Magnetic Nanobead Paper-Based Biosensors for Colorimetric Detection of <i>Candida albicans</i>

<i>Candida albicans</i> (<i>C. albicans</i>) infections pose significant challenges in clinical settings due to their high morbidity and mortality rates in addition to their role in tumor progression. Current diagnostic methods, while effective, often suffer from limitations that hinder a timely intervention. Therefore, there is an urgent need for a simple, sensitive, specific, and low-cost colorimetric biosensor for the rapid detection of <i>C. albicans</i>. This new biosensing platform comprises a gold platform carrying a specific <i>C. albicans</i> peptide substrate conjugated with magnetic nanobeads. Hence, the sensing platform was black, and the operation was based on the proteolytic activity of <i>C. albicans</i>, offering a visual color change to yellow upon cleavage of the conjugated peptide substrates on the magnetic nanobeads. Specificity testing demonstrated the biosensor's ability to distinguish <i>C. albicans</i> from other <i>Candida</i> species and microorganisms, while stability testing confirmed its long-term performance. Clinical testing revealed the biosensor's high sensitivity in detecting <i>C. albicans</i> in both standard cultures and clinically isolated samples with a lower limit of detestation of 3.5 × 10³ CFU/mL. Although further validation against conventional and molecular methods is warranted, our colorimetric biosensor holds promise as a rapid (5 min) and cheap (Less than 2 $) point-of-care solution for the early detection of <i>C. albicans</i> infections, facilitating a timely intervention and improving patient outcomes in clinical practice.