Fabrication of multi-shell coated silicon nanoparticles via in-situ electroless deposition as high performance anodes for lithium ion batteries

Si-based materials have been extensively studied because of their high theoretical capacity,low working potential,and abundant reserves,but serious initial irreversible capacity loss and poor cyclic performance resulting from large volume change of Si during lithiation and delithiation processes restrict their widespread application.Herein,we report the preparation of multi-shell coated Si(DS-Si)nanocomposites by in-situ electroless deposition method using Si granules as the active materials and copper sulfate as Cu sources.The ratio of Si and Cu was readily tuned by varying the concentration of copper sulfate.The multi-shell(Cu@CuxSi/SiO2)coating on Si surface promotes the formation of robust and dense SEI films and the transportation of electron.Thus,the obtained DS-Si composites exhibit an initial coulombic efficiency of 86.2%,a capacity of 1636 mAh g^-1 after 100 discharge-charge cycles at 840 mA g^-1,and an average charge capacity of 1493 mAh g^-1 at 4200 mA g^-1.This study provides a low-cost and large-scale approach to the preparation of nanostructured Si-metal composites anodes with good electrochemical performance for lithium ion batteries.

Determination of Particle Sizes and Crystalline Phases on Colloidal Silicon Nanoparticle Suspensions

Particle size and crystallinity of silicon nanoparticles were determined by analyzing the optical extinction spectra of colloidal suspensions. Experimental results from these colloids were anaiyzed using Mie theory in connection with effective medium theory, in order to determine particle sizes and their internal structure with the simple technique of optical transmission spectroscopy. By modeling an effective refractive index for the particles, the crystalline volume fraction can be extracted from extinction spectra in addition to information about the size. The crystalline volume fraction determined in this way were used to calibrate the ratio of the Raman cross sections for nanocrystalline and amorphous silicon, which was found to be σc./σa = 0.66

Potential Alzheimer’s disease therapeutic nano-platform: Discovery of amyloid-beta plaque disaggregating agent and brain-targeted delivery system using porous silicon nanoparticles

There has been a lot of basic and clinical research on Alzheimer’s disease(AD)over the last 100 years,but its mechanisms and treatments have not been fully clarified.Despite some controversies,the amyloid-beta hypothesis is one of the most widely accepted causes of AD.In this study,we disclose a new amyloid-beta plaque disaggregating agent and an AD brain-targeted delivery system using porous silicon nanoparticles(pSiNPs)as a therapeutic nano-platform to overcome AD.We hypothesized that the negatively charged sulfonic acid functional group could disaggregate plaques and construct a chemical library.As a result of the in vitro assay of amyloid plaques and library screening,we confirmed that 6-amino-2-naphthalenesulfonic acid(ANA)showed the highest efficacy for plaque disaggregation as a hit compound.To confirm the targeted delivery of ANA to the AD brain,a nano-platform was created using porous silicon nanoparticles(pSiNPs)with ANA loaded into the pore of pSiNPs and biotin-polyethylene glycol(PEG)surface functionalization.The resulting nano-formulation,named Biotin-CaCl2-ANA-pSiNPs(BCAP),delivered a large amount of ANA to the AD brain and ameliorated memory impairment of the AD mouse model through the disaggregation of amyloid plaques in the brain.This study presents a new bioactive small molecule for amyloid plaque disaggregation and its promising therapeutic nano-platform for AD brain-targeted delivery.

Fluorescent silicon nanoparticles-based nanotheranostic agents for rapid diagnosis and treatment of bacteria-induced keratitis

