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Sat Sep 30, 2017, 10:18 AM

Biodegradable Hydrogels for Glucose Sensitive Insulin Delivery to Treat Diabetics.

Insulin is not a cure for Type I diabetes; it is a treatment. The distinction is important for this disease which, unlike type II diabetes which strikes older people, tends to strike people in their childhood.

A diagnosis of Type I insulin dependent diabetes means, at best, a life time of carefully monitoring one's own blood for glucose concentrations, and repeatedly, as appropriate, injecting one's self with insulin. A miscalculation can lead to hypoglycemia and sometimes serious health effects.

Many alternative ways of delivering insulin have been explored, and a few commercialized, but needles remain the main way of addressing the disease, and moreover, it is not always easy to calibrate the times at which one needs or needs to avoid such an injection.

It would be nice if there were a method for delivering insulin in a way that was responsive to sugar concentrations. Thus it was encouraging to come across a paper published in the scientific journal ACS Applied Materials and Interfaces, this one:

Supersensitive Oxidation-Responsive Biodegradable PEG Hydrogels for Glucose-Triggered Insulin Delivery (Li et al ACS Appl. Mater. Interfaces, 2017, 9 (31), pp 2590525914)

The authors write thusly:

Hydrogels have been investigated extensively and utilized widely in the fields of biotechnology, regenerative medicine, pharmaceutics, and personal hygiene.1−4 In the past two decades, responsive hydrogels have attracted particular attention owing to their great promise for delivery of drugs and bioactive macromolecules,5−7 sensing,8,9 diagnosis,10 bioanalysis and bioseparation,11,12 cell culture or tissue engineering,13,14 and so forth. Although various physical or (bio)chemical stimuli, including temperature, pH, light, enzymes or other biomolecules, reduction or electrochemical redox potential, mechanical force, and magnetic field, have been applied as triggers to induce the formation, change in shape or morphology, and degradation or dissociation of hydrogels,15−17 there are only a few papers on oxidation-responsive polymeric hydrogels that suffer from the weaknesses of low sensitivity or low response rate toward reactive oxygen species (ROS) or low mechanical strength...

... Although a number of papers report polymeric or supramolecular hydrogels that contain phenylboronic acid/ ester moieties, a majority of them are associated with the glucose- or pH-sensitivities of these hydrogels.43−50 Recently, Hamachi and co-workers have reported H2O2-responsive supramolecular hydrogels formed by self-assembly of the hydrophobic p-boronophenyl methoxycarbonyl-capped di- or tripeptides. By incorporating various oxidative enzymes, such as glucose oxidase (GOx), into these hydrogels, they demonstrated a simple strategy for constructing, without tedious synthesis, soft materials responsive to various biochemical stimuli, such as glucose.51,52 Their works greatly expanded the applications of oxidation-responsive hydrogels. In this article, we describe a novel kind of oxidationresponsive hydrogels that were fabricated by the redox-initiated radical polymerization of a 4-arm-poly(ethylene glycol) (PEG) macromonomer having H2O2-cleavable acrylic bonds at the chain ends (Scheme 1). The hydrogels can be degraded by H2O2 via the sequential oxidation and 1,6-/1,4-elimination of the phenylboronic acid linker.53 These hydrogels are designed to be biocompatible and extremely sensitive to H2O2 because they were composed of hydrophilic PEG network and a small fraction (<10 wt %) of hydrophobic but highly sensitive linkers.54

The authors have only tested their hydrogen in vitro, it's degradation by glucose, as well as it's cytotoxicity against cultured cells.

I would imagine that their tox work will be significant, both in China and in the US if they bring the product here. Thus any commercial application is at least a decade off. It's interesting work though, and one hopes that if not this product, similar products will become available to serve as quasi-synthetic pancreases.

Their work was supported by the National Science Foundation of China, China being a government that unlike the current US government, does not hate science and scientists.

Enjoy the weekend.

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