Thin Silica Layer Research Articles

Evaluation of <i>In-Vitro</i> Anti-Tuberculosis Activity of <i>Tetrapleura tetraptera</i> Crude and Fractions on Multidrug Resistant <i>Mycobacterium tuberculosis</i>

The management, control and elimination of tuberculosis (TB) have been difficult with the advent of HIV and cases of multidrug resistant (MDR-TB) tuberculosis. The cases of multidrug resistance to rifampicin and isoniazid pose greater challenges on first line and second line drugs to eliminate TB. The study is aimed at establishing anti-tuberculosis activity of Tetrapleura tetraptera against Mycobacterium tuberculosis and MDR-TB and the phytochemical present. The leaves of Tetrapleura tetraptera were collected, weighed, dried and pulverized to powder. The pulverized leaves of Tetrapleura tetraptera were subjected to 70% methanol extraction and screened for phytochemical. The crude extract was further purified into fractions using silica gel and thin layer chromatography techniques. M. tuberculosis and MDR-TB were obtained from positive acid fast bacilli sputa of TB patients and confirmed using GeneXpert to differentiate genotypic drug susceptible M. tuberculosis and MDR-TB. The sputa were digested using sodium hydroxide-cysteine technique and cultured in Middlebrook 7H9. The crude extract and fractions were screened for anti-tuberculosis activity using tetrazolium microtitre plate assay. The results showed that Tetrapleura tetraptera crude had activities against M. tuberculosis at 7.4 ± 0 mg/ml and 27.5 ± 0 mg/ml for MDR-TB. One of the fractions inhibited the growth of M. tuberculosis at 0.24 ± 0 mg/ml and MDR-TB at 0.89 ± 0 mg/ml. The phytochemical screened includes tannins, alkaloids, saponins, flavonoids, phenols and resins. T. tetraptra possesses anti-tuberculosis potential at low concentration on MDR-TB and can be a lead compound in drug development for the treatment of tuberculosis and multidrug resistant tuberculosis.

Magnetic Nanomotor-Based Maneuverable SERS Probe.

Surface-enhanced Raman spectroscopy (SERS) is a powerful sensing technique capable of capturing ultrasensitive fingerprint signal of analytes with extremely low concentration. However, conventional SERS probes are passive nanoparticles which are usually massively applied for biochemical sensing, lacking controllability and adaptability for precise and targeted sensing at a small scale. Herein, we report a “rod-like” magnetic nanomotor-based SERS probe (MNM-SP) that integrates a mobile and controllable platform of micro-/nanomotors with a SERS sensing technique. The “rod-like” structure is prepared by coating a thin layer of silica onto the self-assembled magnetic nanoparticles. Afterwards, SERS hotspots of silver nanoparticles (AgNPs) are decorated as detecting nanoprobes. The MNM-SPs can be navigated on-demand to avoid obstacles and target sensing sites by the guidance of an external gradient magnetic field. Through applying a rotating magnetic field, the MNM-SPs can actively rotate to efficiently stir and mix surrounding fluid and thus contact with analytes quickly for SERS sensing. Innovatively, we demonstrate the self-cleaning capability of the MNM-SPs which can be used to overcome the contamination problem of traditional single-use SERS probes. Furthermore, the MNM-SPs could precisely approach the targeted single cell and then enter into the cell by endocytosis. It is worth mentioning that by the effective mixing of intracellular biocomponents, much more informative Raman signals with improved signal-to-noise ratio can be captured after active rotation. Therefore, the demonstrated magnetically activated MNM-SPs that are endowed with SERS sensing capability pave way to the future development of smart sensing probes with maneuverability for biochemical analysis at the micro-/nanoscale.

Effects of Sphingolipid Fractions from Golden Oyster Mushroom (Pleurotus citrinopileatus) on Apoptosis Induced by Inflammatory Stress in an Intestinal Tract in vitro Model.