Recommended as a medical emergency,infectious keratitis with an acute and rapid disease progression can lead to serious damage of vision and even blindness.Herein,we present a kind of theranostic agents,which are made of vancomycin(Van)-modified fluorescent silicon nanoparticles(SiNPs-Van),enabling rapid and non-invasive diagnosis and treatment of Gram-positive bacteria-induced keratitis in a simultaneous manner.Typically,the resultant SiNPs-Van nanoagents have an ability of imaging bacteria in a short time both in vitro(5 min)and in vivo(10 min),making them an efficacious diagnostic agent for the detection of bacterial keratitis.In addition,the SiNPs-Van feature distinct antimicrobial activity,with superior activity of 92.5%at a concentration of 0.5 ng/mL against Staphylococcus aureus(S.aureus);comparatively,the antimicrobial rate of free vancomycin is 23.3%at the same concentration.We further explore the SiNPs-Van agents as eye drops for therapy of S.aureus-induced bacterial keratitis on rat model.Represented by slit-lamp scores,the keratitis severity of SiNPs-Van-treated corneas is 3.4,which is 59.6%and 77.3%slighter than vancomycin-(8.2 score)and PBS-treated corneas(15.0 score),respectively.The infected corneas recover to normal(1 score)after 7-d of SiNPs-Van treatment.Above results suggest that the SiNPs-Van could serve as a new kind of high-quality nanotheranostic agents,especially suitable for simultaneous diagnosis and therapy of Gram-positive bacteria keratitis.

Antiviral adsorption activity of porous silicon nanoparticles against different pathogenic human viruses

New viral infections,due to their rapid spread,lack of effective antiviral drugs and vaccines,kill millions of people every year.The global pandemic SARS-CoV-2 in 2019-2021 has shown that new strains of viruses can widespread very quickly,causing disease and death,with significant socio-economic consequences.Therefore,the search for new methods of combating different pathogenic viruses is an urgent task,and strategies based on nanoparticles are of significant interest.This work demonstrates the antiviral adsorption(virucidal)efficacy of nanoparticles of porous silicon(PSi NPs)against various enveloped and non-enveloped pathogenic human viruses,such as Influenza A virus,Poliovirus,Human immunodeficiency virus,West Nile virus,and Hepatitis virus.PSi NPs sized 60 nm with the average pore diameter of 2 nm and specific surface area of 200 m^(2)/g were obtained by ball-milling of electrochemically-etched microporous silicon films.After interaction with PSi NPs,a strong suppression of the infectious activity of the virus-contaminated fluid was observed,which was manifested in a decrease in the infectious titer of all studied types of viruses by approximately 104 times,and corresponded to an inactivation of 99.99%viruses in vitro.This sorption capacity of PSi NPs is possible due to their microporous structure and huge specific surface area,which ensures efficient capture of virions,as confirmed by ELISA analysis,dynamic light scattering measurements and transmission electron microscopy images.The results obtained indicate the great potential of using PSi NPs as universal viral sorbents and disinfectants for the detection and treatment of viral diseases.

The in vivo targeted molecular imaging of fluorescent silicon nanoparticles in Caenorhabditis elegans

Owing to their unique optical properties （e.g., bright fluorescence coupled with strong photostability） and negligible toxicity, fluorescent silicon nanoparticles （SiNPs） have been demonstrated to be promising probes for bioimaging analysis. Herein, we describe the use of Caenorhabditis elegans （C. elegans） as an animal model to investigate the in vivo behavior and molecular imaging capacity of ultrasmall fluorescent SiNPs （e.g., - 3.9 ± 0.4 nm）. Our studies show that （1） the internalized SiNPs do not affect the morphology and physiology of the worms, suggesting the superior biocompatibility of SiNPs in live organisms; （2） the internalized SiNPs cannot cross the basement membrane of C. elegans tissues and they display limited diffusion ability in vivo, providing the possibility of their use as nanoprobes for specific tissue imaging studies in intact animals; （3） more than 80% of the fluorescence signal of internalized SiNPs remains even after 120 min of continuous laser bleaching, whereas only - 20% of the signal intensity of mCherry or cadmium telluride quantum dots remains under the same condition, indicating the robust photostability of SiNPs in live organisms; and （4） cydic RGD-peptide-conjugated SiNPs can specifically label muscle attachment structures in live C. elegans, which is the first proof-of-concept example of SiNPs for targeted molecular imaging in these live worms. These finding raise exciting opportunities for the design of high-quality SiNP-based fluorescent probes for long-term and real-time tracking of biological events in vivo.

