scholarly journals Effect of Dexamethasone on Thermoresponsive Behavior of Poly(2-Oxazoline) Diblock Copolymers

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1357
Author(s):  
Monika Majerčíková ◽  
Peter Nádaždy ◽  
Dušan Chorvát ◽  
Leonid Satrapinskyy ◽  
Helena Valentová ◽  
...  
Keyword(s):  
Biomedical Applications ◽  
Diblock Copolymers ◽  
Polarized Light ◽  
Drug Carriers ◽  
Thermoresponsive Polymers ◽  
X Ray Scattering ◽  
Small Series ◽  
Cloud Point Temperature ◽  
Crystalline Nature ◽  
Chain Lengths

Thermoresponsive polymers play an important role in designing drug delivery systems for biomedical applications. In this contribution, the effect of encapsulated hydrophobic drug dexamethasone on thermoresponsive behavior of diblock copolymers was studied. A small series of diblock copoly(2-oxazoline)s was prepared by combining thermoresponsive 2-n-propyl-2-oxazoline (nPrOx) and hydrophilic 2-methyl-2-oxazoline (MeOx) in two ratios and two polymer chain lengths. The addition of dexamethasone affected the thermoresponsive behavior of one of the copolymers, nPrOx20-MeOx180, in the aqueous medium by shifting the cloud point temperature to lower values. In addition, the formation of microparticles containing dexamethasone was observed during the heating of the samples. The morphology and number of microparticles were affected by the structure and concentration of copolymer, the drug concentration, and the temperature. The crystalline nature of formed microparticles was confirmed by polarized light microscopy, confocal Raman microscopy, and wide-angle X-ray scattering. The results demonstrate the importance of studying drug/polymer interactions for the future development of thermoresponsive drug carriers.

scholarly journals Phase Transitions in Poly(vinylidene fluoride)/Polymethylene-Based Diblock Copolymers and Blends

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2442
Author(s):  
Nicolás María ◽  
Jon Maiz ◽  
Daniel E. Martínez-Tong ◽  
Angel Alegria ◽  
Fatimah Algarni ◽  
...  
Keyword(s):  
Diblock Copolymers ◽  
Vinylidene Fluoride ◽  
Polarized Light ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Preparation Conditions ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Poly Vinylidene Fluoride ◽  
Ray Scattering

The crystallization and morphology of two linear diblock copolymers based on polymethylene (PM) and poly(vinylidene fluoride) (PVDF) with compositions PM23-b-PVDF77 and PM38-b-PVDF62 (where the subscripts indicate the relative compositions in wt%) were compared with blends of neat components with identical compositions. The samples were studied by SAXS (Small Angle X-ray Scattering), WAXS (Wide Angle X-ray Scattering), PLOM (Polarized Light Optical Microscopy), TEM (Transmission Electron Microscopy), DSC (Differential Scanning Calorimetry), BDS (broadband dielectric spectroscopy), and FTIR (Fourier Transform Infrared Spectroscopy). The results showed that the blends are immiscible, while the diblock copolymers are miscible in the melt state (or very weakly segregated). The PVDF component crystallization was studied in detail. It was found that the polymorphic structure of PVDF was a strong function of its environment. The number of polymorphs and their amount depended on whether it was on its own as a homopolymer, as a block component in the diblock copolymers or as an immiscible phase in the blends. The cooling rate in non-isothermal crystallization or the crystallization temperature in isothermal tests also induced different polymorphic compositions in the PVDF crystals. As a result, we were able to produce samples with exclusive ferroelectric phases at specific preparation conditions, while others with mixtures of paraelectric and ferroelectric phases.

