Molecular Plasmonic Silver Forests for the Photocatalytic-Driven Sensing Platforms

Structural electronics, as well as flexible and wearable devices are applications that are possible by merging polymers with metal nanoparticles. However, using conventional technologies, it is challenging to fabricate plasmonic structures that remain flexible. We developed three-dimensional (3D) plasmonic nanostructures/polymer sensors via single-step laser processing and further functionalization with 4-nitrobenzenethiol (4-NBT) as a molecular probe. These sensors allow ultrasensitive detection with surface-enhanced Raman spectroscopy (SERS). We tracked the 4-NBT plasmonic enhancement and changes in its vibrational spectrum under the chemical environment perturbations. As a model system, we investigated the sensor’s performance when exposed to prostate cancer cells’ media over 7 days showing the possibility of identifying the cell death reflected in the environment through the effects on the 4-NBT probe. Thus, the fabricated sensor could have an impact on the monitoring of the cancer treatment process. Moreover, the laser-driven nanoparticles/polymer intermixing resulted in a free-form electrically conductive composite that withstands over 1000 bending cycles without losing electrical properties. Our results bridge the gap between plasmonic sensing with SERS and flexible electronics in a scalable, energy-efficient, inexpensive, and environmentally friendly way.</p

Highly Sensitive Immunochromatographic Identification of Tetracycline Antibiotics in Milk

A rapid immunochromatographic assay was developed for the control of tetracycline (TC). The assay is based on the competition between immobilized TC-protein conjugate and TC in a tested sample for binding with polyclonal anti-TC antibodies conjugated to colloidal gold during the flow of the sample along a membrane strip with immobilized reactants. Conjugation of colloidal gold and the total immunoglobulin (IgG) fraction of polyclonal antibodies was used to increase the assay sensitivity to ensure low content of specific antibodies in the conjugate. This allowed effective inhibition of free TC and conjugate binding in the strip test zone. Photometric marker registration allows control of the reduction of binding, thereby enhancing detection sensitivity. The proposed assay allows TC to be detected at concentrations up to 20 ng/mL, exceeding the limit of detection of the known analogues, in a wide working range (more than two orders) of 60 pg/mL to 10 ng/mL, ensured through the use of polyclonal antibodies. The assay time is 10 min. The efficiency of the designed assay is shown to identify TC in milk; the degree of recovery of TC ranges from 90 to 112%. The precision of the concentrations measurements was no more than 10%

Liquid Sensor Based on a Piezoelectric Resonator with a Lateral Electric Field Made of Piezo-Ceramics PZT