Ginseng ameliorates pulmonary toxicity induced by silicon dioxide nanoparticles in rats

Objective:To investigate the protective and therapeutic role of ginseng against silicon dioxide nanoparticles(SiO2NPs)-induced toxicity in the lungs.Methods:Sixty male rats were divided into five groups(n=12/group);group 1 was used as a control,group 2 received ginseng,group 3 was treated with SiO2NPs,and group 4 was pretreated with ginseng one week before SiO2NPs,while group 5 was given SiO2NPs one week before supplementation with ginseng.Animals were treated with both ginseng and SiO2NPs orally for five weeks.Real-time PCR was used to measure gene expression.Besides,DNA damage and cell cycle changes were determined by comet assay and flow cytometry,respectively.Histological study was also done to assess the effect of ginseng on SiO2NPs-induced toxicity.Results:SiO2NPs increased lipid peroxidation and decreased the activities of antioxidant enzymes.SiO2NPs induced apoptosis in lung tissues as revealed by upregulation of Bax and caspase 3 and downregulation of Bcl-2 as well as the induction of DNA damage.SiO2NPs also caused inflammation as indicated by upregulation of the inflammation-related genes[interleukin 1 beta(IL-1β),tumor necrosis factor-alpha(TNF-α),nuclear factor kappa B(NF-κB),cyclooxygenase 2(COX2),and transforming growth factor-beta 1(TGFβ1)]as well as cell cycle arrest in the G0/G1 phase of lung cells.Moreover,histopathological examination proved the biochemical and molecular perturbations that occurred due to SiO2NPs toxicity.However,ginseng alleviated SiO2NPs-induced toxicity in rat lung.Conclusions:Ginseng has a potent preventive and therapeutic effect and could be used in the treatment of SiO2NPs-induced pulmonary toxicity.

Application of two forms of silicon and their impact on the postharvest and the content of bioactive compounds in cucumber(Cucumis sativus L.)fruits

The metabolic activity of the fruits continues even after harvest,which results in the loss of bioactive compounds,a decrease in the quality of the fruits,softening and browning,among other negative effects.The use of certain elements such as silicon can improve postharvest quality,since it is involved in the metabolic,physiological and structural activity of plants,moreover can increase the quality of the fruits.In addition,nanotechnology has had a positive impact on crop yield,nutritional value,fruit quality and can improve antioxidant activity.For these reasons,the use of beneficial elements such as silicon in the form of nanoparticles can be a viable option to improve the characteristics of the fruits.In the present study was evaluated the application of potassium silicate(125,250 and 500 mg L^(−1))and SiO_(2) nanoparticles(125,250 and 500 mg L^(−1))during the development of the crop.The results showed that the application of silicon(potassium silicate and silicon nanoparticles)increased the content of total soluble solids(up to 15.6%higher than control),titratable acidity(up to 38.8%higher than control),vitamin C(up to 78.2%higher than control),phenols(up to 22%higher than control),flavonoids(up to 64.6%higher than control),and antioxidant activity in lipophilic compounds(up to 56.2%higher than control).This study suggests that the use of silicon can be a good option to increase the content of bioactive compounds in cucumber fruits when they are applied during the development of the crop.

Synthesis and characterization of Fe_3O_4@SiO_2 magnetic composite nanoparticles by a one-pot process

Fe3O4@SiO2 core–shell composite nanoparticles were successfully prepared by a one-pot process. Tetraethyl-orthosilicate was used as a surfactant to synthesize Fe3O4@SiO2 core–shell structures from prepared Fe3O4 nanoparticles. The properties of the Fe3O4 and Fe3O4@SiO2 composite nanoparticles were studied by X-ray diffraction, transmission electron microscopy, energy dispersive spectroscopy, and Fourier transform infrared spectroscopy. The prepared Fe3O4 particles were approximately 12 nm in size, and the thickness of the SiO2 coating was approximately 4 nm. The magnetic properties were studied by vibrating sample magnetometry. The results show that the maximum saturation magnetization of the Fe3O4@SiO2 powder（34.85 A·m^2·kg^–1） was markedly lower than that of the Fe3O4 powder（79.55 A·m^2·kg^–1）, which demonstrates that Fe3O4 was successfully wrapped by SiO2. The Fe3O4@SiO2 composite nanoparticles have broad prospects in biomedical applications; thus, our next study will apply them in magnetic resonance imaging.

