Investigating Buffer Effects on Lysozyme Adsorption to Borosilicate Glass

Proteinadsorption refers to the accumulation and adherence of a protein to the surfaceof a solid, but without surface penetration occurring. Proteins can adsorb to avariety of materials that are used in the manufacture, formulation, and storageof protein medicines. This can have unintended consequences such as loss ofexpensive protein product and aggregate formation. Proteinswith low structural and thermal stability can adsorb to interfaces in higherquantities. This study investigates the role ofbuffer composition, and pH on both the adsorption of lysozyme to borosilicateglass and its thermal stability. Using reverse phase HPLC and dynamic scanningfluorimetry, we quantified the amount of adsorbed protein on the substrate andassessed the thermal stability of lysozyme in the bulk solution. The highest amount of adsorbed lysozyme occurred in the sodiumphosphate and histidine-HCl buffers at pH 7.4. Thermal stability analysisshowed that lysozyme had the lowest melt temperature in these buffers. Theresults indicate that lysozyme adsorption and stability may be mediated by pHand ionic strength.