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- Ratiometric optical visual immunosensor based on quantum dots for CA 19-9 protein detectionPublication . Oliveira, Daniela; Piloto, Ana Margarida L.Cancer is a global health challenge, where early detection is crucial to increasing survival rates. Non-invasive, rapid, and affordable diagnostic methods are urgently needed. Immunosensors emerge as promising alternatives to traditional methods such as ELISA, allowing point-of-care (PoC) analyses. This study aims to develop a highly sensitive and selective optical immunosensor for detecting CA 19-9. The results demonstrate successful detection of CA 19-9 over a wide concentration range from 1.77 to 501.87 U mL-1 in 1000-fold diluted human serum in just 10 minutes, with high precision. This device offers rapid, sensitive, and affordable detection, making it suitable for clinical PoC applications.
- Electrochemical miRNA-34a-based biosensor for the diagnosis of Alzheimer’s diseasePublication . Pereira, Raquel L.; Oliveira, Daniela; Pêgo, Ana P.; Santos, Sofia D.; Moreira, Felismina T.C.Alzheimer's disease (AD) is the most common dementia type and a leading cause of death and disability in the elderly. Diagnosis is expensive and invasive, urging the development of new, affordable, and less invasive diagnostic tools. The identification of changes in the expression of non-coding RNAs prompts the development of diagnostic tools to detect disease-specific blood biomarkers. Building on this idea, this work reports a novel electrochemical microRNA (miRNA) biosensor for the diagnosis of AD, based on carbon screen-printed electrodes (C-SPEs) modified with two gold nanostructures and a complementary anti-miR-34a oligonucleotide probe. This biosensor showed good target affinity, reflected on a 100 pM to 1 μM linearity range and a limit of detection (LOD) of 39 pM in buffer and 94 aM in serum. Moreover, the biosensor’s response was not affected by serum compounds, indicating selectivity for miR-34a. The biosensor also detected miR-34a in the cell culture medium of a common AD model, stimulated with a neurotoxin to increase miR-34a secretion. Overall, the proposed biosensor makes a solid case for the introduction of a novel, inexpensive, and minimally invasive tool for the early diagnosis of AD, based on the detection of a circulating miRNA overexpressed in this pathology.