Insulin-Loaded Silk Fibroin Microneedles as Sustained Release System

Abstract

Silk fibroin has widely been used in biomedical applications for its excellent biocompatibility, degradability, and mechanical properties. Microneedles are a suitable method for transdermal drug delivery. In this work, we have prepared microneedles using silk fibroin as the main material and have added proline to change its crystal structure. The fabricated microneedles are nontoxic and degradable and show relatively slow drug release. Our results indicate that the fibroin/proline microneedles can act as carriers of insulin. Fourier transform infrared (FTIR) observations show that the structure of proline-treated fibroin is transformed from random coils to β-sheets. A more regular arrangement is formed between the molecular segments. X-ray diffraction patterns show that proline has good compatibility with fibroin and induces the secondary conformation of the microneedles to a Silk I type structure. The needles have enough strength to pierce the stratum corneum of the skin. In vitro release experiments with insulin indicate that the release time from the microneedles is maintained up to 60 h. This system of delivery may provide a painless and effective route of insulin intake for the treatment of diabetic patients.

Silk/polyols/GOD microneedle based electrochemical biosensor for continuous glucose monitoring

“…The initial breaking strength of microneedle were around 1.4 AE 0.15 N to 0.8 AE 0.12 N, which were strong to penetrate the skin without breaking. 21 It is compulsory for the microneedle to be adequately stable in uid. In order to estimate the in-uid stability of microneedle, the microneedles with different silk/D-sorbitol ratio were incubated in ISF (pH 7.4), at 37 C for 24 hours, and the morphology, mass loss, water uptake and increase in volume of microneedles were tested.…”

“…The silk/polyols microneedles were prepared similarly to those used in our early report, 21 integrating by platinum and silver wires along with GOD immobilized in work electrode. Platinum and silver wires (D ¼ 0.04 mm) were boiled in 4 M sodium hydroxide solution for 20 minutes, 10 M nitric acid solution for 20 minutes, sonicated in DI water (40 C) for 30 minutes, successively, before fabrication.…”

Engineering Microneedles for Therapy and Diagnosis: A Survey

“…By tailoring the structures, materials, and fabrication methods, an appropriate drug delivery system with good drug load and release kinetic performance can be designed for specific applications. Common control strategies can be divided into three categories: (1) adjusting materials' dissolution rate for rapid or sustained drug delivery [137,138], (2) multiplying layers for sequenced delivery [139], and (3) integrating well-designed limiter or accelerator into structure for conditional release [140]. In skin cancer immunotherapy, high efficacy, reasonable inhibitor dose, and controllable and sustained drug-releasing mechanism are desirable.…”

Advances in the Formulations of Microneedles for Manifold Biomedical Applications

“…This result was similar to subcutaneous injection, but the onset of hypoglycemic response and peak plasma insulin levels was slower. To achieve a sustained release of insulin, Wang et al used proline and silk fibroin to prepare MNs . The change of proline ratios would influence the crystallinity of fibroin, thereby changing the needles' swelling capacity in skin.…”