Physicochemical Characterization of Solid Dispersions of Cefdinir with PVP K-30 and PEG 4000

2010 ◽  
Vol 3 (2) ◽  
pp. 948-956
Author(s):  
Kumar P ◽  
S Kumar ◽  
A Kumar ◽  
M Chander
Keyword(s):  
Solid Dispersions ◽  
Physicochemical Characterization ◽  
Drug Carriers ◽  
Dissolution Properties ◽  
Rate Of Dissolution ◽  
Peg 4000 ◽  
Release Studies ◽  
Crystalline Nature ◽  
Physical Mixtures

The purpose of this study was to prepare and characterize solid dispersions of the antibacterial agent Cefdinir with PEG 4000 and PVP K-30 with a view to improve its dissolution properties. Investigations of the properties of the dispersions were performed using release studies, X-ray powder diffraction (XRD) and Fourier transform infrared (FTIR). The results obtained showed that the rate of dissolution of Cefdinir was considerably improved when formulated in solid dispersions with PVP K-30 and PEG 4000 as compared with pure drug and physical mixtures. The results from XRD studies showed the transition of crystalline nature of drug to amorphous form, while FTIR studies demonstrated the absence of drug-carriers interaction.

scholarly journals Thermal Behaviour of Common Thermoresponsive Polymers in Phosphate Buffer and in Its Salt Solutions

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 90
Author(s):  
Łukasz Otulakowski ◽  
Maciej Kasprów ◽  
Aleksandra Strzelecka ◽  
Andrzej Dworak ◽  
Barbara Trzebicka
Keyword(s):  
Thermal Behaviour ◽  
Phosphate Buffer ◽  
Pure Water ◽  
Thermal Response ◽  
The Body ◽  
Solution Temperature ◽  
Thermoresponsive Polymers ◽  
Aqueous Polymer ◽  
Cloud Point Temperature ◽  
Size Of Particles

Thermoresponsive polymers are a promising material for drug nanocarrier preparation, which makes the study of their aggregation in physiological conditions very important. In this paper, the thermal behaviour of the thermoresponsive polymers poly(N-isopropylacrylamide), poly(2-isopropyl-2-oxazoline-co-2-n-propyl-2-oxazoline) and poly[(2-hydroxyethyl methacrylate)-co-oligo(ethylene glycol) methyl ether methacrylate] were studied in phosphate buffer (PBS) and solutions of its salts in concentration as in PBS. The thermal response of the polymers was measured using UV-Vis and dynamic light scattering (DLS). The salts shifted the cloud point temperature (TCP) of the (co)polymers to higher values compared to the TCP of aqueous polymer solutions. In PBS and NaCl solutions, all polymers exhibited an unexpected and previously unreported transmittance profile. During heating, an additional aggregation of polymers appeared above the TCP accompanied by the formation of a precipitate. In monosodium phosphate solutions and pure water, the studied polymers showed lower critical solution temperature (LCST-type) behaviour. DLS measurements showed that a salt influenced the size of the resulting polymer particles. The sizes and stability of particles depended on the heating rate. In PBS and NaCl solutions, the size of particles in the dispersion decreased above 60 °C, and the precipitate appeared on the bottom of the cuvette. The additional aggregation of polymer and its falling out of solution may hinder the removal of carriers from the body and has to be taken into account when preparing nanocarriers.

scholarly journals Effect of tungsten disulfide nanotubes on crystallization of polylactide under uniaxial deformation and annealing

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Fausta Loffredo ◽  
Loredana Tammaro ◽  
Tiziana Di Luccio ◽  
Carmela Borriello ◽  
Fulvia Villani ◽  
...  
Keyword(s):  
Biomedical Applications ◽  
Structural Evolution ◽  
Tungsten Disulfide ◽  
Fine Tuning ◽  
Nanocomposite Films ◽  
Uniaxial Deformation ◽  
Scanning Calorimetry ◽  
X Ray ◽  
X Ray Scattering

AbstractTungsten disulfide (WS2) nanotubes (NTs) are examined here as a filler for polylactide (PLA) for their ability to accelerate PLA crystallization and for their promising biocompatibility in relevant to biomedical applications of PLA-WS2 nanocomposites. In this work, we have studied the structural and thermal properties of PLA-WS2 nanocomposite films varying the concentration of WS2 NTs from 0 (neat PLA) to 0.6 wt%. The films were uniaxially drawn at 90 °C and annealed at the same temperature for 3 and 10 min. Using wide angle x-ray scattering, Raman spectroscopy and differential scanning calorimetry, we probed the effects of WS2 NT addition on the structure of the PLA films at various stages of processing (unstretched, stretching, annealing). We found that 0.6 wt% of WS2 induces the same level of crystallinity in as stretched PLA-WS2 as annealing in neat PLA for 10 min. These data provide useful insights into the role of WS2 NTs on the structural evolution of PLA-WS2 composites under uniaxial deformation, and extend their applicability to situations where fine tuning of PLA crystallinity is desirable.

