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Label-Free, Direct Measurement of Protein Concentrations in Turbid Solutions with a UV–Visible Integrating Cavity Absorbance Spectrometer
- Larson, Nicholas R., Wei, Yangjie, Middaugh, C. Russell
- Analytical chemistry 2018 v.90 no.8 pp. 4982-4986
- absorbance, biotechnology, microparticles, nanogold, proteins, spectrometers, staining
- Protein–particle conjugates and mixtures have been investigated extensively for their diverse applications in biotechnology. However, general methods to measure protein concentration of protein–particle solutions are lacking. Typically, proteins in turbid solutions require separation or staining with another chromophore to quantitate their concentration. Here we demonstrate a label-free, direct approach to measure protein concentrations in turbid solutions using a UV–vis integrating cavity absorbance spectrometer. Three systems are used to test the ability to measure accurate protein concentrations: proteins adsorbed to Alhydrogel, proteins in solution with gold nanoparticles, and proteins encapsulated within polymeric microspheres. Protein concentrations in each of the three protein–particle systems were successfully quantified using a calibration curve created from the absorbance at 280 nm.