Previously, we reported that the polar lipid fraction from the golden oyster mushroom, Pleurotus citrinopileatus, suppresses colon injuries which result from apoptosis induced by inflammatory stresses in vivo and in vitro (Yamashita et al., J. Oleo Sci., 69, 751-757 (2020)). Here, we investigated the use of lipid classes in mushroom polar lipid fraction in alleviating colon injury using differentiated Caco-2 cells as an intestinal tract model. The mushroom polar lipid fraction was separated into four fractions using silica thin layer chromatography. Each mushroom polar lipid fraction suppressed lipopolysaccharide (LPS)-induced decreases in the viability of intestinal cells, and the effects of sphingolipid fractions were significantly stronger than those of fraction that did not contain sphingolipids. Addition of sphingolipid fractions suppressed the expression of apoptosis-related proteins (e.g., death receptors and caspases) in the LPS-treated cells. Mushroom polar lipids, especially sphingolipids suppress intestinal apoptosis induced by inflammatory stress, and highly polar sphingolipids may exert stronger suppressive effects.

Identifikasi Senyawa Metabolit Sekunder Ekstrak Etanol Kulit Buah Pisang Kepok (Musa paradisiaca L) dengan Metode KLT

Indonesia is a country that is rich in abundant natural plants by having various types of plants which have medicinal properties and are used by some people as traditional medicines. One use of traditional medicine used by the community is the banana plant. So far the community only uses bananas, limited to the use of their fruit, then the banana peel after consumption is only disposed of as waste that is not used optimally by the community. This study aims to identify the chemical compounds found in the skin of Kepok Banana (Musa paradisiaca L) taken from the pioneer road in the city of Makassar. This identification is carried out using the Thin Layer Chromatography (TLC) method and chemical reagents. Kepok banana peel extract (Musa paradisiaca L.) is made using maceration method, because the method is not only simple, the equipment used is simple, easy to work on, can also avoid damage to compound components due to heat. The yield of Rendamen obtained was 12.06%. Identification was done using Silica Thin Layer Chromatography GF254 with N-hexane eluent: ethyl acetate (6: 4) eluents obtained 5 stains on 366 nm UV light, namely alkaloids with orange blotches with Rf value (0.13), saponins with blemishes. purple Rf value (0.92), flavonoids with yellow spots Rf values ​​(0.33) and tannins with blackish orange patches Rf values ​​(0.65). Based on testing using chemical reagents obtained positive results saponins, flavonoids, tannins and alkaloids. The conclusion of the study showed that the Kepok banana peel extract taken on the pioneering road of Makassar city contained alkaloids, saponins, flavonoids and tannins.

Magnetic molecularly imprinted multishell particles for zearalenone recognition

This paper deal with the synthesis and characterization of a new class of magnetic molecularly imprinted (MIP) particles, with selective recognition properties for Zearalenone (ZEN), an estrogenic mycotoxin. These particles present a multishell structure, comprising a magnetic core, constituted by spherical aggregates of magnetite nanoparticles (Fe3O4 nanoparticles), covered by a thin silica layer and surrounded by a molecularly imprinted (MIP) polymer shell, obtained employing quercetin as the dummy template and 4-vinylpyridine as the functional monomer. A multistep synthetic procedure was developed leading to spherical particles with a mean diameter of approximately 900 nm and a high magnetic fraction. The MIP were tested for ZEN re-binding properties. ZEN-MIP material had 55-fold more affinity for ZEN than the corresponding non-imprinted (NIP) material, that highlighting their potential for ZEN concentration from complex food matrices.

Doxorubicin/Cisplatin-Loaded Superparamagnetic Nanoparticles As A Stimuli-Responsive Co-Delivery System For Chemo-Photothermal Therapy.

