which suggests its feasibility in sensor development. On the other hand, N causes higher structural, and thermodynamical stability along with favorable electric properties. So, based on purposes, both Li and N-doped graphene and silicene nanosheets are suitable for real-life applications, especially in emerging technologies including supercapacitors, optoelectronic sensing devices, energy storage devices, and so on.

Recovery of Brine Resources Through Crown-Passivated Graphene, Silicene, and Boron Nitride Nanosheets Based on Machine-Learning Structural Predictions

Recovery of Brine Resources Through Crown-Passivated Graphene, Silicene, and Boron Nitride Nanosheets Based on Machine-Learning Structural Predictions

Engineering Copper-Containing Nanoparticles-Loaded Silicene Nanosheets with Triple Enzyme Mimicry Activities and Photothermal Effect for Promoting Bacteria-Infected Wound Healing.

Skin wounds accompaniedby bacterial infections threaten human health, and conventional antibiotic treatments are ineffective for drug-resistant bacterial infections and chronically infected wounds. The development of non-antibiotic-dependent therapeutics is highly desired but remains a challenging issue. Recently, 2D silicene nanosheets with considerable biocompatibility, biodegradability, and photothermal-conversion performance have received increasing attention in biomedical fields. Herein, copper-containing nanoparticles-loaded silicene (Cu2.8O@silicene-BSA) nanosheets with triple enzyme mimicry catalytic (peroxidase, catalase, and oxidase-like) activities and photothermal function are rationally designed and fabricated for efficient bacterial elimination, angiogenesis promotion, and accelerated wound healing. Cu2.8O@silicene-BSA nanosheets display excellent antibacterial activity through synergistic effects of reactive oxygen species generated from multiple catalytic reactions, intrinsic bactericidal activity of released Cu2+ ions, and photothermal effects, achieving high antibacterial efficiencies on methicillin-resistant Staphylococcus aureus (MRSA) of 99.1 ± 0.7% in vitro and 97.2 ± 1.6% in vivo. In addition, Cu2.8O@silicene-BSA nanosheets exhibit high biocompatibility for promoting human umbilical vein endothelial cell (HUVEC) proliferation and angiogenic differentiation. In vivo experiments reveal that Cu2.8O@silicene-BSA nanosheets with synergistic photothermal/chemodynamic therapeutics effectively accelerate MRSA-infected wound healing by eliminating bacteria, alleviating inflammation, boosting collagen deposition, and promoting angiogenesis. This research presents a promising strategy to engineer photothermal-assisted nanozyme catalysis for bacteria-invaded wound healing.

2D silicene nanosheets-loaded coating for combating implant-associated infection

Implant-associated infection (IAI) is an unsolved problem in orthopaedics. Current therapies, including antibiotics and surgical debridement, can lead severe clinical and financial burdens on patients. Therefore, there is an urgent need to reinforce the inherent antibacterial properties of implants. Recently, two-dimensional (2D) silicene nanosheets (SNs) have gained increasing attention in biomedical fields owing to their considerable biocompatibility, biodegradability and strong photothermal-conversion performance. Herein, a dual-functional photosensitive coating on a Ti substrate (denoted as TPSNs) was rationally fabricated for bacterial inhibition and osteogenesis promotion. For the first time, SNs were loaded onto the surface of implants. Hyperthermia generated by the SNs and polydopamine (PDA) coating under 808 nm laser irradiation achieved the in vitro anti-bacterial efficiency of 90.7 ± 2.4 % for S. aureus and 88.0 ± 5.8 % for E. coli, respectively. In addition, TPSNs exhibited promising biocompatibility for the promotion of BMSC (bone marrow mesenchymal stem cells) proliferation and spreading. The presence of silicon (Si) in TPSNs contributed to the improved osteogenic differentiation of BMSCs, elevating the expressions of RUNX2 and OCN. In animal experiments, the combination of TPSNs with photothermal therapy (PTT) achieved an anti-bacterial efficiency of 89.2 % ± 1.6 % against S. aureus. Furthermore, TPSNs significantly improved bone-implant osseointegration in vivo. Overall, the development of a dual-functional TPSNs coating provides a new strategy for combating IAI.

