An in‐vitro study of the effect of buffer on the degradation of poly(glycolic acid) sutures

Abstract

The tensile strengths of poly(glycolic acid) (PGA) sutures immersed in buffered and unbuffered aqueous media were compared. The media used were an unbuffered physiological saline solution (pH = 5.0) and a phosphate-buffered physiological saline solution (pH = 7.4). PGA samples were immersed for various periods in each medium, and kept at 37 +/- 1 degree C in a constant temperature oven. The tensile strengths of the specimens were tested immediately after removal from the medium. Stress-strain curves of the specimens were expressed in terms of the stress unit "tenacity," commonly used in the study of fibrous polymers; it is an appropriate unit for materials of fibrous nature. These stress-strain curves were investigated as functions of buffering and duration of immersion. Degradation reduced the tensile strength of PGA more in the buffered saline solution than in the unbuffered. This higher rate of degradation in the buffered solution might be due to the presence of Na2HPO4, which removed the degradation products, shifted the reaction toward increased hydrolosis, and accelerated the loss of tensile strength in the PGA. A continuous decrease in the pH of the unbuffered solution supports this explanation. Tied-chain segments of macromolecules, a theory widely used in the study of mechanical strength of fibrous polymer may be the key to a comprehensive description of the degradation phenomenon of PGA.

Mechanism and rate of degradation of polyhydroxyoctanoate films in aqueous media: A long-termin vitro study

“…caused a more rapid loss of tensile strength. 21 In a more detailed study, Makino et al also found that the salt concentration in buffer solutions accelerated ester bond cleavage by converting acidic degradation products into neutral salts. 22 Similar phenomena have been observed with other degradable polymers of the polyamide type 23 and the aliphatic polyester type derived from lactic and glycolic acids (PLAGA).…”

Biodegradation of Absorbable Sutures in Body Fluids and pH Buffers

“…The hydrolysis of ester bonds in the macromolecules is the main responsible mechanism for degradation of sutures [22][23][24]. The influence of temperature and pH on the absorption speed has often been reported and has a chemical explanation [17,22,25]. Cellular activities might play a role on degradation time [26].…”

In vitro hydrolytic degradation of poly(ɛ-caprolactone) grafted dextran fibers and films

“…For example, Pena and co-workers found that PCL films degrade faster in Dulbecco's Modified Eagle's Medium (DMEM) than PBS [20]. Chu and co-workers studied the effect of buffer solutions on PGA suture degradation and concluded that amorphous and crystalline regions had different degradation rates [21,22]. Additionally, in vitro mechanical conditioning has been shown to be critically important in tissue engineering applications [23].…”