IntroductionTo date, numerous iron-based nanostructures have been designed for cancer therapy applications. Although some of them were promising for clinical applications, few efforts have been made to maximize the therapeutic index of these carriers. Herein, PEGylated silica-coated iron oxide nanoparticles (PS-IONs) were introduced as multipurpose stimuli-responsive co-delivery nanocarriers for a combination of dual-drug chemotherapy and photothermal therapy.MethodsSuperparamagnetic iron oxide nanoparticles were synthesized via the sonochemical method and coated by a thin layer of silica. The nanostructures were then further modified with a layer of di-carboxylate polyethylene glycol (6 kDa) and carboxylate-methoxy polyethylene glycol (6 kDa) to improve their stability, biocompatibility, and drug loading capability. Doxorubicin (DOX) and cisplatin (CDDP) were loaded on the PS-IONs through the interactions between the drug molecules and polyethylene glycol.ResultsThe PS-IONs demonstrated excellent cellular uptake, cytocompatibility, and hemocompatibility at the practical dosage. Furthermore, in addition to being an appropriate MRI agent, PS-IONs demonstrated superb photothermal property in 0.5 W/cm2 of 808 nm laser irradiation. The release of both drugs was effectively triggered by pH and NIR irradiation. As a result of the intracellular combination chemotherapy and 10 min of safe power laser irradiation, the highest cytotoxicity for iron-based nanocarriers (97.3±0.8%) was achieved.ConclusionThe results of this study indicate the great potential of PS-IONs as a multifunctional targeted co-delivery system for cancer theranostic application and the advantage of employing proper combination therapy for cancer eradication.

Comparison of experimental and simulation results on catalytic HI decomposition in a silica-based ceramic membrane reactor

In this study, the catalytic decomposition of hydrogen iodide was theoretically and experimentally investigated in a silica-based ceramic membrane reactor to assess the reactor's suitability for thermochemical hydrogen production. The silica membranes were fabricated by depositing a thin silica layer onto the surface of porous alumina ceramic support tubes via counter-diffusion chemical vapor deposition of hexyltrimethoxysilane. The performance of the silica-based ceramic membrane reactor was evaluated by exploring important operating parameters such as the flow rates of the hydrogen iodide feed and the nitrogen sweep gas. The influence of the flow rates on the hydrogen iodide decomposition conversion was investigated in the lower range of the investigated feed flow rates and in the higher range of the sweep-gas flow rates. The experimental data agreed with the simulation results reasonably well, and both highlighted the possibility of achieving a conversion greater than 0.70 at decomposition temperature of 400 °C. Therefore, the developed silica-based ceramic membrane reactor could enhance the total thermal efficiency of the thermochemical process.

Sandwich-Structured Upconversion Nanoprobes Coated with a Thin Silica Layer for Mitochondria-Targeted Cooperative Photodynamic Therapy for Solid Malignant Tumors

Upconversion nanoparticles-based photodynamic nanotheranostic agents (UCNPs-PDT) have received great interest due to improved tissue penetration, weak autofluorescence, and low biotoxicity. However, conventional UCNPs-PDT are often limited by low energy transfer efficiency from UCNPs to photosensitizer (PS) molecules and insufficient generation and limited diffusion distance of reactive oxygen species (ROSs). Herein, an "all in one" nanotheranostic agent has been developed which has multicolor sandwich-structured UCNPs (SWUCNPs) as the core, a thin silica layer with a mitochondria-targeted group for loading dual PS as the medium layer, and polyethylene glycol-folic acid (PEG-FA) chains as the outer layer. Multicolor SWUCNPs simultaneously achieve two-photon fluorescence imaging and serve as energy donor for dual PS molecules. The thin luminescence layer and silica layer control most UCNPs activators and PS molecules in the effective energy transfer distance to guarantee a high energy transfer efficiency. Via FA-mediated endocytosis, the nanotheranostic agent is selectively endocytosed by cancer cells, is released from the endosome/lysosome, targets the mitochondria, and in situ produces ROSs under excitation from NIR, leading to significant mitochondria-mediated cell apoptosis. Furthermore, the established nanotheranostic agent shows tumor targetability, increased generation of ROSs, high PDT efficacy, significant cell apoptosis, minimal systemic cytotoxicity, and efficacious in vivo tumor inhibition.