Поступила: 30.09.2019. Принята в печать: 10.10.2019.Статья является расширенной версией доклада, представленного на 29-й Международной Крымской конференции «СВЧ-техника и телекоммуникационные технологии» — КрыМиКо’2019 (Севастополь, РФ, 8–14 сентября 2019 г.).Received: 30.09.2019. Accepted: 10.10.2019.Экспериментально и теоретически исследовано влияние проводимости жидкости, контактирующей с пьезоэлектрическим резонатором с поперечным электрическим полем на основе пластины пьезокерамики ЦТС-19. В данном резонаторе поперечная компонента механического смещения, не приводящая к радиационным потерям при контакте с жидкостью, является превалирующей. Частотные зависимости реальной и мнимой частей электрического импеданса резонатора показали наличие трех резонансов на частотах 68,7, 97,8 и 264 кГц со значениями коэффициента электромеханической связи 12,2, 14,7 и 6,5 % соответственно. Добротность каждого резонанса при контакте с жидкостью оказалась существенно выше добротности резонатора c продольной акустической волной на основе ниобата лития. Были получены зависимости максимального значения действительной части электрического импеданса такого резонатора от проводимости жидкости. Проведен теоретический анализ влияния проводимости жидкости на характеристики резонатора.This paper demonstrates the results of the study of the sensor based on the resonator with the lateral electric field made of the ceramic PZT for measuring the conductivity of the contacting liquid. This sensor is made of the PZT ceramic plate of 3.54 mm thickness with shear dimension of 20×18 mm2.Two electrodes with the gap width of 4 mm are deposited on one side of the plate. The sensor features the 4 ml plexiglass container, the bottom of which is a resonator. The measured frequency dependences of the real and imaginary parts of the electrical impedance shows three resonances at frequencies of 68.7, 97.8, and 264 kHz. Aqueous solutions of sodium chloride are prepared with different conductivities in the range 3.2 – 9000 μS/cm. We have measured the frequency dependences of the real and imaginary parts of the sensor electric impedance with the liquid of different conductivity. The maximum value of the real part of the electric impedance monotonically decreases and reaches saturation for each resonance peak with increasing liquid conductivity. Theoretical analysis of influence of liquid conductivity on resonator impedance was also performed using equivalent circuit with two parallel branches. First branch included active and reactive resistors that corresponded to excitation of acoustic wave. The second branch includes the static capacitance of the resonator. We describe the presence of the conductive liquid by means of the leakage resistance connected with the capacitance in parallel. We underline that theoretical and experimental dependences are in a good agreement. Therefore the resonator with the lateral electric field based on the ceramic PZT shows high sensitivity to the changes in the conductivity of the liquid due to the high value of the coefficient of the electromechanical coupling. The sensor with liquid presence compared to the sensor made of lithium niobate with a longitudinal acoustic wave has a higher quality factor. We conclude that in the resonator made of piezoceramics, the shear component of the mechanical displacement is prevailing and does not lead to radiation losses.Работа выполнена при частичной финансовой поддержке грантов РФФИ № 19-07-00300, № 19-07-00304.This research is supported by grant No. 19-07-00300, No. 19-07-00304 from the Russian Foundation for basic research

Антимикробная и антимикотическая фотодинамическая терапия (обзор литературы)

This review highlights the possibilities of photodynamic therapy (PDT) using drugs based on chlorin e6, aluminum phthalocyanine, methylene blue as photosensitizers for bacterial and fungal pathologies. This method was developed initially to treat tumor diseases, where it had shown its high efficiency and safety. Now photodynamic therapy is actively used in the treatment of cancers of the skin, bronchi, stomach, cervix, larynx, or other regions. However, numerous studies have been carried out for the entire existence of the method, demonstrating new possibilities of its application. This review highlights a number of studies in which the efficacy and safety of antimicrobial and antimycotic PDT were studied in vivo and in vitro. It has been proven to have a positive effect on the reparative processes in the wound. An experimental study was carried out to study the effectiveness of photodynamic therapy in the treatment of peritonitis in mice. Demonstrated anti-inflammatory potential in the treatment of autoimmune diseases.В обзоре литературы освещены возможности фотодинамической терапии (ФДТ) с использованием в качестве фотосенсибилизатора (ФС) ряда препаратов, в том числе на основе хлорина е6, фталоцианина алюминия, метиленового синего, при бактериальных и грибковых патологиях. Метод ФДТ изначально был разработан для лечения опухолевых заболеваний, в борьбе с которыми показал свою высокую эффективность и безопасность. В настоящее время ФДТ активно применяется при лечении пациентов с раком кожи, бронхов, желудка, шейки матки, гортани и других локализаций. Однако за все время существования метода были проведены многочисленные исследования, демонстрирующие новые возможности его применения. В настоящем обзоре освещен ряд научно-исследовательских работ, в которых была изучена эффективность и безопасность антимикробной и антимикотической ФДТ в экспериментах in vivo и in vitro. Выполнен обзор публикаций, посвященных изучению механизмов антимикробного действия ФДТ, а также изучающих влияние ФДТ на репаративные процессы в ране. В исследованиях, включенных в настоящий обзор, доказана высокая эффективность антимикробной и антимикотической ФДТ. Продемонстрирован противовоспалительный потенциал метода при лечении аутоиммунных заболеваний у людей

Gas Sensor Based on the Piezoelectric Lateral Electric Field Resonator and a Gas-Sensitive Chitosan Film