Synthesis and characterization of high strength polyimide/silicon nitride nanocomposites with enhanced thermal and hydrophobic properties

Polyimide(PI)composite films were synthesized incorporating amino modified silicon nitride(Si_(3)N_(4))nanoparticles into PI matrix via in situ polymerization technique.The mechanical and thermal performances as well as the hydrophobic properties of the as prepared composite films were investigated with respect to the dosage of the filler in the PI matrix.According to Thermogravimetric(TGA)analysis,meaningful improvements were achieved in T5(5%weight loss temperature)and T10(10%weight loss temperature)up to 54.1℃ and 52.4℃,respectively when amino functionalized nano Si_(3)N_(4) particles were introduced into the PI matrix.The differential scanning calorimetry(DSC)results revealed that the glass transition temperature(Tg)of the composites was considerably enhanced up to 49.7℃ when amino functionalized Si_(3)N_(4) nanoparticles were incorporated in the PI matrix.Compared to the neat PI,the PI/Si_(3)N_(4) nanocomposites exhibited very high improvement in the tensile strength as well as Young’s modulus up to 105.4%and 138.3%,respectively.Compared to the neat PI,the composites demonstrated highly decreased water absorption behavior which showed about 68.1%enhancement as the content of the nanoparticles was increased to 10 wt%.The SEM(Scanning electron microscope)images confirmed that the enhanced thermal,mechanical and water proof properties are essentially attributed to the improved compatibility of the filler with the matrix and hence,enhanced distribution inside the matrix because of the amino groups on the surface of Si_(3)N_(4) nanoparticles obtained from surface functionalization.

Anomalous pressure-dependence in surface-modified silicon-derived nanoparticles

Surfaces can significantly alter the optical properties of nanomaterials,but they are difficult to control and their roles are hard to understand in highly reactive materials such as silicon nanomaterials.In this work,we investigate the role of the surface in controlling the optical transitions in highly luminescent silicon-derived nanoparticles.By combining high-pressure and low-temperature experiments,we experimentally correlate the anomalously intense and narrow transitions in the UV range with the surface oxides,while the visible transition and the photoluminescence(PL)are verified to originate from the Si-ligand charge transfer band.We find that the high-pressure absorption and PL depends on the rigidity of the surface ligand.This indicates that the surface plays a dominant role on the optical properties of these silicon-derived nanoparticles,and is different than other semiconductor nanomaterials,in which pressure-dependent optical transitions depend on lattice strain or phase transformations.This work presents a comprehensive understanding of the optical transitions and the effect of surface ligands and surface oxidation in these highly luminescent Si-derived nanoparticles.The new insight into the oxidation-activated and ligand-mediated transitions,and the pressure-dependent PL may help with engineering the band structure of other highly-reactive optical nanomaterials.

Enhancement of R6G fluorescence by N-type porous silicon deposited with gold nanoparticles

By the electrochemical anodization method,we achieve the single-layer macroporous silicon on the N-type silicon,and prepare gold nanoparticles with sodium citrate reduction method. Through injecting the gold nanoparticles into the porous silicon by immersion,the fluorescence quenching mechanism of porous silicon influenced by gold nanoparticles is analyzed. Then the macroporous silicon deposited with gold nanoparticles is utilized to enhance the fluorescence of rhodamine 6G(R6G). It is found that when the macroporous silicon is deposited with gold nanoparticles for 6 h,the maximum fluorescence enhancement of R6G(about ten times) can be realized. The N-type porous silicon deposited with gold nanoparticles can be an excellent substrate for fluorescence detection.

