Characterised biopolymers

Wyatt Technology has combined its instruments to explore the material characteristics of the biopolymer, hyaluronic acid.

Using its ViscoStar, Dawn EOS and Optilab rEX in series, Wyatt has overcome consistent problems experienced using other techniques to accurately calculate HA's characteristics.

HA is a naturally-occurring polymer that is present throughout all mammalian systems; it is of enormous commercial interest for ophthalmic, medical, pharmacological and cosmetic applications.

HA has been studied extensively using techniques such as size-exclusion chromatography and, more recently, single-capillary viscometry. However, SCV is vulnerable to noise generated by system pressure fluctuations, meaning even slight changes in flow rate can lead to vastly increased baseline noise which lowers the signal-to-noise ratio and produces lower experimental accuracy.

Wyatt has enabled scientists to explore the characteristics of HA by combining its instrument collection with SEC, to overcome the problems and produce a high S:N. In this application seven separate HA samples were used. Sample root sources varied and included HA from rooster comb, umbilical cord and bacterial fermentation.

The Optilab rEX was used for concentration measurements and, combined with the ViscoStar, allows for direct calculations of sample intrinsic viscosity. This refractive index detector is claimed to have 256 times the detection power and up to 50 times the dynamic range of any other RI detector. The rEX also allows measurement of the absolute refractive index of a solution.

Experimental collection and data analysis were performed with the Astra V software package. Using this enabled the collection and subsequent analysis of all 18 MALS angles. The software also uses a proprietary band broadening correction algorithm, which solves the problem of inter-detector band broadening, ensuring the accuracy of results.

Using the Dawn EOS allowed calculation of the absolute molar mass without the need for reference standards, column calibration or 'fudge factors'. Dawn light-scattering instruments incorporate multiple-angle detection to characterise directly and in real time and work with absolute precision, meaning that there is no need to refer to standards or assumptions a priori.