Multilayer Silicene Nanosheets Derived from a Recycling Process Using End-of-Life Solar Cells Producing a Silicene/Graphite Composite for Anodes in Lithium-Ion Batteries

Multilayer Silicene Nanosheets Derived from a Recycling Process Using End-of-Life Solar Cells Producing a Silicene/Graphite Composite for Anodes in Lithium-Ion Batteries

2D silicene nanosheets for the detection of DNA nucleobases for genetic biomarker: a DFT study

2D silicene nanosheets for the detection of DNA nucleobases for genetic biomarker: a DFT study

Effect of different exfoliation solvents on the saturable absorption properties of germanene and silicene nanosheets prepared by the liquid-phase exfoliation

Germanene and silicene, as graphene analogs of germanium and silicon, have similar structures and properties to graphene, exhibiting exciting nonlinear optical absorption properties. Herein, 2D germanium nanosheets and 2D silicon nanosheets were successfully prepared by liquid-phase exfoliation method using ethanol, isopropanol, and N-methylpyrrolidone as exfoliation solvents, respectively. The dual-arm detection technique was used to systematically research the saturable absorption properties of the nanosheets prepared with different exfoliation solvents from the same material under the excitation of a picosecond pulsed laser. The nonlinear experiment results show that the saturable absorption properties of 2D germanium nanosheets and 2D silicon nanosheets are affected by different exfoliation solvents, and these influences from different exfoliation solvents have their advantages and disadvantages. In addition, the difference in saturable absorption properties of germanium nanosheets and silicon nanosheets under the same experimental conditions is compared. The saturable absorption behavior of germanium nanosheets in the near-infrared band is better than that in the visible band, while the silicon nanosheets have stronger saturable absorption behavior in the visible band. Both germanium nanosheets and silicon nanosheets exhibit superior SA properties, which have a wide range of application prospects in generating ultrashort pulses in ultrafast lasers as saturable absorbers. Our work provides a new idea for the study of nonlinear absorption properties of 2D materials and provides a reference and basis for further optimization and improvement of the properties parameters of saturable absorbers. Additionally, it inspires further research on the nonlinear absorption properties of semiconductor materials.

Biocompatible, antibacterial, and antifungal two-dimensional silicene nanosheets with a honeycomb hexagonal structure

Biocompatible, antibacterial, and antifungal two-dimensional silicene nanosheets with a honeycomb hexagonal structure

Cage-like Silicene/CNT Microspheres Synthesized by a Topochemical Reaction as Anodes for Enhanced Stable Lithium-Ion Batteries

Silicene has recently received increasing attention as an anode material in lithium-ion batteries (LIBs) due to its unique architectural properties. However, the synthesis of silicene still remains challenging, which limits its practical applications. In this work, silicene nanosheets with multilayer stacks are synthesized by the topochemical method and successfully combined with carbon nanotubes (CNTs) to form a cage-like structure composite. Benefiting from the hierarchical structure and two-dimensional active material, the cage-like silicene/CNTs increases the ionic and electric conductivity while reducing the volume expansion and relieving swelling stress. In addition, calculation also indicates a lower diffusion energy barrier of lithium ions in silicene than that in bulk silicon, which ultimately enhances the rate and cycling performance of the battery. The as-obtained electrodes exhibit a capacity of 690 mA h g–1 at 1 A g–1 after 500 cycles. This work not only introduces a facile topochemical method to prepare materials with two-dimensional multilayer silicene but also provides a new strategy for the application of silicene in LIBs.

Size-controllable crown ether-embedded 2D nanosheets for the host-guest ion segregation and recovery: Insights from DFT simulations

The recovery of lithium ion from spent lithium sources and from seawater is a strategic way of complementing the existing natural sources to meet the rapid growth in demand. Crown ethers have shown remarkable selectivity in the host-guest extraction of several metal cations. Recent studies have shown that the macrocyclic polyether rings exhibit poor selectivity to lithium when competing with other metals of high abundance and similar cationic size. This study thus presents a strategy to improve the selective extraction of lithium on crown-embedded 2D materials using first principles density functional theory (DFT) simulations. Several ion transmission channels of 9-crown-3, 12-crown-4, 15-crown-5 and 18-crown-6 were created on graphene, hexagonal boron nitride and silicene nanosheets. Compared to the pristine crown ethers, the crown-embedded 2D materials exhibit rapid charge transfer, superior host-guest dipole-dipole interactions and higher Li+/Mg2+, Li+/Na+, Li+/K+ and Li+/Ca2+ selectivities while maintaining the properties of the 2D materials. Adsorption energies, Eads of −262.8, −605.1, −566.4 and −231.0 kcal/mol were calculated for the adsorption of Li+ ion on 12-crown-4, g-14-crown-4, b-14-crown-4 and s-14-crown-4, respectively. The sp3-hybridized low-buckled crown-4 passivated silicene nanosheet, having a narrower bandgap of 0.588 eV demonstrates the rapid diffusion of Li+ ion while slowing down other cations. The present study provides insights on the creation of ion-channels within silicene nanosheet to promote the host-guest selective recovery of lithium in the presence of abundant interfering ions such as in seawater, a prospect which could serve as a feasible strategy for meeting the rapidly thriving energy demand of the metal atoms.

