In vivo study of the efficacy of bupivacaine-eluting novel soy protein wound dressings in a rat burn model

Cell viability of novel composite hydrogels loaded with hydroxyapatite for oral and maxillofacial bone regeneration

The development of hydrogels for maxillofacial bone regeneration holds vast potential. However, some challenges need to be addressed to further their application in clinical settings. One challenge is optimizing cell viability. To improve mechanical strength, various materials have been investigated; however, incorporation of these materials within the hydrogel network may affect cell viability. The purpose of this study was to evaluate the cell viability of novel gelatin-alginate composite hydrogels loaded with hydroxyapatite (HA) and nano-hydroxyapatite (n-HA) for maxillofacial bone regeneration. Nine different hydrogels were prepared: three loaded with 0.5%, 1%, and 3% w/v HA; three loaded with 0.25%, 0.5%, and 1% w/v n-HA; one not loaded as a control and two HA and n-HA hydrogels with a lower concentration of the EDC crosslinker. Cell viability of human osteoblasts exposed to the hydrogels as affected by the HA type, size, and concentration, as well as to the crosslinker concentration, was investigated. An Alamar Blue assay was used to evaluate cell viability in the presence of hydrogel extracts and in aqueous solutions (without the hydrogel). A qualitative model was developed for explaining cell viability and growth. Higher percentages of cell viability were observed in the hydrogels loaded with hydroxyapatite as compared with the control. The effect of HA-related parameters, i.e., particle size and concentration, was found to increase the cytotoxic effect, as expressed in lower cell viability. The most favorable composites were the n-HA hydrogels. The incorporation of n-HA in the hydrogel to form a composite seems to be a very promising approach for maxillofacial bone regeneration applications.

Development and Optimization of Chitosan-Hydroxypropyl Methylcellulose In Situ Gelling Systems for Ophthalmic Delivery of Bupivacaine Hydrochloride

The aim of this study was the development and optimization of chitosan and hydroxypropyl methylcellulose (HPMC) in situ gelling systems, loaded with bupivacaine hydrochloride for topical ocular administration. This study is based on the properties of two polymers: chitosan, which has mucoadhesive action and is a pH-sensitive polymer, but also the cellulose derivative hydroxypropyl methylcellulose, a thermosensitive polymer which has mucoadhesive properties and increases the viscosity of systems. The analysis and optimization of in situ gelling systems were performed based on an experimental design and response surface methodology. The following formulation parameters were considered: X1 = chitosan concentration (0.5%, 1%), X2 = HPMC E 5 LV concentration (2%, 5%) and X3 = Chitosan/HPMC E 5 LV ratio (1/1, 2/1). In addition, the parameters to be optimized were represented by the contact angle (CA (°)), viscosity and cumulative percentage of bupivacaine hydrochloride released in vitro. The results indicate that the designed in situ gelling systems are suitable for bupivacaine prolonged ophthalmic release and overcome the principal disadvantages of the liquid’s ocular formulations. An immediate therapeutic effect corresponding to ocular anesthetic installation was assured in the first stage: burst bupivacaine release. In the second phase, the gradual drug release was assured for over 6 h. This drug release profile, together with the corresponding rheological profile and a collection of superficial properties for good ocular adhesion balanced with an adequate hydrophilic character, assured the desired quality of the attributes for the proposed systems. The system, based on chitosan 1%, HPMC E 5 LV 5% and a 1/1 polymer ratio, could be a solution for the proposed formulation of in situ gelling colloidal systems, since the viscosity of the system was within the range of the optimal viscosity of the eye, and the amount of bupivacaine hydrochloride released after 6 h was the highest at 69.55%.