scholarly journals Vibrational resonant inelastic X-ray scattering in liquid acetic acid: a ruler for molecular chain lengths

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Viktoriia Savchenko ◽  
Iulia Emilia Brumboiu ◽  
Victor Kimberg ◽  
Michael Odelius ◽  
Pavel Krasnov ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Acetic Acid ◽  
Molecular Chain ◽  
X Ray ◽  
X Ray Scattering ◽  
Localized Excitations ◽  
Vibrational Excitations ◽  
Chain Lengths ◽  
X Ray Absorption ◽  
Ray Scattering

AbstractQuenching of vibrational excitations in resonant inelastic X-ray scattering (RIXS) spectra of liquid acetic acid is observed. At the oxygen core resonance associated with localized excitations at the O–H bond, the spectra lack the typical progression of vibrational excitations observed in RIXS spectra of comparable systems. We interpret this phenomenon as due to strong rehybridization of the unoccupied molecular orbitals as a result of hydrogen bonding, which however cannot be observed in x-ray absorption but only by means of RIXS. This allows us to address the molecular structure of the liquid, and to determine a lower limit for the average molecular chain length.

scholarly journals Preparation and Sustained-Release Performance of PLGA Microcapsule Carrier System

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1758
Author(s):  
Shuaikai Ren ◽  
Chunxin Wang ◽  
Liang Guo ◽  
Congcong Xu ◽  
Yan Wang ◽  
...  
Keyword(s):  
Controlled Release ◽  
Biomedical Applications ◽  
Encapsulation Efficiency ◽  
Drug Carriers ◽  
Optimum Conditions ◽  
Carrier System ◽  
Preparation Conditions ◽  
Encapsulation Rate ◽  
Release Drug ◽  
Release Curve

Microcapsules have been widely studied owing to their biocompatibility and potential for application in various areas, particularly drug delivery. However, the size of microcapsules is difficult to control, and the size distribution is very broad via various encapsulation techniques. Therefore, it is necessary to obtain microcapsules with uniform and tailored size for the construction of controlled-release drug carriers. In this study, emulsification and solvent evaporation methods were used to prepare a variety of ovalbumin-loaded poly (lactic-co-glycolic acid) (PLGA) microcapsules to determine the optimal preparation conditions. The particle size of the PLGA microcapsules prepared using the optimum conditions was approximately 200 nm, which showed good dispersibility with an ovalbumin encapsulation rate of more than 60%. In addition, porous microcapsules with different pore sizes were prepared by adding a varying amount of porogen bovine serum albumin (BSA) to the internal water phase. The release curve showed that the rate of protein release from the microcapsules could be controlled by adjusting the pore size. These findings demonstrated that we could tailor the morphology and structure of microcapsules by regulating the preparation conditions, thus controlling the encapsulation efficiency and the release performance of the microcapsule carrier system. We envision that this controlled-release novel microcapsule carrier system shows great potential for biomedical applications.

scholarly journals Deep learning-based estimation of Flory–Huggins parameter of A–B block copolymers from cross-sectional images of phase-separated structures

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Katsumi Hagita ◽  
Takeshi Aoyagi ◽  
Yuto Abe ◽  
Shinya Genda ◽  
Takashi Honda
Keyword(s):  
Deep Learning ◽  
Diblock Copolymers ◽  
Three Dimensional ◽  
Image Data ◽  
Real Space ◽  
Cross Sectional ◽  
Regression Problem ◽  
Self Consistent Field ◽  
Experimental Image ◽  
Chain Lengths

