Currently, there is an increased interest in aluminosilicates of natural origin, both in connection with the use in detoxification of waters and soils, and as a matrix for the creation of biologically active composites. The morphological characteristics of glauconite grains from the Beloozersk deposit in the Saratov region and its composite have been studied by scanning electron microscopy. The main sorption characteristics of the enriched fraction of glauconite in relation to chlorhexidine digluconate were determined by spectrophotometry. On the basis of the presented sorption isotherm, the mechanism of immobilization of chlorhexidine ions on a glauconite matrix is analyzed in accordance with the provisions of Langmuir's theory. The basic constants of the Langmuir equation are determined. It was revealed that glauconite has a high sorption activity (up to 87%) in relation to chlorhexidine, which can be in demand as filter media in wastewater treatment, in agriculture, as well as in medicine and veterinary medicine, to create new types of enterosorbents with antibacterial properties.
Medications with an antiseptic effect for the treatment of pain in the mouth and throat are especially relevant in the autumn-winter period. The composition of these drugs, in addition to the active substances with antiseptic action, also include auxiliary substances, for example, synthetic food colorants (SFC). The need to control the amount of SFC consumed is an important task, since exceeding the permissible daily intake can lead to allergic reactions, hyperactivity in children. Two chemometric methods applied were partial least squares (PLS) and principal component regression (PCR). These approaches were used to quantify the colorants in model colorants solutions and "Strepsils" lozenges aqueous solution based on information included in the visual absorption spectra. The calibration PLS and PCR models were evaluated by internal validation (prediction of compounds in its own designed training set of calibration) and by external validation over pharmaceutical preparation. The accuracy of the methods was evaluated through the root mean square error of prediction (RMSEP). The results of PLS and PCR methods were compared and the best models for the system were obtained with PCR. Ultimately, a method was developed for the chemometric-assisted spectrophotometric determination of E110 in the presence of E124 in the "Strepsils" tablets, which is characterized by simplicity and rapidity.
The dosing uniformity indicator of the «Papazol» tablets of two manufacturers was evaluated according to the Russian State Pharmacopoeia XIV and by Principal Component Analyis (РСА). The pharmacopoeial method showed that “Papazol” tablets (“Pharmstandart-Leksredstva”) satisfy the requirements for dosage uniformity. “Papazol” tablets (“Irbit Chemical Pharmaceutical Plant”) do not meet the requirements for dosing uniformity. The possibility of the PCA method application for rapid testing of “Papazol” tablets for dosage uniformity was investigated. The results obtained are consistent with the data obtained using the pharmacopoeial direct determination method. The objective of this study was to present the spectrophotometry method coupled with chemometrics approaches as a simple, cost-effective, and accurate for the dosing uniformity indicator testing in pharmaceutical formulation.
Recently, there has been great interest in the potential use of metal nanoparticles in various fields: physics, medicine, microelectronics, biology, etc. Copper nanoparticles are not inferior in properties to nanoparticles of noble metals, however, they are much cheaper and more accessible. This work shows the preparation of an effective bactericidal composite with copper nanoparticles. Glauconite from the Beloozersk deposit in the Saratov region was used as a matrix for creating the composite. Glauconite can be a stabilizer for air-unstable copper nanoparticles. The glauconite structure has nanoscale porosity, which largely increases the effective sorption surface. The copper nanoparticles obtained by the chemical reduction were immobilized on a glauconite matrix. Sorption of nanoparticles was monitored by spectrophotometry. The bactericidal efficacy of the obtained nanocomposite was investigated in relation to clinical bacterial strains. These studies can be in demand in veterinary medicine, agriculture and medicine, after additional research.
Encapsulation of various nanoparticles in nanofibers has become one of the most interesting topics in the field of electrospinning and SERS. Literature review shows that several main approaches can be distinguished for the preparation of electrospun nanofibers with embedded metal nanostructures. However, there is no information about the comparison of various methods of metal nanoparticles introduction into nanofiber-based SERS-platforms. Three main approaches were used here for preparation of SERS-platforms based on electrospun nanofibers with embedded silver nanoparticles: synthesis of metal nanostructures inside fibers prepared with incorporated precursor, metal nanostructures synthesis via their nucleation in prepared nanofibers and sorption of metal nanostructures onto ready-made nanofibers. SERS-platforms based on polyacrylonitrile nanofibers containing various concentrations of Ag nanoparticles were obtained using techniques described above and tested.
Photonic crystal fibers (PCFs) are one of the most promising materials for biosensors construction due to their unique optical properties. The modification of PCF by noble metal nanoparticles (NPs) provides the SPR and SERS signal detection where as the application amino group-containing compounds allows efficient binding of biomolecules. In this work the internal surface of glass hollow core photonic crystal fibers (HC-PCFs) has been modified Ag and Au nanoparticles using three different approaches. PCFs were treated by: 1) mixture of NPs and precursors for silanization (tetraethoxysilane (TEOS) and (3-aminopropyl)triethoxysilane (APTES)); 2) alternately deposition of polyelectrolytes and NPs, 3) mixture of chitosan with NPs. The shift of local maxima in the HC-PCF transmission spectrum has been selected as a signal for estimating the amount of NPs on the HC-PCF inner surface. The most efficient techniques were the chitosan application for Ag NPs and silanization for Au NPs. The obtaining PCFs could be useful for creating biosensitive elements.
New SERS-active materials were obtained by preparation of alumina with embedded silver nanoparticles and their application both as sorbents for pre-concentration and SERS platforms was studied. The influence of ionic strength on Ag NPs size, absorption spectra and SERS signal was investigated. Synthesized materials were examined by Raman spectroscopy, scanning electron microscopy, and UV-visible spectroscopy. The optimal conditions for SERSmeasurements were chosen. Synthesized materials were applied for pre-concentration of model analytes (Rhodamine 6G, folic acid and pyrene) and their SERS detection directly within the sorbent. It was shown that the recovery of analytes could be improved by alumina modification. The combination of surface-enhanced Raman spectroscopy with preconcentration is a promising instrument for analytical applications.
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