Reverse Thermal Gelation of PAF-PLX-PAF Block Copolymer Aqueous Solution

Kim, Eun Hae; Joo, Min Kyung; Bahk, Kyung Hyun; Park, Min Hee; Chi, Bo; Lee, Young Mi; Jeong, Byeongmoon

doi:10.1021/bm9004436

Cited by 48 publications

(57 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…An order of Ala < Leu < Phe for effectiveness in lowering the sol-to-gel transition temperature and in increasing the β-sheet component of the polypeptide was observed, suggesting that increases in hydrophobicity and β-sheet content lower sol-to-gel transition temperature of the polymer aqueous solution. 59,60 The effect of the polypeptide microsequences on the nanoassembly and thermosensitivity of a polymer aqueous solution was studied using triblock copolymers of poly-(ethylene glycol)-DL-polyalanine-L-polyalanine (PEG-DL-PA-L-PA; EG 44 -DL-A 9 -L-A 9 ) and poly(ethylene glycol)-L-polyalanine-DL-polyalanine (PEG-L-PA-DL-PA; EG 44 -L-A 9 -DL-A 9 ). 61 The PEG-DL-PA-L-PA aqueous solution underwent a sol-to-gelto-squeezed gel transition, whereas the PEG-L-PA-DL-PA aqueous solution underwent a sol-to-gel transition.…”

Section: How To Shorten the Dissolution Timementioning

confidence: 99%

Biodegradable Thermogels

et al. 2011

Self Cite

View full text Add to dashboard Cite

All living creatures respond to external stimuli. Similarly, some polymers undergo conformational changes in response to changes in temperature, pH, magnetic field, electrical field, or the wavelength of light. In one type of stimuli-responsive polymer, thermogel polymers, the polymer aqueous solution undergoes sol-to-gel transition as the temperature increases. Drugs or cells can be mixed into the polymer aqueous solution when it is in its lower viscosity solution state. After injection of the solution into a target site, heating prompts the formation of a hydrogel depot in situ, which can then act as a drug releasing system or a cell growing matrix. In this Account, we describe key materials developed in our laboratory for the construction of biodegradable thermogels. We particularly emphasize recently developed polypeptide-based materials where the secondary structure and nanoassembly play an important role in the determining the material properties. This Account will provide insights for controlling parameters, such as the sol-gel transition temperature, gel modulus, critical gel concentration, and degradability of the polymer, when designing a new thermogel system for a specific biomedical application. By varying the stereochemistry of amino acids in polypeptides, the molecular weight of hydrophobic/hydrophilic blocks, the composition of the polypeptides, the hydrophobic end-capping of the polypeptides, and the microsequences of a block copolymer, we have controlled the thermosensitivity and nanoassembly patterns of the polymers. We have investigated a series of thermogel biodegradable polymers. Polymers such as poly(lactic acid-co-glycolic acid), polycaprolactone, poly(trimethylene carbonate), polycyanoacrylate, sebacic ester, polypeptide were used as hydrophobic blocks, and poly(ethylene glycol) and poly(vinyl pyrrolidone) were used as hydrophilic blocks. To prepare a polymer sensitive to pH and temperature, carboxylic acid or amine groups were introduced along the polymer backbone. The sol-gel transition mechanism involves changes in the secondary structures of the hydrophobic polypeptide and in the conformation of the hydrophilic block. The polypeptide copolymers were stable in the phosphate buffered saline, but the presence of proteolytic enzymes such as elastase, cathepsin B, cathepsin C, and matrix metallopreoteinase accelerated their degradation. We also describe several biomedical applications of biogradable thermogel polymers. One subcutaneous injection of the insulin formulation of thermogel polypeptide copolymers in diabetic rats provided hypoglycemic efficacy for more than 16 days. The thermogels also provided a compatible microenvironment for chondrocytes, and these cells produced biomarkers for articular cartilage such as sulfated glucoaminoglycan (sGAG) and type II collagen. The thermogels were also used as a fixing agent for in situ cell imaging, and cellular activities such as endocytosis were observed by live cell microscopy.

