Biological Contamination of Nanoparticles and Its Manifestation in Optical Absorbance Measurements.

The biological contamination of nanomaterials is a serious problem hampering their widespread use in biomedical products. Existing commercial chromogenic assays for the detection and quantification of biocontaminants such as endotoxin can interfere with nanoparticles thus leading to unreliable data. The results reported in this Letter offer a solution to the aforementioned problems of the nanoparticle interference and correct quantification of biocontaminants by decomposing their optical absorbance into two physically measurable components and analyzing them as a function of the concentration of contaminated nanoparticles.