ABSTRACT
The transdermal drug delivery based on microneedles (MNs) provides a suitable and painless self-administration for diabetic patients. In this work, the hydrogel-forming MNs were firstly fabricated using poly(vinyl alcohol) (PVA) and chitosan (CS) as matrix. A hypoglycemic drug, metformin (Met), had been loaded into MIL-100(Fe). Then, both of free Met and Met-loaded MIL-100(Fe) were integrated into hydrogel-forming MNs for regulation of blood glucose levels (BGLs) on diabetic rats. After penetrated into the skin, the free Met could be firstly released from MNs. Due to the absorption of interstitial fluid and subsequent release of loaded Met from MIL-100(Fe), leading to a sustainable and long-term drug release behaviors. A notable hypoglycemic effect and low risk of hypoglycemia could be obtained on diabetic rat modelsin vivo. The as-fabricated hydrogel-forming MNs expected to become a new type of transdermal drug delivery platform for transdermal delivery of high-dose drugs to form a long-term hypoglycemic effect.
Subject(s)
Administration, Cutaneous , Blood Glucose , Diabetes Mellitus, Experimental , Drug Delivery Systems , Hydrogels , Hypoglycemic Agents , Metformin , Needles , Animals , Metformin/administration & dosage , Blood Glucose/analysis , Rats , Hypoglycemic Agents/administration & dosage , Hypoglycemic Agents/pharmacokinetics , Diabetes Mellitus, Experimental/drug therapy , Hydrogels/chemistry , Male , Polyvinyl Alcohol/chemistry , Chitosan/chemistry , Rats, Sprague-Dawley , Skin/metabolism , Drug LiberationABSTRACT
In this paper, Ni60/WC wear-resistant coatings have been created on the Ti6Al4V substrate surface using a pre-layered powder laser cladding method by deploying various scanning speeds of 8, 10, 12, and 14 mm/s. The coatings are characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), and a high-speed reciprocating fatigue wear tester. It is found that the phase composition of the coating comprises the synthesized, hard phase TiC and TiB2, the silicides WSi2 and W5Si3, and NiTi and γ-Ni solid solutions. At different scanning speeds, there is a metallurgical fusion line in the bonding area of the fused cladding layer, indicating a good metallurgical bonding between the substrate and the powder. At a low scanning speed, the coating develops into coarse dendrites, which shows significant improvement with scanning speed. The microhardness first increases and then decreases with the scanning speed, and the coating's average microhardness was 2.75-3.13 times higher than that of the substrate. The amount of mass wear has been reduced by 60.1-79.7% compared to the substrate. The wear behavior of the coatings was studied through detailed analysis of wear surfaces' microstructures and the amount of wear to identify the optimum scanning speed.
