Silver nanoparticles formulations for healing traumatic injuries in oral mucosa of rats.

OBJECTIVE: To evaluate formulations of 1 % silver (Ag) nanoparticles for treating traumatic lesions induced in the oral mucosa of rats, because these lesions are commonly observed in the dental clinic, and their therapeutic forms are scarce. METHODS: Wistar rats were punch-injured (two circular fragments, 4.0 mm in diameter) in the oral mucosa (one on each side), and were treated topically (twice per week) with the treatments/groups including: no injury, control, vehicle, diluted Ag, soluble Ag, and solid Ag. On the 2nd, 7th, and 14th days postinjury, biopsies were collected for immunohistochemistry and biochemical analysis. RESULTS: The group diluted Ag revealed a higher level of inflammatory infiltrate on the 2nd day, whereas solid Ag presented lower levels. The Ag solid group presented higher IL-1ß on the 2nd day and increased IL-10 and TGF-ß1 throughout the follow-up. Moreover, all three Ag groups presented lower levels of oxidative stress markers and, on the 7th day, the diluted Ag and solid Ag groups revealed higher antioxidants. Diluted Ag and soluble Ag groups presented greater blood vessels proliferation, whereas soluble Ag and solid Ag groups revealed greater VEGF on the 2nd and 14th days. Furthermore, all three Ag groups were highlighted during fibroplasia, although collagenesis was similar to that observed in the control group. CONCLUSIONS: Although diluted Ag was noticeable for its important angiogenesis and fibroplasia, solid Ag was the most suitable formulation in healing oral lesions as it efficiently controlled inflammation and oxidative stress, thus favoring angiogenesis and tissue formation.

Synthesis and colloidal characterization of folic acid-modified PEG-b-PCL Micelles for methotrexate delivery.

Hydrophobic drugs, such as methotrexate, are not easily delivered into the human body. Therefore, the use of amphiphilic nanoplatforms to the transport of these drugs through the bloodstream is a challenge. While the hydrophobic region interacts with the drug, the hydrophilic outer layer enhances its bioavailability and circulation time. Poly (ethylene glycol)-block-poly(ε-caprolactone) PEG-b-PCL micelles are biodegradable and biocompatible, allowing its use as a nanocarrier for drug delivery systems. The stealth property of PEG that composes the outer layer of nanoplatforms, makes the micelle unperceivable to phagocytic cells, increasing the circulation time in the human body. In addition, folic acid functionalization enables micelle selectively targeting to cancer cells, improving treatment efficiency and reducing side effects. In this work, PEG-b-PCL copolymer was synthesized by ring opening polymerization (ROP) of the ε-caprolactone with Poly(ethylene glycol) as a macroinitiator and tin(II) 2-ethyl hexanoate as a catalyst. Functionalization of such micelles with folic acid occurred through the modification of the PEG terminal group. The surface modification of the copolymer micelles resulted in higher critical micellar concentration (CMC), increasing approximately 100 times. The synthesis of the copolymers resulted in molecular weight around 3000 g mol-1 with low polydispersity. The polymer micelles have a hydrodynamic diameter in the range of 100-200 nm and the functionalized sample doesn't show aggregation in the considered pH range. High incorporation efficiency was obtained with a minimum percentage of 85%. The drug release profile and linearization from the Peppas model confirmed the interaction of methotrexate with the hydrophobic segment of the copolymer and its release mechanism by relaxation and/or degradation of the chains, making PEG-b-PCL micelles suitable candidates for hydrophobic drug delivery systems.