pH-sensitive bilayer electrospun nanofibers based on ethyl cellulose and Eudragit S-100 as a dual delivery system for treatment of the burn wounds; preparation, characterizations, and in-vitro/in-vivo assessment.

A pH-sensitive bilayer electrospun nanofibrous mat containing both antibiotic (gentamicin sulfate, GEN) and non-steroidal anti-inflammatory (diclofenac sodium, DIC) drugs was fabricated for burn wound dressing by electrospinning technique, in which ethyl cellulose (EC) and ethyl cellulose/Eudragit S-100 (EC/ES-100) formed the top and bottom layers, respectively. The fabricated pH-sensitive bilayer electrospun nanofibrous mats were characterized from aspects of both structure and efficiency. Physicochemical properties were investigated via SEM, FTIR, and TGA. The swelling ratio and in vitro drug release of the fabricated nanofibrous mats were studied in different pHs. MTT was applied to assess the safety of the fiber mats. Finally, the in vivo efficiency of the designed pH-sensitive bilayer electrospun nanofibrous mats was examined on the male Wistar rats. Based on the histological analysis and wound healing test (in vivo animal experiments), the (ES100/EC-DIC/GEN)-(EC) pH-sensitive bilayer nanofibrous mat displayed faster wound healing than other bilayer nanofibrous mat. As a result, (ES100/EC-DIC/GEN)-(EC) bilayer nanofibrous mat with pH-responsion could accelerate the burn wound healing process via decreasing the adverse effects of GEN and DIC as topical antimicrobial and anti-inflammatory agents, receptively.

Amphiphilic hyperbranched polyester coated rod mesoporous silica nanoparticles for pH-responsive doxorubicin delivery.

Rod-like mesoporous silica nanoparticles with pH-responsive amphiphilic hyperbranched polyester shells were prepared for doxorubicin (DOX) delivery. First, rod-shaped mesoporous silica nanoparticles (MSNs) were obtained, then hydrophobic hyperbranched polyester Boltorn H40 (H40) was grafted on their surface. The H40 coated MSNs were next treated with amine-functionalized polyethylene glycol (PEG) to achieve the hydrophilic and pH-responsive material denoted as PEG-H40-MSNs. The experimental results showed that PEG-H40-MSNs were successfully synthesized. BET analysis showed that rod MSNs exhibits a type IV standard isotherm. TEM revealed that the thin gray polymer layer was formed around the SBA-15 particle with a diameter of around 150 nm. DOX was effectively loaded, which can be released according to the ambient pH inside the cell as follow: at pH 7.4, only 9.7% of the DOX was released after 48 h; as the pH decreased to 5.5, the cumulative release reached to 49% at the same time. PEG-H40-MSNs showed less than 1.6% of hemolytic activity and a slight effect on the liver and kidney of treated mice were observed at a high disposal dosage implying negligible toxicities were caused by PEG-H40-MSNs in both in vitro hemolysis analysis and in vivo biochemical in mice. However, the in vitro cytotoxicity evaluation of the DOX-PEG-H40-MSNs showed that the cell cytotoxicity of both pure DOX and DOX-loaded PEG-H40-MSNs generally enhanced by increasing the concentration of DOX. Graphical abstract Schematic of cellular uptake and DOX release of PEG-H40-MSNs nanoparticle.