Traditional Chinese medicine molecule-assisted chemical synthesis of fluorescent anti-cancer silicon nanoparUcles

Fluorescent silicon （Si） nanopartides （SiNPs） hold great promise for innumerable biological and biomedical applications owing to their unique optical properties and negligible toxicity. In this article, we present a new traditional Chinese medicine （TCM） molecule-assisted chemical synthetic strateg36 suitable for the production of multifunctional small-sized （diameter： - 3.7 nm） SiNPs in a facile and rapid （- 10 min） manner. Of particular significance, the resultant SiNPs simultaneously exhibited robust and stable fluorescence （photoluminescence quantum yield （PLQY）： ~ 15%）, as well as intrinsic anti-cancer efficacy with excellent selectivity toward cancer cells. Taking advantage of these unique merits, we further employed these novel fluorescent anti-cancer SiNPs （AC-SiNPs） for the fluorescence tracking and treatment of tumors, demonstrating long-term （~ 18 days） inhibition of tumor growth in tumor-bearing mice. Consequently, we believe this new TCM-assisted chemical synthetic method is highly attractive for designing silicon nanostructures featuring multiple functionalities, and we suggest these AC-SiNPs as novel promising tools for providing visual evidence of TCM-based cancer treatment.

Doping Silicon Wafers with Boron by Use of Silicon Paste

In this work we introduce recently developed silicon-paste-enabled p-type doping for silicon. Boron-doped silicon nanoparticles are synthesized by a plasma approach. They are then dispersed in solvents to form silicon paste. Silicon paste is screen-printed at the surface of silicon wafers. By annealing, boron atoms in silicon paste diffuse into silicon wafers. Chemical analysis is employed to obtain the concentrations of boron in silicon nanoparticles. The successful doping of silicon wafers with boron is evidenced by secondary ion mass spectroscopy （SIMS） and sheet resistance measurements.

Silicon-based nanoprobes cross the blood–brain barrier for photothermal therapy of glioblastoma

Traditional photothermal agents of indocyanine green(ICG)have poor stability,short circulation time,and poor brain permeability due to the blood–brain barrier(BBB),greatly impairing their therapeutic efficacy in glioblastoma(GBM).Herein,we develop a novel kind of SiNPs-based nanoprobes to bypass the BBB for photothermal therapy of GBM.Typically,the SiNPs-based nanoprobes are composed of the particle itself,the BBB-targeting ligand of glucosamine(G),and the therapeutic agent of ICG.We demonstrate that the as-synthesized nanoprobes could cross the BBB through glucose transporter-1(GLUT1)-mediated transcytosis,followed by accumulation at GBM tissues in mice.Compared with free ICG,G-ICG-SiNPs show stronger stability(for example,the fluorescence intensity of G-ICG-SiNPs loaded with the same dose of ICG decays by 34.6%after 25 days of storage,while the fluorescence intensity of ICG decays by 99.5%under the same conditions).Furthermore,the blood circulation time of G-ICG-SiNPs increases by about 17.3-fold compared with their ICG counterparts.After injection of the therapeutic agents into the GBM-bearing mice,GBM-surface temperature rises to 45.3℃in G-ICG-SiNPs group after 5-min 808 nm irradiation but climbs only to 36.1℃in equivalent ICG group under the identical conditions,indicating the superior photothermal effects of GICG-SiNPs in vivo.

Improved Photovoltaic Performance of MEH-PPV/PCBM Solar Cells via Incorporation of Si Nanocrystals

We have studied the effect of silicon nanocrystals （SiNCs） as a third component on performance of organic bulk heterojunction solar cells composed of poly[2-methoxy,5-（2＇-ethylhexyloxy）-l,4-phenylene vinylene] （MEH- PPV）：[6,6]-phenyI-C61-butyric acid methyl ester （PCBM） blend film. By adding suitable amounts of SiNCs into MEH-PPV：PCBM blend, the device performance such as external quantum efficiency, short circuit current density （Js（）, and power conversion efficiency （PCE） improved. Incorporation of 2.5% SiNCs in the blend led to 13.6% improvement of Jsc, which in turn resulted in 18% improvement of PCE up to 2.28%. The improved performance was mainly due to the improvements both in the charge generation from the interface of MEH-PPV/SiNCs and the charge collection at the cathode.

