Slow eroding biodegradable multiblock poloxamer copolymers

Ahn, Jin Sun; Suh, Ju Myung; Lee, Minyung; Jeong, Byeongmoon

doi:10.1002/pi.1780

Cited by 41 publications

(41 citation statements)

References 27 publications

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“…4). The increase in modulus and decrease in sol-gel transition temperature by increasing the molecular weight of a polymer were also reported for multiblock poloxamer aqueous solutions [20].…”

Section: Peg-sas Investigated In This Study Are Listed Inmentioning

confidence: 89%

Injectable gel: Poly(ethylene glycol)–sebacic acid polyester

Lee

Joo

et al. 2006

Polymer

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Section: Peg-sas Investigated In This Study Are Listed Inmentioning

confidence: 89%

Injectable gel: Poly(ethylene glycol)–sebacic acid polyester

Lee

Joo

et al. 2006

Polymer

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“…In fact, the gel duration of P85-terephthalate multiblock copolymer increased to >15 days, whereas that of unmodified P85 was <1 day. 49 The 2,5-dicarboxy terephthalate connected multiblock Pluronics aqueous solutions showed a gel state in a pH range of 4À7 and a sol state at low and high pHs. 35 The solubility of PEG in water increases at low pHs, whereas the degree of ionization of 2,5-dicarboxy terephthalate of the multiblock copolymer increases at high pHs.…”

Section: How To Shorten the Dissolution Timementioning

confidence: 99%

Biodegradable Thermogels

et al. 2011

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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.

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“…Pluronic Ò , a non-degradable triblock copolymer of polyethylene glycol-polypropylene glycol-polyethylene glycol (PEG-PPG-PEG), has been used for the synthesis of slow eroding temperature-sensitive multi-block copolymer [22]. This polymer has previously been shown to be able to house and release DNA over an extended period.…”

Section: Introductionmentioning

confidence: 99%