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The present paper focuses on the synthesis and characterization of new hydrogels and drug delivery systems, designed for local therapy. The hydrogels were obtained by reacting PEG-ylated chitosan derivatives with citral in different molar ratios of their functionalities. The drug delivery systems were obtained by the in situ hydrogelation of PEG-ylated chitosan derivatives with citral, in the presence of a hydrophilic anti-inflammatory drug, diclofenac sodium salt. The hydrogels and the drug delivery systems were characterized from the structural, supramolecular and morphological points of view by FTIR spectroscopy, wide angle X-ray diffraction, polarized optical microscopy and scanning electron microscopy. The in vitro release kinetics of the drug has been monitored in physiological conditions, while the in vivo release was evaluated by the somatic pain model on rats. The in vitro enzymatic degradability of the hydrogels was evaluated in the presence of lysozyme, leading to a significant mass loss of 47% in 21 days. All the findings, recommend the investigated materials as promising candidates for local drug delivery applications. Unlabelled Image [ABSTRACT FROM AUTHOR]

This paper reports new formulations based on chitosan, citral, and diclofenac sodium salt (DCF). The central idea was to encapsulate an anionic drug into a polycationic hydrogel matrix in order to increase the intermolecular forces between them and thus to ensure slower drug release, while citral was used as a penetration enhancer to assure efficient delivery of the drug. Hydrogels without drug were also synthesized and used as a reference. The structure, morphology, and supramolecular architecture of the drug delivery systems were evaluated by FTIR spectroscopy, scanning electron microscopy, polarized optical microscopy, and wide-angle X-ray diffraction. The drug release kinetics was monitored in vitro by UV-VIS spectroscopy, in physiological conditions, while the enzymatic and hydrolytic degradability of the hydrogels were evaluated in the presence of lysozyme and phosphate buffer saline (PBS), at 37 °C. All of the data revealed that the anionic DCF was strongly anchored into the polycationic matrix and the drug was slowly released over 7 days. Moreover, the release rate can be controlled by simple variation of the molar ratio between the polycationic chitosan and lipophilic citral. [ABSTRACT FROM AUTHOR]

The paper deals with the design and investigation of the morphology, in vitro drug release and biocompatibility of some new formulations based on polyvinyl alcohol boric acid (PVAB) and diclofenac sodium salt (DCF), with the aim to explore the ability of PVAB to act as a matrix for controlled drug delivery systems. A series of three formulations was obtained by mixing the drug and the polymeric matrix in different mass ratios, with high drug content from 10% w/w to 30% w/w. Their structural and supramolecular characterization, performed by FTIR spectroscopy and X-ray diffraction, revealed important physical interactions between the drug and the polymeric matrix. The morphological data, obtained by X-ray diffraction, polarized optical microscopy and scanning electron microscopy revealed the presence of the drug into the PVAB polymeric matrix, as micrometric polycrystals with a mean diameter in the range 10–15 μm, depending on the drug/polymer ratio. The investigation of their surface peculiarities indicated highly hydrophilic surfaces with a water to air contact angle between 29.9 and 41.4 deg and a surface free energy of 45.6–54.2 N/m2. The in vitro release kinetics was monitored by UV-VIS spectroscopy and the cytotoxic effect was investigated in vitro on fibroblasts and HeLa cells. The PVAB proved excellent cytocompatibility, a relative cell viability of the fibroblasts higher than 90% being recorded for concentrations of PVAB up to 7.5% w/v. The drug has been strongly anchored into the electron deficient PVAB matrix, fact which led to its prolonged release up to 5 days. These findings recommend PVAB as a versatile tool for the development of sustained release drug delivery systems with real chances to cross the gap from theory to applications. The biocompatible PVAB polymer led to sustained release drug delivery systems by anchoring the DCF drug into the polymeric matrix through strong physical interactions. Image 1 • Poly(vinyl alcohol boric acid) (PVAB) was used for the development of drug delivery systems. • Diclofenac (DCF) drug was anchored by electrostatic interactions in the polymeric matrix. • The drug delivery systems released the encapsulated drug in a sustained manner. • The evaluation of the PVAB cytotoxicity revealed high potential for bioapplications. [ABSTRACT FROM AUTHOR]

Microbial infections are a serious healthcare related problem, causing several complications and even death. That is why, the development of new drug delivery systems with prolonged effect represents an interesting research topic. This study presents the synthesis and characterization of new hydrogels based on chitosan and three halogenated monoaldehydes. Further, the hydrogels were used as excipients for the development of drug delivery systems (DDS) by the incorporation of fluconazole, an antifungal drug. The systems were structurally characterized by Fourier Transformed Infrared Spectroscopy and Nuclear Magnetic Resonance, both methods revealing the formation of the imine linkages between chitosan and the aldehydes. The samples presented a high degree of ordering at supramolecular level, as demonstrated by WXRD and POM and a good water-uptake, reaching a maximum of 1.6 g/g. The obtained systems were biodegradable, loosing between 38 and 49 % from their initial mass in the presence of lysozyme in 21 days. The ability to release the antifungal drug in a sustained manner for seven days, along with the high values of the inhibition zone diameter, reaching a maximum of 64 mm against Candida parapsilosis for the chlorine containing sample, recommend these systems as promising materials for bioapplications. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract The paper focuses on the synthesis and characterization of new drug delivery systems for local therapy. They were prepared by in situ hydrogelation of chitosan biopolymer with nitrosalicylaldehyde in the presence of a model drug, varying the crosslinking density. The structural, supramolecular and morphological characteristics of the systems were studied by FTIR spectroscopy, X-ray diffraction and, POM and SEM microscopy. In vitro release of the drug has been explored in simulated physiological conditions and in vivo release was investigated by the somatic pain model on rats. Information on the biodegradation of the systems was gain by simulating experiments of enzymatic degradation. The systems were biodegradable and showed a prolonged drug release, assuring an in vivo efficient therapeutic effect over 5 days, with no systemic toxicity. All these findings demonstrated that the new hydrogels based on nitrosalicyl-imine-chitosan provides a practical approach for sustained drug delivery for local chemotherapy. [ABSTRACT FROM AUTHOR]

The present study reports the synthesis and characterization of 12 drug delivery systems (DDS) for the co-delivery of antifungal and antiviral agents. The systems were obtained by an in situ hydrogelation method of 6 chitosan oligomers with values of the polymerization degree between 14 and 51, with 2-formylphenylboronic acid, in the presence of tenofovir. The structural characterization by NMR and FTIR spectroscopy demonstrated the formation of imine linkages, while WXRD revealed the 3D layered architecture of the systems. SEM and POM images demonstrated the uniform distribution of tenofovir into the matrix, while the Zeta potential measurements revealed the strong interactions which develop between system components. The obtained DDSs presented biodegradability, hemocompatibility and in vivo biocompatibility, which along with their ability to release both the drug and the antifungal aldehyde make them promising materials for the treatment of HIV infection and its associated co-infections' symptoms. [Display omitted] [ABSTRACT FROM AUTHOR]