Simple colorimetric methods for determination of sub-milligram amounts of ultra-high molecular weight polyethylene wear particles

New colorimetric methods are described for determination of sub-milligram amounts of ultra-high molecular weight polyethylene (UHMWPE) wear particles. These methods are based on the irreversible binding of the fluorescein-conjugated bovine serum albumin or the hydrophobic dye Oil Red O to wear particles. UHMWPE particles bind both substances from their solutions and thus decrease the absorbance of these solutions. The decrease is linearly dependent on the amount of added wear particles in the sub-milligram range suitable for practical use. The newly developed method offers improved accuracy and precision compared to Fourier transformed infrared spectroscopy (Slouf M, et al. Quantification of UHMWPE wear in periprosthetic tissues of hip arthoplasty: description of a new method based on IR and comparison with radiographic appearance. Wear 2008;265:674-684.)