Two-dimensional silicene photodynamic tumor-targeting nanomedicine.

Since the innovative development of photosensitizers (PSs) is pivotal prerequisite for the successful clinical translation of photodynamic therapy (PDT), the unresolved challenges of classical PSs such as photobleaching, poor bioavailability, lack of tumor selectivity encourage the exploitation of new-generation PSs. In this work, we develop silicene nanosheets with unparalleled physiochemical nature and intriguing biocompatibility as the distinct two-dimensional (2D) nanoscale photosensitizer based on the mechanism of wet-chemical synthetic approach to achieve effective PDT-based tumor nanotherapy. The generation capacities of singlet oxygen (1O2) in different atmospheres have been systematically explored in depth. Furthermore, the conjunction of c (RGDyC) onto 2D silicene nanosheets (denoted as SRGD) endows the SRGD nanomedicines with specific targeting properties to αvβ3 integrin-overexpressed cancer cells, accomplishing in vivo and in vitro potent tumor growth inhibition efficiency. More notably, the excellent light absorption capacity of 2D silicene enables the tumor-specific photoacoustic imaging for potentiating the therapeutic guidance and monitoring. This paradigm can inspire the future design and applications of 2D silicene-based cancer-theranostic nanoplatform in biology and medicine.

Silicene nanosheets intercalated in slightly defective epitaxial graphene on a 4H-SiC(0001) substrate

In the last years, epitaxial graphene (epi-Gr) demonstrated to be an excellent substrate for the synthesis of epitaxial or intercalated two dimensional (2D) materials. Among 2D materials, silicene has been for a long time a dream for the scientific community, for its importance both from the fundamental and the application point of view. Despite the theoretical prediction of silicene energetic viability, experimentally the substrate proved to play a fundamental role in the Si atom adsorption process leading, in case of metal substrates, to a mixed phase formation and, for van der Waals chemical inert substrates, to Si atom intercalation even at room temperature. Such an intercalation has been associated to the presence of surface defects. Very recently it has been shown that hundreds of nanometer area quasi-free standing silicene can be grown on top of an almost ideal epi-Gr layer synthesized on 6H-SiC substrate. In the present paper, using scanning tunneling microscopy and Raman analysis, we demonstrate that a non-ideal (slightly defective) epi-Gr network obtained by thermal decomposition of Si-terminated 4H-SiC(0001) enables the Si atom penetration forming intercalated silicene nanosheets at room temperature, thus opening a path towards controlled intercalation of silicon atoms through epi-Gr and formation of silicene nanosheets for future applications in nanotechnology.

A DFT investigation on the mechanical and structural properties of silicene nanosheets under doping of transition metals

A DFT investigation on the mechanical and structural properties of silicene nanosheets under doping of transition metals

Engineering 2D Silicene-Based Mesoporous Nanomedicine for In Vivo Near-Infrared-Triggered Analgesia.

The utilization of local anesthetics for postoperative analgesia represents an effective approach, but generally suffers from short half‐lives and brachychronic local neurotoxicity. A desirable anesthetic with controllable and sustainable drug‐releasing performance for adequate analgesia effect is highly required. In this work, the core/shell‐structured two‐dimenional (2D) silicene nanosheets coated with mesoporous silica layer (abbreviated as Silicene@MSNs) have been rationally constructed as localized drug‐delivery system in sciatic nerve block to achieve on‐demand release of loaded ropivacaine (RP) in mesoporous silica layer for local analgesia. Based on the specific photothermal performance of 2D silicene core, this local anesthesia system can be triggered by near‐infrared laser to release the loaded RP, resulting in on‐demand and long‐lasting regional anesthesia. The analgesia effect is assessed by pain behavior tests, which demonstrates that the RP‐loaded Silicene@MSNs core/shell nanosystem behaves almost five times longer analgesia effect than free RP. Furthermore, the activation of pain‐related neurons in nerve conduction pathways is tested to explore the underlying analgesia mechanism, revealing that the designed nanosystem can improve the pain threshold, reduce the activation of neurons in dorsal root ganglion and excitability in spinal substantia gelatinosa neurons. This designed anesthetic nanomedicine provides a facile but effective methodology for long‐lasting regional anesthesia.

