A Lightweight Paper Sensor for Real-Time Detection of Human Serum Albumin Based on Imaging and Spectroscopy Methods

Detecting albumin levels quantitatively is challenging due to interference from other substances and lengthy reaction times. In this research, we proposed a lightweight paper sensor for real-time human serum albumin (HSA) detection, utilizing imaging and spectroscopy techniques. By combining bromocresol green (BCG) with HSA, we induced a structural change in BCG, resulting in protonation from
$\text{C}_{{21}}\text{H}_{{14}}$
Br4O5S to
$\text{C}_{{21}}\text{H}_{{12}} \mathrm{Br}_4 \mathrm{O}_5^{2-} \mathrm{S}$
, leading to a blue–green coloration. Subsequently, we applied this reagent to test paper for the reaction, utilized a smartphone camera for image detection, and performed spectrophotometric analyses. Our study presents a convenient, swift, and quantitative approach to measuring HSA concentration, initially accessible through a smartphone camera. In addition, spectrophotometric analysis ensures precise quantification.