Fluorescence detection of protein content in house dust: the possible role of keratin

Abstract

We propose a fluorescence method for protein content assessment in fine house dust, which can be used as an indicator of the hygienic state of occupied rooms. The results of the measurements performed with 30 house dust samples, including ultrafiltration experiments, strongly suggest that the fluorescence emission of house dust extracts excited at 350 nm is mainly due to protein fragments, which are presumably keratin hydrolysates. This suggestion is supported by several facts: (i) Spectral band shapes for all the samples under investigation are close and correspond to that of keratin; (ii) fluorescence intensity correlates with the total protein content as provided by Lowry assay; (iii) treatment of the samples with proteinase K, which induces keratin hydrolysis, results in fluorescence enhancement without changing fluorescence band shape; and (iv) Raman spectra of keratin and fine house dust samples exhibit a very similar structure. Based on the obtained results and literature data, we propose a hypothesis that keratin is a major substrate for fluorescence species in fine house dust, which are responsible for emission at 350-nm excitation.

Melanin distribution from the dermal–epidermal junction to the stratum corneum: non-invasive in vivo assessment by fluorescence and Raman microspectroscopy

“…While all of that methods are suitable for imaging of melanin in the basal layer, as well as for quantification of bulk melanin concentration, for the upper layers of the epidermis data interpretation is not that straightforward. That is, direct attributing of fluorescence in the upper epidermis to melanin is not possible, as other fluorophores such as keratin 66 and proteins and/or lipids oxidation products 67 may also contribute to the emission signal. www.nature.com/scientificreports/ It should further be noted that the fluorescence intensity is prone to photobleaching, effectively reducing the fluorescence intensity over time.…”

Keratin-water-NMF interaction as a three layer model in the human stratum corneum using in vivo confocal Raman microscopy

“…Keratin is one of the abundant proteins found in the mammalian epidermis. Corneocytes of the stratum corneum (SC), the horny cells of human epidermis, are continuously proliferating from the stratum granulosum (SG) towards the skin surface 1 , 2 , contain a lot of the fibrous keratin 3 which is embedded in a water-lipid matrix 4 , and is almost homogenously distributed throughout the SC of healthy skin 5 . However, this can be different in the diseased skin 6 .…”

Carbon nanowalls as a platform for biological SERS studies

“…Hence, to verify the potential of CNW@Au substrates for biomedical applications we studied SERS-activity for biological macromolecules, whose electronic absorption values located far from Au plasmonic resonance excitation. Four types of molecules were used for testing of the prepared substrates: amino acid Tryptophan, nucleobase guanine, globular protein BSA and hydrolysates of keratin, the major protein of the outer layer of skin 18 . These molecules differ by size and molecular weight, while their absorption properties are rather similar - all the molecules demonstrate electronic absorption in the 250–280 nm range.…”

“…Isopropanol solution of tryptophan was prepared of 99% Sigma-Aldrich L-Tryptophan (Product number T8941). Keratin water solution was prepared from a human nail as it was described in 18 . To apply the solutions to the substrate, the 50 μ l Discovery micropipette was used.10 μ l of solution was applied to all substrates.…”