Поступила: 27.09.2019. Принята в печать: 10.10.2019.Статья является расширенной версией доклада, представленного на 29-й Международной Крымской конференции «СВЧ-техника и телекоммуникационные технологии» — КрыМиКо’2019 (Севастополь, РФ, 8–14 сентября 2019 г.).Received: 27.09.2019. Accepted: 10.10.2019.В работе исследованы сенсорные свойства датчика, представляющего собой структуру «стеклянная подложка – пленка хитозана – воздушный зазор – резонатор с поперечным возбуждающим электрическим полем (ПЭП)». Резонатор изготовлен из пластины пьезокерамики ЦТС-19 толщиной 2,54 мм и поперечными размерами 20×18 мм2 с двумя прямоугольными алюминиевыми электродами с размерами 20×7 мм2 и зазором между ними 4 мм. Полярная ось была ориентирована перпендикулярно зазору между электродами. В качестве газочувствительных пленок использовались пленки лактата хитозана и гликолята хитозана, сорбционные свойства которых изучались по отношению к парам воды, этанола и водного раствора аммиака (10 %). Установлено, что для обоих типов пленок в присутствии паров указанных жидкостей резонансная частота параллельного резонанса и максимальное значение реальной части электрического импеданса исследуемой структуры существенно уменьшаются и полностью восстанавливаются после удаления паров из камеры.We investigate the gas-sensitive properties of the sensor comprising “glass substrate – chitosan film – air gap – the lateral exciting electric field resonator (LFE)”. The resonator is made using a PZT-19 piezoceramic plate with a thickness of 2.54 mm and shear dimensions of 20×18 mm2 with two rectangular aluminum electrodes with dimensions of 20×7 mm2 and a 4 mm gap between them. The polar axis is oriented perpendicular to the gap between the electrodes. We use films of chitosan lactate and chitosan glycolate, as gas-sensitive films, whose sorption properties are studied in regard to water vapor, ethanol, and aqueous solution of ammonia (10%-wt.). It has been established that the resonance frequency of the parallel resonance and maximum value of the real part of the electrical impedance of the studied structures substantially have decreased for both types of films in the presence of vapors of the test analytes and have been completely restored after removing the vapor from the chamber.Работа выполнена при частичной финансовой поддержке гранта РФФИ № 19-07-00300.The research is completed with partial financial support of the RFBR grant No. 19-07-00300

Impact of milk protein type on the viability and storage stability of microencapsulated Lactobacillus acidophilus using spray drying

Three different milk proteins — skim milk powder (SMP), sodium caseinate (SC) and whey protein concentrate (WPC) — were tested for their ability to stabilize microencapsulated L. acidophilus produced using spray drying. Maltodextrin (MD) was used as the primary wall material in all samples, milk protein as the secondary wall material (7:3 MD/milk protein ratio) and the simple sugars, d-glucose and trehalose were used as tertiary wall materials (8:2:2 MD/protein/sugar ratio) combinations of all wall materials were tested for their ability to enhance the microbial and techno-functional stability of microencapsulated powders. Of the optional secondary wall materials, WPC improved L. acidophilus viability, up to 70 % during drying; SMP enhanced stability by up to 59 % and SC up to 6 %. Lactose and whey protein content enhanced thermoprotection; this is possibly due to their ability to depress the glass transition and melting temperatures and to release antioxidants. The resultant L. acidophilus powders were stored for 90 days at 4 °C, 25 °C and 35 °C and the loss of viability calculated. The highest survival rates were obtained at 4 °C, inactivation rates for storage were dependent on the carrier wall material and the SMP/d-glucose powders had the lowest inactivation rates (0.013 day−1) whilst the highest was observed for the control containing only MD (0.041 day−1) and the SC-based system (0.030 day−1). Further increase in storage temperature (25 °C and 35 °C) was accompanied by increase of the inactivation rates of L. acidophilus that followed Arrhenius kinetics. In general, SMP-based formulations exhibited the highest temperature dependency whilst WPC the lowest. d-Glucose addition improved the storage stability of the probiotic powders although it was accompanied by an increase of the residual moisture, water activity and hygroscopicity, and a reduction of the glass transition temperature in the tested systems