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Assessing the effect of formulation composition on spidroin charge and stability

Assessing the effect of formulation composition on spidroin charge and stability

Work performed in conjunction with Spiber Technologies, Uppsala, Sweden. Use of dynamic and electrophoretic light scattering to assess the effects of protein formulation composition


Spidroins are a unique family of large, structural proteins that make up the bulk of spider silk fibers. The mechanical strength and elasticity of spider silk fibers have led to their successful use in the regeneration of peripheral nerves in rats [1]. Recombinant spider silk proteins have also shown potential for use in drug delivery systems [2]. Despite the wide range of medical applications that spider silk proteins offer, the production of these proteins on an industrial scale has only become possible fairly recently.

The evolution of spidroins has been influenced strongly by a requirement for high tensile strength, a quality that does not necessarily guarantee conformational or chemical stability when other stresses are applied. This application note describes the use of a Zetasizer Nano ZSP to characterize the charge state of spidroins in different formulations. The earliest stages of spidroin aggregation in different formulations are then assessed using low-temperature dynamic light scattering (DLS) thermal trend experiments.


The zeta potential of spidroin samples was determined on a Zetasizer Nano ZSP using folded capillary cells. All electrophoretic light scattering (ELS) measurements were acquired using a fixed voltage of 75 V, or, given that the distance between the electrodes of a folded capillary cell is 6 cm, an electric field strength of 12.5 V/cm. A monomodal analysis model was applied, fast field reversal analysis being carried out alone on the samples in order to minimize the effect of joule heating. All ELS measurements were acquired at 25 °C after allowing for thermal equilibration of samples.

Samples were heated from 4 °C to 21 °C, with measurements acquired at temperature intervals of 1 °C. The system was purged with dry air during thermal trend experiments in order to minimize condensation on the cuvette wall.

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