AbstractIn this study, deep learning (DL)-based estimation of the Flory–Huggins χ parameter of A-B diblock copolymers from two-dimensional cross-sectional images of three-dimensional (3D) phase-separated structures were investigated. 3D structures with random networks of phase-separated domains were generated from real-space self-consistent field simulations in the 25–40 χN range for chain lengths (N) of 20 and 40. To confirm that the prepared data can be discriminated using DL, image classification was performed using the VGG-16 network. We comprehensively investigated the performances of the learned networks in the regression problem. The generalization ability was evaluated from independent images with the unlearned χN. We found that, except for large χN values, the standard deviation values were approximately 0.1 and 0.5 for A-component fractions of 0.2 and 0.35, respectively. The images for larger χN values were more difficult to distinguish. In addition, the learning performances for the 4-class problem were comparable to those for the 8-class problem, except when the χN values were large. This information is useful for the analysis of real experimental image data, where the variation of samples is limited.

Thermotropic behavior of sodium cholesteryl carbonate

2009 ◽  
Vol 24 (1) ◽  
pp. 156-163 ◽  
Author(s):  
Rabkwan Chuealee ◽  
Timothy S. Wiedmann ◽  
Teerapol Srichana
Keyword(s):  
Phase Behavior ◽  
Chemical Structure ◽  
Liquid Crystalline ◽  
Polarized Light ◽  
Wave Number ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
X Ray Scattering ◽  
C Nmr

Sodium cholesteryl carbonate ester (SCC) was synthesized, and its phase behavior was studied. The chemical structure was assessed by solid-state infrared spectroscopy based on vibration analysis. The wave number at 1705 and 1276 cm−1 corresponds to a carbonyl carbonate and O–C–O stretching of SCC, respectively. Molecular structure of SCC was further investigated with 1H and 13C NMR spectroscopy. The chemical shift, for the carbonyl carbonate resonance appeared at 155.5 ppm. A molecular mass of SCC was at m/z of 452. Differential scanning calorimetry (DSC), video-enhanced microscopy (VEM) together with polarized light microscopy, and small-angle x-ray scattering (SAXS) were used to characterize the phase behavior as a function of temperature of SCC. Liquid crystalline phase was formed with SCC. Based on the thermal properties and x-ray diffraction, it appears that SCC forms a structure analogous to the type II monolayer structure observed with cholesterol esters.

scholarly journals Special Section Guest Editorial: Polarized Light for Biomedical Applications

2016 ◽  
Vol 21 (7) ◽  
pp. 071001 ◽  
Author(s):  
Tatiana Novikova ◽  
Igor Meglinski ◽  
Jessica C. Ramella-Roman ◽  
Valery V. Tuchin
Keyword(s):  
Biomedical Applications ◽  
Guest Editorial ◽  
Special Section ◽  
Polarized Light

scholarly journals Chitosan-Based Biocompatible Copolymers for Thermoresponsive Drug Delivery Systems: On the Development of a Standardization System

Pharmaceutics ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1876
Author(s):  
Lorenzo Marsili ◽  
Michele Dal Bo ◽  
Federico Berti ◽  
Giuseppe Toffoli
Keyword(s):  
Drug Delivery ◽  
Biomedical Applications ◽  
Biological Tissues ◽  
Special Focus ◽  
Thermoresponsive Polymers ◽  
Basic Principles ◽  
Natural Polysaccharide ◽  
Non Covalent Interactions ◽  
Covalent Interactions ◽  
Or Applications

Chitosan is a natural polysaccharide that is considered to be biocompatible, biodegradable and non-toxic. The polymer has been used in drug delivery applications for its positive charge, which allows for adhesion with and recognition of biological tissues via non-covalent interactions. In recent times, chitosan has been used for the preparation of graft copolymers with thermoresponsive polymers such as poly-N-vinylcaprolactam (PNVCL) and poly-N-isopropylamide (PNIPAM), allowing the combination of the biodegradability of the natural polymer with the ability to respond to changes in temperature. Due to the growing interest in the utilization of thermoresponsive polymers in the biological context, it is necessary to increase the knowledge of the key principles of thermoresponsivity in order to obtain comparable results between different studies or applications. In the present review, we provide an overview of the basic principles of thermoresponsivity, as well as a description of the main polysaccharides and thermoresponsive materials, with a special focus on chitosan and poly-N-Vinyl caprolactam (PNVCL) and their biomedical applications.

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