Thermogelling properties of purified poloxamer 407

Abstract

Poloxamers are triblock copolymers with a center block of hydrophobic polypropylene oxide (PPO) flanked by two hydrophilic polyethyleneoxide (PEO) blocks. Among this family of copolymers, poloxamer 407 is a non-ionic surfactant with reversible gelation properties above a particular polymer concentration and a particular temperature. Easy preparation of poloxamer 407 based sterile injectable formulations have made this copolymer a good candidate for drug delivery, specifically when controlled release of the drug is required. Previously, the applications of compendial poloxamer 407 preparations were demonstrated; however, low viscosity, poor elasticity, and sol-to-gel transition temperature (Tsol-gel) over a wide temperature range were observed. A purification process was introduced to eliminate impurities and low molecular weight copolymer molecules from the compendial poloxamer 407 resulting in higher viscosity values with Tsol-gel in a narrow temperature range. Here, poloxamer 407 was purified based on the proposed process and the rheological and analytical evaluation of the purified poloxamer 407 was conducted and compared to unpurified, compendial poloxamer 407. Then, the impact of poloxamer 407 concentration on gel formation was evaluated. For drug delivery applications, the effect of relevant buffer salts and the effect of addition of ethanol to the poloxamer 407 solutions were rheologically evaluated.

PF-127 hydrogel plus sodium ascorbyl phosphate improves Wharton’s jelly mesenchymal stem cell-mediated skin wound healing in mice

“…Tissue engineering-based strategy demonstrates that the utilization of biomaterial-based scaffolds as stem cell delivery and retention platforms can enhance the therapeutic efficiency of stem cells on wound regeneration [14][15][16]. Pluronic F-127 (PF-127, also known as poloxamer 407), a FDA-approved synthetic copolymer made of poly (ethylene oxide)-poly (propylene oxide)-poly (ethylene oxide), is injectable, biodegradable, and thermo-reversible [17,18]. Recent evidences have shown the therapeutic effects of PF-127 used as a scaffold for drug delivery, extracellular vesicles, and cell encapsulation in tissue engineering [19][20][21].…”

Modifying the Properties of Thermogelling Poloxamer 407 Solutions through Covalent Modification and the Use of Polymer Additives

“…The authors suggest that analytical techniques which characterize nanostructure be combined with spectroscopy to elucidate intermolecular interactions to build a full understanding of these complex phenomena. (PIBCA) 10 mg mL −1 21 21 20 kPa a) 18 kPa a) [94] P407 20% w/w (PIBCA) 20 mg mL −1 21 20 20 kPa 17 kPa a)…”

“…P407, when in a 20% w/w solution, transforms from a relatively low viscosity solution below approximately 20 °C to a clear gel when warmed above this critical temperature. This makes it attractive for applications including injectable and topical pharmaceutical formulations, where the material may flow through an applicator or syringe before forming a gel upon contact with the body (35–37 °C) . These gels are also attractive for drug delivery because the material is chemically stable, even in the presence of acids, alkalis, and metal ions .…”

“…This makes it attractive for applications including injectable and topical pharmaceutical formulations, where the material may flow through an applicator or syringe before forming a gel upon contact with the body (35-37 °C). [21] These gels are also attractive for drug delivery because the material is chemically stable, even in the presence of acids, alkalis, and metal ions. [2] P407 is known to be well-tolerated by humans, and has already been approved by the FDA in licensed medicines, evidenced by listing in the inactive ingredients database.…”

Thermophoresis in self-associating systems: probing poloxamer micellization by opto-thermal excitation

“…41 P407 has a molecular weight M w 12600 Da and a nominal composition EO 99 PO 65 EO 99 , but it should be noticed that standard synthesis methods yield polymer chains with a polydispersity of about 10% in the number of EO and PO groups, mostly due to the presence of a small fraction of lower molecular weight EO-PO di-block copolymers. Polydispersity is known to affect the phase boundary and the mechanical properties of the gel phase, 42 but has a much weaker effect on the micellar association properties at lower concentration. 39,43 Sometimes called 'monomers', although in the context of polymers this term can be misleading.…”