A new route for preparation of sodium-silicate-based hydrophobic silica aerogels via ambient-pressure drying

An in-depth investigation into the synthesis of hydrophobic silica aerogels prepared by the surface derivatization of wet gels followed by subsequent drying at ambient pressure is reported. The following sol–gel parameters were examined for their effect on the physical properties of the derived aerogels: number of gel washings with water, percentage of hexane or methanol in silylating mixture, molar ratio of tartaric acid: Na₂SiO₃, gel aging period, weight% of silica, trimethylchlorosilane (TMCS) percentage, and silylation period. These parameters were varied from 1 to 4, 0 to 100%, 0.27 to 1.2, 0 to 4 h, 1.5 to 8 wt.%, 20 to 40% and 6 to 24 h, respectively. The properties of hydrophobic silica aerogels synthesized by this new route were investigated in terms of bulk density, percentage volume shrinkage, percentage porosity, thermal conductivity and contact angle with water, and by Fourier transform infrared spectroscopy (FTIR). The as-prepared hydrophobic silica aerogels exhibited high temperature stability (up to approximately 435 °C) as measured by thermogravimetric/differential thermal analysis (TGA-DTA). The optimal sol-gel parameters were found to be a molar ratio of Na₂SiO₃:H₂O : tartaric acid : TMCS of 1 : 146.67 : 0.86 : 9.46, an aging period of 3 h, four washings with water in 24 h and the use of a 50% hexane- or methanol-based silylating mixture. Aerogels prepared with these optimal parameters were found to exhibit 50% optical transparency in the visible range, 84 kg m⁻³ density, 0.090 W mK⁻¹ thermal conductivity, 95% porosity and a contact angle of 146° with water.     

Assessing methods for blood cell cytotoxic responses to inorganic nanoparticles and nanoparticle aggregates

Inorganic nanoparticles (NPs) show great potential for medicinal therapy. However, biocompatibility studies are essential to determine if they are safe. Here, five different NPs are compared for their cytotoxicity, internalization, aggregation in medium, and reactive oxygen species (ROS) production, using tumoral and normal human blood cells. Differences depending on the cell type are analyzed, and no direct correlation between ROS production and cell toxicity is found. Results are discussed with the aim of standardizing the procedures for the evaluation of the toxicity.     

Synthesis and characterization of photoswitchable fluorescent silica nanoparticles

We have designed and synthesized a new functional (amino reactive) highly efficient fluorescent molecular switch (FMS) with a photochromic diarylethene and a rhodamine fluorescent dye. The reactive group in this FMS -N-hydroxysuccinimide ester- allows selective labeling of amino containing molecules or other materials. In ethanolic solutions, the compound displays a large fluorescent quantum yield of 52 % and a large fluorescence modulation ratio (94 %) between two states that may be interconverted with red and near-UV light. Silica nanoparticles incorporating the new FMS were prepared and characterized, and their spectroscopic and switching properties were also studied. The dye retained its properties after the incorporation into the silica, thereby allowing light-induced reversible high modulation of the fluorescence signal of a single particle for up to 60 cycles, before undergoing irreversible photobleaching. Some applications of these particles in fluorescence microscopy are also demonstrated. In particular, subdiffraction images of nanoparticles were obtained, in the focal plane of a confocal microscope.     

具有纳米孔结构硅质吸附剂的制备及对染料木素的选择性吸附

为了将染料木素从其粗溶液中精确分离出来,制备了一种纳米结构硅质吸附剂．它根据分子识别技术,以染料木素为模板剂,氨丙基三乙氧基硅烷为功能单体,正硅酸乙酯为偶联剂,其中功能单体可以与染料木素的酚羟基发生反应．吸附剂经过BET法、红外分析（FT-IR）和透射电镜（TEM）表征,以及静态吸附实验、选择性实验和洗脱实验．结果表明,此吸附剂有高的比表面积,对染料木素有专一的选择性,能在极性溶剂中识别模板分子;有大量的与模板分子相匹配的纳米孔分布在吸附剂表面,并且有新的化学键形成．由此可以看出,通过模板分子与功能单体强烈的电荷和氢键作用,吸附剂能够专一键合染料木素,而纳米孔则大大提高了吸附能力．     

