SERS Investigation on Oligopeptides Used as Biomimetic Coatings for Medical Devices

The surface-enhanced Raman scattering (SERS) spectra of three amphiphilic oligopeptides derived from EAK16 (AEAEAKAK)2 were examined to study systematic amino acid substitution effects on the corresponding interaction with Ag colloidal nanoparticles. Such self-assembling molecular systems, known as “molecular Lego”, are of particular interest for their uses in tissue engineering and as biomimetic coatings for medical devices because they can form insoluble macroscopic membranes under physiological conditions. Spectra were collected for both native and gamma-irradiated samples. Quantum mechanical data on two of the examined oligopeptides were also obtained to clarify the assignment of the prominent significative bands observed in the spectra. In general, the peptide–nanoparticles interaction occurs through the COO− groups, with the amide bond and the aliphatic chain close to the colloid surface. After gamma irradiation, mimicking a free oxidative radical attack, the SERS spectra of the biomaterials show that COO− groups still provide the main peptide–nanoparticle interactions. However, the spatial arrangement of the peptides is different, exhibiting a systematic decrease in the distance between aliphatic chains and colloid nanoparticles.

6. Liveliness

‘Liveliness’ studies the new biologically inspired field of active soft matter. Almost any type of soft matter possesses an active form. Using myosin corresponds to making the cross-links of a polymer gel active. However, polymerization itself can be actively driven, as well as the cross-linking between polymers. Bacteria are, within this perspective, an active form of colloid—nanoparticles that can swim. As their shape becomes highly anisotropic, they generate the notion of ‘active liquid crystals’.

Core–Shell Structured Phenolic Polymer@TiO2 Nanosphere with Enhanced Visible-Light Photocatalytic Efficiency

Core–shell structured TiO2 is a promising solution to promote the photocatalytic effectiveness in visible light. Compared to metal or semiconductor materials, polymers are rarely used as the core materials for fabricating core–shell TiO2 materials. A novel core–shell structured polymer@TiO2 was developed by using phenolic polymer (PP) colloid nanoparticles as the core material. The PP nanoparticles were synthesized by an enzyme-catalyzed polymerization in water. A subsequent sol–gel and hydrothermal reaction was utilized to cover the TiO2 shell on the surfaces of PP particles. The thickness of the TiO2 shell was controlled by the amount of TiO2 precursor. The covalent connection between PP and TiO2 was established after the hydrothermal reaction. The core–shell structure allowed the absorption spectra of PP@TiO2 to extend to the visible-light region. Under visible-light irradiation, the core–shell nanosphere displayed enhanced photocatalytic efficiency for rhodamine B degradation and good recycle stability. The interfacial C–O–Ti bonds and the π-conjugated structures in the PP@TiO2 nanosphere played a key role in the quick transfer of the excited electrons between PP and TiO2, which greatly improved the photocatalytic efficiency in visible light.

Anisotropic structural color particles from colloidal phase separation

Structural color materials have been studied for decades because of their fascinating properties. Effects in this area are the trend to develop functional structural color materials with new components, structures, or morphologies for different applications. In this study, we found that the coassembled graphene oxide (GO) and colloid nanoparticles in droplets could form component phase separations, and thus, previously unknown anisotropic structural color particles (SCPs) with hemispherical colloidal crystal cluster and oblate GO component could be achieved. The anisotropic SCPs, as well as their inverse opal hydrogel derivatives, were endowed with brilliant structural colors and controllable capabilities of fixation, location, orientation, and even responsiveness due to their specific structure, morphology, and components. We have also demonstrated that the anisotropic hydrogel SCPs with these features were ideal candidates for dynamic cell monitoring and sensing. These properties indicate that the anisotropic SCPs and their derivatives have huge potential values in biomedical areas.

FABRICACIóN y CARACTERIZACIóN DE SENSORES DE GAS NATURAL (GN) y GAS LICUADO DE PETRóLEO (GLP), BASADOS EN NANOPARTíCULAS DE ZNO

FABRICACIóN y CARACTERIZACIóN DE SENSORES DE GAS NATURAL (GN) y GAS LICUADO DE PETRóLEO (GLP), BASADOS EN NANOPARTíCULAS DE ZNO FABRICATION AND CARACTERIZATION OF NATURAL GAS (NG) AND LIqUEFIED PETROLEUM GAS (LPG) SENSORS, BASED ON ZNO NANOPARTICLES Robert Paria S, Alcides López M, José Solís V. Facultad de Ciencias, Universidad Nacional de Ingeniería, Av. Túpac Amaru 210, Rímac, Lima, Perú Dirección de Investigación y Desarrollo, Instituto Peruano de Energía Nuclear, Av. Canadá 1470, San Borja, Lima DOI: https://doi.org/10.33017/RevECIPeru2010.0004/ RESUMEN Se ha estudiado la influencia de la radiación gamma en una suspensión coloidal de ZnO. Un primer coloide de ZnO se preparó a partir del Zn(CH3COO)2.2H2O, LiOH.H2O y alcohol etílico, mientras que el segundo se preparó a partir del Zn(CH3COO)2.2H2O, NaHO y alcohol propílico. Los coloides de ZnO, fueron irradiados a 30, 50, 75 y 100kGy. Estos coloides irradiados se caracterizaron por Microscopía Electrónica de Transmisión (MET) y Espectroscopía UV-Vis. Se fabricaron películas de ZnO por la técnica spray-pirólisis a partir de los coloides irradiados; estas películas se caracterizaron por difracción de rayos X (DRX). Para evaluar las propiedades eléctricas, se fabricaron películas de ZnO sobre substratos de alúmina impreso con electrodos de oro y este sistema nos sirvió como sensor de gas. El estudio de la dependencia de la conductancia con la temperatura en presencia de aire, revela que la conductividad eléctrica de los sensores varía en función a la composición cristalina, temperatura de operación y la dosis a la cual han sido irradiados los coloides. Diversos patrones de respuesta han sido hallados cuando los sensores son expuestos a Gas Natural (GN) y Gas Licuado de Petróleo (GLP), respuestas típicas de sensores semiconductores tipo n, tipo p y duales han sido encontrados. Palabras clave: Oxido de zinc, coloide, nanopartículas, radiación gamma, sensor de gas. ABSTRACT We have studied the influence of gamma radiation in a colloidal suspension of ZnO. A first ZnO colloid was prepared from Zn(CH3COO) 2.2H2O, LiOH.H2O and ethyl alcohol, while the second was prepared from Zn(CH3COO) 2.2H2O, NaHO and propyl alcohol. The ZnO colloids were irradiated at 30, 50, 75 and 100 kGy. These irradiated colloids were characterized by Transmission Electron Microscopy (TEM) and UV-Vis spectroscopy. ZnO films were produced by spray-pyrolysis technique from irradiated colloids, these films were characterized by X-ray diffraction (XRD). To evaluate the electrical properties of ZnO films, these films were fabricated on alumina substrates with gold electrodes printed and the system served us as gas sensor. The study of the dependence of the conductance with temperature in air, shows that the electrical conductivity of the sensors varies depending on the crystalline composition, operating temperature and the dose at which colloids have been irradiated. Different response patterns were found when the sensors are exposed to Natural Gas (NG) and Liquefied Petroleum Gas (LPG), typical responses of n-type, duals and p-type semiconductor sensors have been found. Keywords: Zinc oxide, colloid, nanoparticles, gamma radiation, gas sensor.