HA is a naturally-occurring polymer that is present throughout all mammalian systems, and of 'enormous' commercial interest for ophthalmic, medical, pharmacological and cosmetic applications
Wyatt Technology has combined its innovative instruments to explore the material characteristics of the biopolymer hyaluronic acid (HA).
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, says Wyatt.
HA has been studied extensively using techniques such as size-exclusion chromatography (SEC) and, more recently, single-capillary viscometry (SCV).
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 (S:N) and thus produces lower experimental accuracy.
Wyatt Technology has enabled scientists to reliably explore the material characteristics of HA by combining its innovative instrument collection with SEC, to overcome such problems and produce an extremely 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.
Wyatt's ViscoStar, described as a new generation online differential viscometer which incorporates a traditional four-arm bridge design, was used to directly determine the sample specific viscosity.
The bridge design is inherently insensitive to pressure fluctuations and is thus able to tolerate pump pulses.
The ViscoStar is also the only viscometer that can measure intrinsic viscosity across the peaks of monodisperse samples, providing truly accurate readings for the first time, claims Wyatt.
In this instance, the combination of bridge design, precise thermal control and contemporary electronics results in a device which produces outstanding S:N.
The Optilab rEX from Wyatt was used for concentration measurements and, combined with the ViscoStar, allows for the direct calculations of sample intrinsic viscosity.
This refractive index (RI) detector is said to have 256 times the detection power and up to 50 times the dynamic range of any other RI detector in existence.
The Optilab rEX also allows measurement of the absolute refractive index of a solution; this is said to be a unique option not possible with any other on-line RI detectors.
Experimental collection and data analysis were performed with Wyatt's Astra V software package.
Using Astra V enabled the collection and subsequent analysis of all 18 Mals angles.
The Astra software also utilises a proprietary band broadening correction algorithm, which solves the persistent 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.
Wyatt says the results of the application demonstrate that the utilisation its ViscoStar, Dawn EOS and Optilab rEX in tandem with its Astra software, giving unprecedented rapid, accurate analysis.
Results determined the absolute HA molecular weight, molecular weight distribution and radii information to be consistent with historical literature values.