Bioactive superparamagnetic nanoparticles for multifunctional composite bone cements

Abstract Magnetite-based nanoparticles (NPs) were synthesized by co-precipitation process and coated with a thin layer of silica, eventually doped with calcium, by a modified Stober method. The potential bioactive behavior of NPs was investigated by dipping samples in simulated body fluid (SBF) and analyzing them with Field-Emission Scanning Electron Microscope (FESEM) equipped with Energy Dispersive Spectroscopy (EDS). Silica-coated NPs displayed evidence of HAp grown on their surface and were then used as a filler for polymethyl methacrylate (PMMA)-based bone cement to impart bioactive and magnetic properties. The influence of the amount of magnetic NPs and the cement mixing method (manual or mechanical) were estimated in terms of NPs dispersion, compressive strength and bioactive behavior. The obtained data evidenced that both the NPs amount and the mixing method influenced the strength of the composites. A delay in the bioactivity was observed for manual mixed cement; moreover, mechanically mixed composites containing a low amount of NPs showed superparamagnetic behavior. These results suggest that the investigated composite bone cements are promising materials for the treatment of bone tumors and associated complications.

Homogeneous melanin/silica core-shell particles incorporated in poly (methyl methacrylate) for enhanced UV protection, thermal stability, and mechanical properties

Natural melanin is abundant in wide ranges of sources, especially in dark colored animal fibers. Despite the unique features and functionalities, its extensive analyses and applications have greatly been hindered due to its serious self-aggregation. To tackle this issue, this study uses the Stöber method to encapsulate the melanin particles extracted from colored alpaca fibers with a thin layer of silica. It was observed that the melanin/silica core-shell particles (MSCPs) with 20 h encapsulation time provided excellent dispersity and optical performance. Different concentrations of MSCPs were then doped in poly (methyl methacrylate) (PMMA) through an in-situ polymerization process to obtain MSCP/PMMA bulk materials. The produced composite materials showed homogeneous appearance, controllable UV absorbance and visible light transmittance. The thermal stability, durability under UV, and mechanical properties of the fabricated composites were examined and the role of melanin on the obtained results was elucidated. It was observed that the PMMA samples with MSCPs showed excellent durability under UV even after 100 h irradiation. Testing the thermal stability and mechanical properties (hardness and elastic modulus) of MSCP/PMMA samples confirmed the positive effect of MSCPs presence in PMMA. These results demonstrated the applicability of natural melanin-based materials and composites in UV-protection related fields.

Synthesis and characterization of hydrophobic silica prepared by different acid catalysts

Silica particles tend to be aggregate and difficult to be dispersed homogeneously in organic coatings or polymer nanocomposites because of the large number of -OH groups in the surface, and this remains an obstacle to further applications. Surface modification was carried out to improve silica hydrophobic ability in order to afford materials with anticipated functional properties. Improving hydrophobic ability can be achieved by using silylation agent Dimethoxydimethylsilane (DMDMS). Synthesis of hydrophobic silica TEOS-DMDMS was conducted by sol-gel process. TEOS-DMDMS was dissolved into ethanol solution with molar ratio of TEOS:DMDMS:EtOH 1:0.5:50 by using magnetic stirrer. Various acid catalysts (CH3COOH, H2C2O4, HNO3, and H2SO4) were added to the ethanol solvent until they reached the same pHs of 3.5. The TEOS-DMDMS sols were used for the surface modification of the glass slide by dip-coating method and then were calcined at temperatures of 300°C, 500°C and 600°C. The hydrophobicity of thin silica thin layers was tested by measuring water contact angle (WCA) and silica xerogels were investigated by TGA and FTIR to determine the thermal properties and characteristics of each functional groups. The WCA values of the uncalcined silica, calcined at 300°C and calcined at 500°C were in the range of 85.4-89.6°, 90.5-92.6°, and 50.4-59.7° respectively. The results of the TGA analysis showed that the TEOS-DMDMS silica began to lose its hydrophobicity starting from temperature of 325°C. The FTIR spectra showed no significant difference in functional groups of the sample prepared from all acid catalysts.

