Recent advances in thermogels for the management of diabetic ocular complications

Abstract

Diabetic ocular complications continue to be the leading cause of vision impairment in the world and has a considerable impact to healthcare and the global economy. While there are management...

Poly(l-threonine-co-l-threonine Succinate) Thermogels for Sustained Release of Lixisenatide

“…14−17 The facile control of sol-to-gel transition temperatures and mechanical properties by variations in polymer concentration and composition, minute polymer structural changes, and the addition of external substances are other advantages of thermogels. 18,19 The sol-to-gel transition properties of an aqueous polymer solution can even be tuned by mixing polymers with different transition temperatures. 20,21 Furthermore, the simple mixing of the aqueous polymer solution and drugs for injectable formulation and microfiltration for sterilization are additional advantages of thermogels.…”

“…Since the pioneering research on a poly(lactide- co -glycolide)/poly(ethylene glycol) (PLGA/PEG) system as a biodegradable thermogel, various systems, such as polycaprolactone/PEG, polyphosphazene/PEG, chitosan/glycerol phosphate, glycochitosan hexanol, and PEG/polyester multiblock copolymers, and polypeptide/PEG have been reported for their characteristic transition mechanism and potential biomedical applications. − The sol-to-gel transition mechanism of PLGA/PEG thermogel involves dehydration, followed by hydrophobic aggregation of semibald micelles. , In the case of polypeptide/PEG systems, changes in polypeptide secondary structure as well as dehydration of the PEG block were reported. , Chitosan/glycerol phosphate systems undergo thermogelation through hydrophobic aggregation involving deprotonation of ammonium groups of chitosan and increased ionic strength of phosphate salts . Recently, thermogel composite systems containing nano/microparticles, such as hydroxyapatite, silica, polyhedral oligomeric silsesquioxanes (POSS), and metal–organic framework (MOF) have been investigated to control mechanical properties as well as drug release profiles. − The facile control of sol-to-gel transition temperatures and mechanical properties by variations in polymer concentration and composition, minute polymer structural changes, and the addition of external substances are other advantages of thermogels. , The sol-to-gel transition properties of an aqueous polymer solution can even be tuned by mixing polymers with different transition temperatures. , Furthermore, the simple mixing of the aqueous polymer solution and drugs for injectable formulation and microfiltration for sterilization are additional advantages of thermogels. Various thermogel applications have been reported, including drug delivery, postsurgical adhesion prevention, three-dimensional cell culture, injectable tissue engineering, long-acting anesthetics, and wound dressing. ,− As drug delivery systems, however, thermogels suffer from an initial burst release of hydrophilic drugs, such as polypeptides and protein drugs, due to the partitioning of the drug in the hydrophilic PEG domain of the gel, as well as weak interactions between the drug and polymers.…”

“…Recently, thermogel composite systems containing nano/microparticles, such as hydroxyapatite, silica, polyhedral oligomeric silsesquioxanes (POSS), and metal–organic framework (MOF) have been investigated to control mechanical properties as well as drug release profiles. − The facile control of sol-to-gel transition temperatures and mechanical properties by variations in polymer concentration and composition, minute polymer structural changes, and the addition of external substances are other advantages of thermogels. , The sol-to-gel transition properties of an aqueous polymer solution can even be tuned by mixing polymers with different transition temperatures. , Furthermore, the simple mixing of the aqueous polymer solution and drugs for injectable formulation and microfiltration for sterilization are additional advantages of thermogels. Various thermogel applications have been reported, including drug delivery, postsurgical adhesion prevention, three-dimensional cell culture, injectable tissue engineering, long-acting anesthetics, and wound dressing. ,− As drug delivery systems, however, thermogels suffer from an initial burst release of hydrophilic drugs, such as polypeptides and protein drugs, due to the partitioning of the drug in the hydrophilic PEG domain of the gel, as well as weak interactions between the drug and polymers. For, example, human growth hormone (hGH) was released over 1 week from polypeptide thermogel .…”