Silicene nanosheets as support fillers for thin film composite forward osmosis membranes

Development of membranes with enhanced separation and transport properties remains crucial for the advancement of forward osmosis (FO). Herein, a novel thin film composite (TFC) FO membrane with silicene-loaded polysulfone support (SN) is reported. Silicene loading was varied to obtain different SNs grown with polyamide (PA) layers to afford TFC-SN FO membranes. Characterization results reveal that optimal silicene loading (0.25 wt%) produced the most porous and most hydrophilic SN0.25 with finger-like pore structures. Low silicene loading showed minimal impact, whereas, excessive addition resulted in aggregation which diminished its effect in SN. Meanwhile, silicene had no influence on PA layer formation as all TFC-SNs registered similar solute permeability coefficient B = 0.14–0.16 LMH. On the other hand, TFC-SN0.25 achieved the highest water permeability coefficient A = 1.56 LMH bar−1 attributable to the favorable properties of SN0.25. TFC-SN0.25 also exhibited the lowest structural parameter S = 334 μm, which explains its superior FO performance relative to other TFC-SNs. Results from FO runs indicate that internal concentration polarization was reduced by 27.5–33% in TFC-SN0.25 compared with the control (TFC-SN0). FO runs in simulated low salinity water and seawater feed highlight the potential of TFC-SN0.25 for desalination. The developed TFC-SN0.25 can be repeatedly used and deliver consistent Jv values. Overall findings demonstrate the benefits of silicene for improved performance of TFC FO membranes.

Nontoxic silicene photothermal agents with high near-infrared absorption for disassembly of Alzheimer’s amyloid‑β fibrils

The disassembly and eliminating the amyloid-β (Aβ) aggregates has become an effective way to treat Alzheimer’s disease (AD). Herein, for the first time, the near-infrared (NIR) activated silicene nanosheets (SNSs) have been identified as an effective nontoxic photothermal conversion agent for irreversibly disassembly of the Aβ33–42 aggregates. The SNSs synthesized by a combination of mild oxidation method and liquid exfoliation method possess good biocompatibility and biodegradability, and high near-infrared photothermal conversion capabilities. Under NIR light, the SNSs could disassemble the large and dense Aβ33–42 mature fibrils into short fibrils and even form thin films, leading to the degradation rate of 96.47%. The circular dichroism spectrum, fluorescent spectra, and nanostructure were analyzed to monitor the photothermal degradation of mature Aβ33–42 fibrils for elaborating the mechanism beneath. This study might provide a clue for developing potential therapeutic strategy for AD and related neurodegenerative diseases.

Silicene/poly(N-isopropylacrylamide) smart hydrogels as remote light-controlled switches

Smart hydrogels with good flexibility and biocompatibility have been widely used. The common near-infrared (NIR) photothermal agents are facing a trade-off between good photothermal-conversion efficiency and high biocompatibility. Therefore, developing new metal-free photothermal agents with low cost, high biocompatibility and excellent phase stability is still in urgent need. In this study, we successfully combined poly(N-isopropylacrylamide) (PNIPAM) with the two-dimensional (2D) silicene nanosheets via the in situ polymerization method. Attributed to the thermal-responsive nature of PNIPAM and the excellent photothermal properties of 2D silicene, the obtained silicene/PNIPAM composite hydrogels exhibited dual thermal and NIR responsive properties. This smart hydrogel showed rapid, reversible and repeatable NIR light-responsive behaviors. The volume of this smart hydrogels can shrink significantly under NIR irradiation and recover to its original size without the NIR irradiation. Remote near-infrared light-controlled microfluidic pipelines and electronic switches based on obtained silicene/PNIPAM composite hydrogels were also demonstrated. This work significantly broadens the application prospects of silicene-based hydrogels in remote light-controlled devices.

A DFT investigation on the mechanical and structural properties of halogen- and metal-adsorbed silicene nanosheets

Herein, the effects of halogen and metal atomic adsorption on the mechanical and structural characteristics of silicene are studied using density functional theory (DFT) calculations. Cl, Br, Au, Ca, Ga, Li, and Na atoms are selected as the adsorption atoms. Moreover, the phonon dispersion and electron localization function are investigated to show the stability of considered nanostructures and to visualize the bonding properties, respectively. It is shown that the adsorption leads to decreasing the elastic and bulk moduli of some structures, while it increases them in some other structures. It is seen that except for Ca-adsorbed nanosheet, both the elastic and bulk moduli of all other structures decrease after adsorption. Furthermore, the isotropic behavior of all the studied nanosheets is indicated. The plastic behavior is also analyzed. It is revealed that the second critical strain of all nanosheets, except for SiBr and SiCl, decreases under uniaxial loading. However, under biaxial loading conditions, the second critical strain of Au-, Ca-, and Ga-adsorbed structures decreases, while in other structures (SiBr, SiCl, SiLi, and SiNa) the adsorption increases the yield strain.