Quantitative detection of double bonds in hyaluronic acid derivative via permanganate ion reduction

Abstract

The detection of double bonds in polymers exploited as scaffold materials, e.g. hyaluronic acid (HA) derivatives, is crucial for their further applications. The quantity variations of unsaturated units significantly affect the photoinduced crosslinking degree responsible for the mechanical properties of scaffolds. We demonstrate a simple, selective and rapid quantitative method that enables the detection of double bond moieties in polymers. The approach is based on a reaction with potassium permanganate which is spectrophotometrically confirmed. The effect of glycidyl methacrylate concentration and various reaction catalysts introduced at the stage of HA modification, as well as the change of double bond concentration over time, has been investigated using the proposed method. In addition, the developed quantitative method can be utilized for rapid and efficient detection of unreacted double bonds after photopolymerization as a tool for monitoring conversion over time.

Facile Cell-Friendly Hollow-Core Fiber Diffusion-Limited Photofabrication

“…The approach is based on the protocol described by us earlier in Sochilina et al (2019 ). Modification of hyaluronic acid with methacrylate containing reagents was chosen due to the reported mild cytotoxicity of the conjugated groups, simple one-step modification process, and large number of studies covering this type of modification ( Collins and Birkinshaw, 2013 ; Poldervaart et al, 2017 ).…”

“…The double bond concentration in HA after modification with GMA was determined by using the method described by us in Sochilina et al (2019 ). In brief, HAGM was dissolved in deionized water at concentration 5 mg/ml and then added to the standard solution of titrant KMnO 4 (1 ml, 0.25 mg/ml) until the color was changed from purple to brownish yellow.…”

Preparing Modified Hyaluronic Acid with Tunable Content of Vinyl Groups for Use in Fabrication of Scaffolds by Photoinduced Crosslinking

“…The reaction of HA modification was carried out for four days, compared with processes described in literature that were carried out at pH 12 for 5-10 days [21]. This protocol was chosen based on the results of our earlier study [24] in which the DS of the reaction product was monitored on a daily basis during a sixday period. We found that after four days, DS was not changing appreciably during further progress of the reaction.…”

“…The degree of substitution (DS) of HA with vinyl groups was defined as the ratio between the quantity of grafted repeat units with double bonds to the total quantity of disaccharide units in a considered sample. The amount of double bonds that was required to ensure complete reduction of the standard KMnO 4 solution was determined by titrating this standard with a solution of (unbound) GMA, as described in Sochilina et al [24]. The quantity of disaccharide units was determined from the quantity of the analyte mHA that was required for complete reduction of the standard KMnO 4 solution.…”

“…DS can be estimated by IR [23] or 1 H NMR [20,22] spectroscopies; however, the precise determination of DS by these methods is hampered due to high hygroscopicity and the polymeric nature of modified HA (mHA), which contributes to peak broadening and the presence of much noise. Here, we determined DS quanitatively by a titrimetric method involving potassium permanganate, which was developed earlier [24]. DS was used as the parameter that enables comparison between different mHA samples and, accordingly, identifying the effects of reaction conditions on the progress of polymeranalogous reactions.…”