AbstractA novel fiber optic probe was developed and used to investigate the mass transport of proteins through a polyacrylamide matrix. The basic component of the probe was an optical fiber, employing the evanescent wave as an excitation source for molecules near its surface. The optical fiber was coated with a very thin film of polyacrylamide, and the rate of diffusion through this matrix for proteins tagged with FITC (fluorescein isothiocyanate) was determined. The diffusivity of FITC‐β‐galactosidase was 1.6 × 10−10cm2/sec. A bimodal distribution in size was observed in the albumin sample, with the diffusivities of the two components differing by an order of magnitude (D1= 4.9 × 10−10cm2/sec, D2= 3.5 × 10−10cm2/sec). Studies were also performed to determine the effect of crosslinking the matrix on the mass transfer of FITC‐albumin. The diffusion coefficient was reduced as the time of exposure to the crosslinking solution (triethylene diamine) increased. After twenty minutes of exposure to the crosslinking solution, the larger of the two albumin species was excluded from the matrix and only one diffusing speci
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