惯性圆锥破碎机在硅砖生产中的应用试验

惯性圆锥破碎机是一种新型节能细碎设备,对其在硅砖生产中使用的可行性进行了较系统的研究,经过试验和短期生产实践证明,该设备具有破碎比大、过粉碎现象少、产品粒度组成合理、颗粒形状适用且产量高、能耗低特点,对各种硬度的硅石具有很好的适应性,是硅砖生产应当首选的粉碎设备.     

Codelivery of NOD2 and TLR9 Ligands via Nanoengineered Protein Antigen Particles for Improving and Tuning Immune Responses

Vaccine adjuvants that can induce robust protective immunity are highly sought after for the development of safer and more effective vaccines. Vaccine formulation parameters that govern efficacy are still far from clear, such as the diverse impacts of codelivering agonist molecules for innate cell receptors (e.g., pattern recognition receptors). In this study, a mesoporous silica‐templating approach is used to fabricate protein antigen (ovalbumin) particles covalently functionalized with agonists for NOD‐like receptor 2 (NOD2) and Toll‐like receptor 9 (TLR9). Particle‐induced combinatorial NOD2/TLR9 signaling results in synergistic inflammatory cytokine secretion by mouse macrophages (RAW 264.7). Administration of NOD2/TLR9 particles in mice results in adaptive immune responses that are both quantitatively and qualitatively different than those resulting from administration of particles conjugated with either NOD2 or TLR9 agonists alone. While delivery of NOD2 agonists alone activates T helper 2 (Th2)‐type responses (and no CD8+ T cell activation) and delivery of TLR9 agonists alone activates CD8+ T cell and T helper 1 (Th1)‐type responses, codelivery of NOD2 and TLR9 agonists enhances Th1‐type responses and abrogates CD8+ T cell activation. The results illustrate that in the particle‐based system, NOD2 activation plays different roles in polarizing adaptive immune responses depending on coactivation of TLR9.     

Elevating Biomedical Performance of ZnO/SiO2@Amorphous Calcium Phosphate ‐ Bioinspiration Making Possible the Impossible

Here a biomimetic approach is presented to fabricate nanodragon fruits featured by a multitude of tiny quantum dot ZnO seeds embedded in mesosilica (SiO₂) flesh then enclosed in amorphous calcium phosphate (ACP) shell. The nanodragon fruits give rise to a new class of hybrid ZnO/SiO₂@ACP nanocomplex with multimoidal capability: cellular delivering, intracellular targeting, and subcellular imaging. With this particular design, the unusual fluorescent stability of ZnO quantum dots (QDs) in aqueous solution, the specific color selection of the functional ZnO QD seeds, and the stability of transient ACP over a long period of time are made possible. In addition, the nanodragon fruits, capable of targeting mitochondria, have elevated biocompatibility, thus can be of enormous potential applications in treating mitochondrial diseases including inflammation, neurodegeneration, obesity, diabetes, cardiovascular diseases, and cancer. As numerous human disorders are often associated with cellular dysfunctions, this biocompatible carrying platform, capable of delivering, targeting, and imaging subcellular organelles, is therefore highly desirable for efficacious therapeutic and diagnostic treatment.     