A new alternative method for quantitative analysis by thin layer chromatography using a lab-made multi-track device and image-based chromatograms

This work describes a simple, low-cost, and innovative approach to perform quantitative analyses by thin layer chromatography (TLC) combined with image-based detection with UV revelation, which enables the acquisition of chromatograms. Lab-made aluminium TLC devices containing eight individual tracks with thin fluorescent silica layers were developed, evaluated, and used to perform the separation and quantification of acetaminophen (ACM), caffeine (CAF), and acetylsalicylic acid (ASA) in medicine tablets by using image-based detection performed with a webcam and software written in VisualStudio. The proposed device enables vertical development of the separation with proper reproducibility of retention factors (<2%) and of the peak heights (<8%), without occurrence of silica damage, demonstrating the applicability of the new approach. By using a mixture of ethyl acetate/acetic acid (80:2 v/v) as eluent, analytical curves were obtained for the analytes based on the chromatographic peak heights, providing linear relationships (R > 0.996) for the studied concentration ranges ACM (0.18–0.54 mg mL−1), CAF (0.50–3.00 mg mL−1) and ASA (0.70–4.50 mg mL−1) with estimated limits of detection (LOD) of 0.14 mg mL−1, 0.40 mg mL−1 and 0.56 mg mL−1, for ACM, CAF and ASA, respectively. In addition, no significant differences (95% confidence level) were observed by comparing the average concentration of the analytes determined by the proposed method and those obtained by a reference HPLC based method, indicating an adequate accuracy of the procedures.

Tuning Localized Surface Plasmon Resonance of Nanoporous Gold with a Silica Shell for Surface Enhanced Raman Scattering.

We report the tuning of localized surface plasmon resonance (LSPR) of nanoporous gold (NPG) by silica coating, which also affects the surface enhanced Raman scattering (SERS) of NPG. In this study, controllable silica shell is assembled on the NPG surface, and a fully silica thin layer causes more than 50 nm red-shift of LSPR band due to dielectric medium dependence. Additionally, ~1 nm silica coated NPG film shows excellent SERS enhancement, which is due to electromagnetic coupling between ligaments and local surface plasmon field enhancement within pores, and theoretical analysis indicates that silica coating further improves the coupling effect, which demonstrates the electromagnetic origin of the tuning of SERS effect.

Information Content in Nuclear Medicine Imaging

The aim of the present study was to investigate the information content of positron emission tomography (PET) images. We used the GATE Monte Carlo package (GEANT4 application for tomographic emission) and reconstructed images, obtained using the software for tomographic image reconstruction (STIR). The case study for the investigation of the PET images information content was the General Electric Discovery-ST (USA) PET scanner. A thin film plane source aluminum (Al) foil, coated with a thin layer of silica and a fluorodeoxyglucose (18F-FDG) bath distribution of (1 MBq) was used in the simulation for the image signal to noise ratio assessment. The influence of the maximum likelihood estimation ordered subsets maximum a posteriori one step late (MLE)-OS-MAP-OSL algorithm, using various subsets (1 to 21) and iterations (1 to 20) was examined. The image information content was assessed in terms of the information capacity (IC). Results showed that the single index information capacity maximized for the range of 8-20 iterations and 3 subsets. In conclusion, our study showed that the image information content of PET scanners can be fully characterized and further improved by investigation of the imaging chain components through Monte Carlo methods. Moreover, new perspectives are created by using the suggested techniques in the context of a global cloud service that could serve as an online quality evaluation metric for the PET scanners and other medical imaging systems.

Controllable fabrication of magnetic core-shell nanocomposites with high peroxide mimetic properties for bacterial detection and antibacterial applications.