show abstract

Section: How To Shorten the Dissolution Timementioning

confidence: 99%

Biodegradable Thermogels

et al. 2011

Self Cite

View full text Add to dashboard Cite

show abstract

“…17–20 This polymer has been shown to exhibit a sharp, reversible sol–gel transition point at 32 °C, suffciently above room temperature and suffciently below body temperature making it extremely useful for many biomedical applications. 21 Following synthesis and characterization of this polymer system, we investigated the 3D growth of RGCs cultured within this polymer scaffold. The results of this work provide insight into the complex mechanical and chemical environment that supports RGC growth in three dimensions and could have a direct application in cellular replacement therapies for the treatment of RGC-associated ocular neurodegeneration and other neurodegenerative diseases.…”

Section: Introductionmentioning

confidence: 99%

A Self-Assembling Injectable Biomimetic Microenvironment Encourages Retinal Ganglion Cell Axon Extension in Vitro

Laughter

Ammar

Bardill

et al. 2016

ACS Appl. Mater. Interfaces

View full text Add to dashboard Cite

Sensory-somatic nervous system neurons, such as retinal ganglion cells (RGCs), are typically thought to be incapable of regenerating. However, it is now known that these cells may be stimulated to regenerate by providing them with a growth permissive environment. We have engineered an injectable microenvironment designed to provide growth-stimulating cues for RGC culture. Upon gelation, this injectable material not only self-assembles into laminar sheets, similar to retinal organization, but also possesses a storage modulus comparable to that of retinal tissue. Primary rat RGCs were grown, stained, and imaged in this three-dimensional scaffold. We were able to show that RGCs grown in this retina-like structure exhibited characteristic long, prominent axons. In addition, RGCs showed a consistent increase in average axon length and neurite-bearing ratio over the 7 day culture period, indicating this scaffold is capable of supporting substantial RGC axon extension.

show abstract

“…However, the O‐D bending of D 2 O appears at lower wavenumbers than that of H 2 O (Figure S5a in ESI†), enabling in situ analysis of secondary structure. 53 The hydrogel sample was prepared by dissolving the polymer powder in D 2 O by sonication and maintaining the polymer solution at 37 °C overnight prior to analysis. With D 2 O as the background, the characteristic β-sheet absorbance at 1625 cm -1 (amide I) was observed in the FTIR spectrum (Figure 5b and Figure S5b in ESI†), indicating the domination of β-sheets in the secondary structure population in the hydrated gels, which was in agreement with the results from analyses conducted in the solid state.…”

Section: Resultsmentioning

confidence: 99%

Multi-responsive polypeptide hydrogels derived from N-carboxyanhydride terpolymerizations for delivery of nonsteroidal anti-inflammatory drugs

Fan

Wang

et al. 2017

Org. Biomol. Chem.

View full text Add to dashboard Cite

A polypeptide-based hydrogel system, when prepared from a diblock polymer with a ternary copolypeptide as one block, exhibited thermo-, mechano- and enzyme-responsive properties, which enabled the encapsulation of naproxen (Npx) during the sol–gel transition and its release in the gel state. Statistical terpolymerizations of l-alanine (Ala), glycine (Gly) and l–isoleucine (Ile) NCAs at a 1:1:1 feed ratio initiated by monomethoxy monoamino-terminated poly(ethylene glycol) afforded a series of methoxy poly(ethylene glycol)-block-poly(l-alanine-co-glycine-co-l-isoleucine) (mPEG-b-P(A-G-I)) block polymers. β-Sheets were the dominant secondary structures within the polypeptide segements, which facilitated a heat-induced sol–to-gel transition, resulting from the supramolecular assembly of β-sheets into nanofibrils. Deconstruction of the three–dimensional networks by mechanical force (sonication) triggered the reverse gel–to–sol transition. Certain enzymes could accelerate the breakdown of the hydrogel, as determined by in vitro gel weight loss profiles. The hydrogels were able to encapsulate and release Npx over 6 days, demonstrating the potential application of these polypeptide hydrogels as an injectable local delivery system for small molecule drugs.

show abstract

Reverse Thermal Gelation of PAF-PLX-PAF Block Copolymer Aqueous Solution

Cited by 48 publications

References 33 publications

Biodegradable Thermogels

Biodegradable Thermogels

A Self-Assembling Injectable Biomimetic Microenvironment Encourages Retinal Ganglion Cell Axon Extension in Vitro

Multi-responsive polypeptide hydrogels derived from N-carboxyanhydride terpolymerizations for delivery of nonsteroidal anti-inflammatory drugs

Contact Info

Product

Resources

About