A Triple‐Collaborative Strategy for High‐Performance Tumor Therapy by Multifunctional Mesoporous Silica‐Coated Gold Nanorods

To integrate treatments of photothermal therapy, photodynamic therapy (PDT), and chemotherapy, this study reports on a multifunctional nanocomposite based on mesoporous silica‐coated gold nanorod for high‐performance oncotherapy. Gold nanorod core is used as the hyperthermal agent and mesoporous silica shell is used as the reservoir of photosensitizer (Al(III) phthalocyanine chloride tetrasulfonic acid, AlPcS₄). The mesoporous silica shell is modified with β‐cyclodextrin (β‐CD) gatekeeper via redox‐cleavable Pt(IV) complex for controlled drug release. Furthermore, tumor targeting ligand (lactobionic acid, LA) and long‐circulating poly(ethylene glycol) chain are introduced via host–guest interaction. It is found that the nanocomposite can specifically target to hepatoma cells by virtue of the LA targeting moiety. Due to the abundant existence of reducing agents within tumor cells, β‐CD can be removed by reducing the Pt(IV) complex to active cisplatin drug for chemotherapy, along with the releasing of entrapped AlPcS₄ for effective PDT. As confirmed by in vitro and in vivo studies, the nanocomposite exhibits an obvious near‐infrared induced thermal effect, which significantly improves the PDT and chemotherapy efficiency, resulting in a superadditive therapeutic effect. This collaborative strategy paves the way toward high‐performance nanotherapeutics with a superior antitumor efficacy and much reduced side effects.     

Highly Emissive Nd3+‐Sensitized Multilayered Upconversion Nanoparticles for Efficient 795 nm Operated Photodynamic Therapy

Photodynamic therapy (PDT) is a noninvasive and site‐specific therapeutic technique for the clinical treatment of various of superficial diseases. In order to tuning the operation wavelength and improve the tissue penetration of PDT, rare‐earth doped upconversion nanoparticles (UCNPs) with strong anti‐stokes emission are introduced in PDT recently. However, the conventional Yb³⁺‐sensitized UCNPs are excited at 980 nm which is overlapped with the absorption of water, thus resulting in strong overheating effect. Herein, a convenient but effective design to obtain highly emissive 795 nm excited Nd³⁺‐sensitized UCNPs (NaYF₄:Yb,Er@NaYF₄:Yb_0.1Nd_0.4@NaYF₄) is reported, which provides about six times enhanced upconversion luminescence, comparing with traditional UCNPs (NaYF₄:Yb,Er@NaYF₄). A colloidal stable and non‐leaking PDT nanoplatform is fabricated later through a highly PEGylated mesoporous silica layer with covalently linked photosensitizer (Rose Bengal derivative). With as‐prepared Nd³⁺‐sensitized UCNPs, the nanoplatform can produce singlet oxygen more effective than traditional UCNPs. Significant higher penetration depth and lower overheating are demonstrated as well. All these features make as‐prepared nanocomposites excellent platform for PDT treatment. In addition, the nanoplatform with uniform size, high surface area, and excellent colloidal stability can be extended for other biomedical applications, such as imaging probes, biosensors, and drug delivery vehicles.     

氨基膦酸改性硅胶吸附分离铂和钯

采用化学接枝法合成了氨基膦酸改性硅胶吸附剂,考察了其对溶液中铂（Pt）和钯（Pd）的吸附分离性能,测试了溶液pH值、吸附时间、初始金属离子浓度、离子强度和固液比对吸附的影响,并考察了改性硅胶吸附剂的重复使用性能。改性硅胶吸附剂对Pt和Pd的吸附主要受溶液pH值影响,而离子强度和固液比对吸附的影响不大。吸附过程符合准二级吸附动力学模型和Langmuir等温吸附方程。改性硅胶吸附剂180 min时,pH=2时对Pt的平衡吸附容量为18.5 mg/g,pH=6时对Pd的平衡吸附容量为29.9 mg/g,利用改性硅胶吸附剂不同pH值条件下的吸附行为差异可分离回收溶液中的Pt和Pd。用5 mL 0.1 mol/L HNO₃为基质的6%硫脲溶液可实现Pt和Pd的解吸,解吸率分别为99.3%和99.2%。所合成的氨基膦酸硅胶吸附材料可回收重复使用。