Fluorescent quantum dots for microbial imaging

Quantum dots（QDs）, with several unique optical and chemical features, are becoming desirable fluorescent tags for the biological applications that require long-term and highly sensitive imaging.Besides, the conjugation of various functional biomolecules to QDs has enabled wide applications of QDs in biological imaging. This review focuses on the following four types of QDs： semiconductor quantum dots（semiconductor QDs）, carbon nanodots（CDs）, silicon quantum dots（SiQDs）, and polymer dots（Pdots）, and summarizes the recent advancements of using these QDs in imaging microorganisms including viruses, bacteria, and fungi. We hope that this review will promote the development of new fluorescent QDs for microbial imaging and extend the applications of QD-based imaging techniques in cell biology and beyond.

Long-term fundus fluorescence angiography and real-time diagnosis of retinal diseases in non-human primate-animal models

Fluorescein angiography(FA)is a standard imaging modality for evaluating vascular abnormalities in retina-related diseases,which is recognized as the major cause of vision loss.Long-term and real-time fundus angiography is of great importance in preclinical research,nevertheless remaining big challenges up to present.In this study,we demonstrate that long-term fluorescence imaging of retinal vessels is enabled through a kind of fluorescent nanoagents,which is made of small-sized(hydrodynamic diameter:∼3 nm)silicon nanoparticles(SiNPs)featuring strong fluorescence,robust photostability,lengthened blood residency and negligible toxicity.In particular,the presented SiNPs-based nanoagents are capable of imaging retinal capillaries in∼10 min,which is around 10-fold longer than that(∼1 min)of fluorescein sodium(FS,known as the most widely used contrast agents for FA in clinic).Taking cynomolgus macaques as non-human primate-animal model,we further demonstrate the feasibility of real-time diagnosis of retinal diseases(e.g.,age-related macular degeneration(AMD))through dynamic monitoring of vascular dysfunction.

Characterization of the nanosized porous structure of black Si solar cells fabricated via a screen printing process

A silicon（Si） surface with a nanosized porous structure was formed via simple wet chemical etching catalyzed by gold（Au） nanoparticles on p-type Cz-Si（100）.The average reflectivity from 300 to 1200 nm was less than 1.5%.Black Si solar cells were then fabricated using a conventional production process.The results reflected the output characteristics of the cells fabricated using different etching depths and emitter dopant profiles.Heavier dopants and shallower etching depths should be adopted to optimize the black Si solar cell output characteristics. The efficiency at the optimized etching time and dopant profile was 12.17%.However,surface passivation and electrode contact due to the nanosized porous surface structure are still obstacles to obtaining high conversion efficiency for the black Si solar cells.

Answer to comments on “Fabrication and photovoltaic conversion enhancement of graphene/n-Si Schottky barrier solar cells by electrophoretic deposition”

Here,we reply to comments by Valentic et al.on our paper published in Electrochimica Acta（2014,130：279）.They commented that Au nanoparticles played the dominant role on the whole cell＇s performances in our improved graphene/Si solar cell.We argued that our devices are Au-doped graphene/n-Si Schottky barrier devices,not Au nanoparticles（film）/n-Si Schottky barrier devices.During the doping process,most of the Au nanopatricles covered the surfaces of the graphene.Schottky barriers between doped graphene and n-Si dominate the total cells properties.Through doping,by adjusting and tailoring the Fermi level of the graphene,the Fermi level of n-Si can be shifted down in the graphene/Si Schottky barrier cell.They also argued that the instability of our devices were related to variation in series resistance reduced at the beginning due to slightly lowered Fermi level and increased at the end by the serf-compensation by deep in-diffusion of Au nanoparticles.But for our fabricated devices,we know that an oxide layer covered the Si surface,which makes it difficult for the Au ions to diffuse into the Si layer,due to the continuous growth of SiO2 layer on the Si surface which resulted in series resistance decreasing at first and increasing in the end.