Biomolecule analysis using portable absorption spectrophotometer with novel spatial filter

Biomolecules reflect the onset and progression of disease as well as overall health status, rendering their quantification essential. Although various techniques exist for biomolecule quantification, colorimetric analysis is widely used owing to its simplicity and rapid results. However, conventional absorption spectrophotometers used in such analyses suffer from measurement errors caused by stray light, such as reflected and scattered light, which compromise accuracy. This study introduces a portable absorption spectrophotometer with a novel spatial filter featuring a light-guiding structure designed to suppress stray light. This innovation enables rapid and highly sensitive quantification of biomolecules in the field. Using the proposed device, biomolecular samples including proteins and amino acids were analyzed. The results demonstrated a high linearity in the calibration curve ( R 2 > 0.99), confirming a reliable correlation between absorbance and concentration. Real protein samples, such as serum and immune cells, were quantified with accuracies comparable to those of commercial spectrophotometers, further validating the applicability of the device. These findings highlight the device's potential as an effective tool for biomolecule evaluation in various environments, offering portability, sensitivity, and reliability. • A portable yet accurate absorption spectrophotometer was developed. • A spatial filter with a light-guiding structure is used to suppress stray light. • The achieved accuracies are comparable to those of commercial spectrophotometers. • The developed device enables reliable biomolecule evaluation in the field.