Pathogenic bacterial infection has become a growing threat to public health; therefore, exploration of a sensitive and specific method for the identification of bacteria is very important. In this report, we fabricated a new magnetic core-shell nanocomposite with a homogenous morphology. The Fe3O4 nanoparticle core with a diameter of 15 nm was coated with a thin silica layer, and the thickness of the layer was finely adjusted to about 10 nm. Pt nanoclusters with a diameter of 2-3 nm were anchored uniformly on the surface to form Fe3O4@SiO2-Pt nanocomposites. These nanocomposites exhibited excellent peroxide enzyme activity and acted as a signal-output probe for the identification of pathogenic bacteria. This strategy was also based on using vancomycin (Van) as the capture agent in an ELISA procedure. The detection limit for S. aureus was around 1 × 101 cfu mL-1. Furthermore, Fe3O4@Si-Pt nanocomposites also show ideal bacteria separation and inhibition effects, and can act as a multifunctional platform for bacterial detection and antibacterial applications.

Mesoporous Silica-gold Films for Straightforward, Highly Reproducible Monitoring of Mercury Traces in Water.

Trace-level detection of mercury in waters is connected with several complications including complex multistep analysis routines, applying additional, harmful reagents increasing the risk of contamination, and the need for expensive analysis equipment. Here, we present a straightforward reagent-free approach for mercury trace determination using a novel thin film sampling stick for passive sampling based on gold nanoparticles. The nanoparticles supported on a silicon wafer and further covered with a thin layer of mesoporous silica. The mesoporous silica layer is acting as a protection layer preventing gold desorption upon exposure to water. The gold nanoparticles are created by thermal treatment of a homogenous gold layer on silicon wafer prepared by vacuum evaporation. This gold-covered substrate is subsequently covered by a layer of mesoporous silica through dip-coating. Dissolved mercury ions are extracted from a water sample, e.g., river water, by incorporation into the gold matrix in a diffusion-controlled manner. Thus, the amount of mercury accumulated during sampling depends on the mercury concentration of the water sample, the accumulation time, as well as the size of the substrate. Therefore, the experimental conditions can be chosen to fit any given mercury concentration level without loss of sensitivity. Determination of the mercury amount collected on the stick is performed after thermal desorption of mercury in the gas phase using atomic fluorescence spectrometry. Furthermore, the substrates can be re-used several tens of times without any loss of performance, and the batch-to-batch variations are minimal. Therefore, the nanogold-mesoporous silica sampling substrates allow for highly sensitive, simple, and reagent-free determination of mercury trace concentrations in waters, which should also be applicable for on-site analysis. Successful validation of the method was shown by measurement of mercury concentration in the certified reference material ORMS-5, a river water.

Shaping Silica Rods by Tuning Hydrolysis and Condensation of Silica Precursors.

We present the synthesis of colloidal silica particles with new shapes by manipulating the growth conditions of rods that are growing from polyvinylpyrrolidone-loaded water-rich droplets containing ammonia and ethanol. The silica rods grow by ammonia-catalyzed hydrolysis and condensation of tetraethoxysilane (TEOS). The lengthwise growth of these silica rods gives us the opportunity to change the conditions at any time during the reaction. In this work, we vary the availability of hydrolyzed monomers as a function of time and study how the change in balance between the hydrolysis and condensation reactions affects a typical synthesis (as described in more detail by our group earlier1). First, we show that in a “standard” synthesis, there are two silica growth processes occurring; one in the oil phase and one in the droplet. The growth process in the water droplet causes the lengthwise growth of the rods. The growth process in the oil phase produces a thin silica layer around the rods, but also causes the nucleation of 70 nm silica spheres. During a typical rod growth, silica formation mainly takes place in the droplet. The addition of partially hydrolyzed TEOS or tetramethoxysilane (TMOS) to the growth mixture results in a change in balance between the hydrolysis and condensation reaction. As a result, the growth also starts to take place on the surface of the water droplet and thus from the oil phase, not only from inside the droplet onto a silica rod sticking out of the droplet. Carefully tuning the growth from the droplet and the growth from the oil phase allowed us to create nanospheres, hollow silica rods, hollow sphere rod systems (colloidal matchsticks), and bent silica rods.

