Electrochemically triggered release of human insulin from an insulin-impregnated reduced graphene oxide modified electrode

Abstract

An electrochemical insulin-delivery system based on reduced graphene oxide impregnated with insulin is described. Upon application of a potential pulse of -0.8 V for 30 min, up to 70 ± 4% of human insulin was released into a physiological medium while preserving its biological activity.

Photothermally triggered on-demand insulin release from reduced graphene oxide modified hydrogels

“…This is in contrast to insulin loading onto GO where higher insulin loading was achieved at pH < 5, as below pH 5.4 insulin is positively charged and interacts more strongly with the negatively charged GO [6]. This is also different from the case of rGO where no pH dependent loading was observed [7] as π − π stacking interactions, being pH independent were believed to prevail between insulin and rGO. In addition, no significant influence of the pH on the swelling ratio of the hydrogel was observed (Fig.…”

“…The good heating capacity of PEGDMA-rGO patches with a rGO content of > 0.4 mg results on the other hand on an efficient insulin release from the patch between 38 and 51% (corresponding to a solution concentrations reaching 6.5-8.7 μM). The photothermal triggered release is comparable to the electrochemical release of ≈ 7 μM insulin [7]. To decrease diabetic blood glucose concentrations to normal levels, 250-330 nM of insulin is needed [30].…”

“…These loadings are higher as compared to that obtained by mixing rGO (1 mg/mL) with human insulin (0.1 mg/mL) where a loading of 55% was reached [7]. The 3-D structure of the hydrogel seems to be favorable for the integration of insulin.…”

“…These smart drug carriers offer important advantages over systematically administered drugs as they are able to overcome problems associated with drug solubility and stability and allow accumulation and release of the therapeutics at selected locations [1][2][3][4][5][6]. Among the different smart drug carriers such as liposomes, microspheres or hydrogels, graphene-based materials are emerging nanostructures for drug delivery [3,[6][7][8][9][10][11]. The high specific surface area of graphene combined with the various interactions offered by this material (π-π stacking, electrostatic, hydrophobic interactions, hydrogen bonding) are beneficial for achieving high drug loading of poorly soluble drugs without compromising potency or efficiency [6,[12][13][14].…”

“…Insulin amidated pectin hydrogels were recently proposed as insulin delivery platforms by Hadebe et al [25]. We have recently exploited the good electrical properties of rGO thin films for efficient electrochemical release of human insulin from rGO-modified electrodes [7]. Thermally modulated insulin release approaches have to be added to the list [9,10,26].…”