Information Capacity of Positron Emission Tomography Scanners

Background: The aim of the present study was to assess the upper information content bound of positron emission tomography (PET) images, by means of the information capacity (IC). Methods: The Geant4 Application for the Tomographic Emission (GATE) Monte Carlo (MC) package was used, and reconstructed images were obtained by using the software for tomographic image reconstruction (STIR). The case study for the assessment of the information content was the General Electric (GE) Discovery-ST PET scanner. A thin-film plane source aluminum (Al) foil, coated with a thin layer of silica and with a 18F-fludeoxyglucose (FDG) bath distribution of 1 MBq was used. The influence of the (a) maximum likelihood estimation-ordered subsets-maximum a posteriori probability-one step late (MLE-OS-MAP-OSL) algorithm, using various subsets (1 to 21) and iterations (1 to 20) and (b) different scintillating crystals on PET scanner’s performance, was examined. The study was focused on the noise equivalent quanta (NEQ) and on the single index IC. Images of configurations by using different crystals were obtained after the commonly used 2-dimensional filtered back projection (FBP2D), 3-dimensional filtered back projection re-projection (FPB3DRP) and the (MLE)-OS-MAP-OSL algorithms. Results: Results shown that the images obtained with one subset and various iterations provided maximum NEQ values, however with a steep drop-off after 0.045 cycles/mm. The single index IC data were maximized for the range of 8–20 iterations and three subsets. The PET scanner configuration incorporating lutetium orthoaluminate perovskite (LuAP) crystals provided the highest NEQ values in 2D FBP for spatial frequencies higher than 0.028 cycles/mm. Bismuth germanium oxide (BGO) shows clear dominance against all other examined crystals across the spatial frequency range, in both 3D FBP and OS-MAP-OSL. The particular PET scanner provided optimum IC values using FBP3DRP and BGO crystals (2.4829 bits/mm2). Conclusions: The upper bound of the image information content of PET scanners can be fully characterized and further improved by investigating the imaging chain components through MC methods.

Synthesis, Characterization, and Applications of Polymer-Silica Core-Shell Microparticle Capsules.

Encapsulation is a powerful method for the targeted delivery of concentrated reagents and capture of valuable materials in dilute systems. To this end, many encapsulation schemes for specific scenarios have been devised that incorporate chemospecificity or stimulus response in terms of uptake or release. However, an encapsulation platform that enables highly tailorable surface chemistry for targeting, stimulus response, and core chemistry for capture and release of reagents remains elusive. Here, we present such a system comprising composite core-shell capsule particles of hydrophilic polymers coated with thin silica layers synthesized via straightforward one-pot syntheses. Silica is found to encapsulate a range of polymer hydrogels through a mechanism independent of the specific core chemistry. The hybrid materials possess significantly enhanced rigidity while allowing surface modification through simple yet versatile silane coupling reactions without a reduction in the functionality of the core. They are shown to have applications as diverse as recyclable catalysis and controlled delivery vehicles for agrochemicals. The successful synthesis and utilization of this catalog of materials indicate the broader capability of simple composite structures in an array of high-value applications.

Robust, reproducible, recyclable SERS substrates: monolayers of gold nanostars grafted on glass and coated with a thin silica layer

We prepared and characterized recyclable surface enhanced Raman spectroscopy (SERS) active glass chips. Gold nanostars were grafted on properly functionalized glasses by means of electrostatic interactions and then they were coated with a silica layer of controllable thickness in the nanometer range. The SERS activity of the obtained substrates were tested in terms of reproducibility and homogeneity intra-samples and inter-samples from different batches using the Raman reporter as the model compound rhodamine 6G. The uncoated substrates were used as reference to evaluate the effect of silica spacers on SERS enhancement factors (EFs). The chemical route to obtain silica-coated SERS chips is described in detail, and the morphology and the optical response of substrates have been characterized. We demonstrate that SERS substrates coated with 1 nm silica conserve a good EF, and that the coating confers to the SERS platform an extreme robustness leading to reusability of the substrates.