Wash-free operation of smartphone-integrated optical immunosensor using retroreflective microparticles

Smartphone-Based Multiplexed Biosensing Tools for Health Monitoring

“…Integrating optical sensors into smartphones has become popular in recent years due to the practical image analysis provided by smartphones [ 38 , 39 , 40 , 41 ]. Smartphone applications, such as FLASK station and ImageJ, are often used for data analysis [ 42 , 43 ]. In 2021, Zhang et al designed a portable, optical, smartphone-based quantum barcode imaging platform that can diagnose in real time the severe acute respiratory syndrome virus (SARS-CoV-2) at different levels of infectious severity with 90% sensitivity and 100% specificity [ 44 ].…”

Progress in the Optical Sensing of Cardiac Biomarkers

“…Retroreflection is an optical phenomenon that consists in the reflection of the incident light back to the light source by a specific surface called a “retroreflector”. This optical phenomenon, widely exploited to make traffic signs and reflective tape for clothing, was considered recently for signal transduction in the field of biosensors [ 111 , 114 , 115 ]. The use of polychromatic instead of monochromatic light reduces the cost of optical detection, while the compatibility with the smartphone LED flash and camera is an additional huge asset of retroreflection devices.…”

Recent Developments in the Field of Optical Immunosensors Focusing on a Label-Free, White Light Reflectance Spectroscopy-Based Immunosensing Platform

“…Novel immunosensors based on optical waveguide light mode spectroscopy (OWLS) were developed and applied to the detection of Fusarium mycotoxin zearalenone; both immobilized antibody and immobilized antigen assay formats were set up, with the immunoreagents’ immobilization being performed on epoxy-, amino-, or carboxy-functionalized sensing surfaces [ 79 ]. A micro-sized non-spectroscopic optical reflector gadget was fabricated that was based on anti-analyte antibodies conjugated to retroreflective particles; the gadget was integrated with a commercial smartphone and applied to the detection of the creatine kinase-myocardial band [ 80 ]. Moreover, a Fabry-Pérot interferometric surface stress sensor was developed and applied to detection of prostate-specific antigen (PSA); the sensor employed anti-analyte antibodies covalently immobilized on a deformable biomembrane constructed on a parylene-C nanosheet support/silicon substrate, and the reflection spectra shifts created upon antibody-analyte binding due to membrane deformation were recorded [ 81 ].…”

“…Several optical immunosensors have been developed for the detection of whole bacteria, such as Staphylococcus aureus [ 68 ], especially methicillin-resistant Staphylococcus aureus [ 54 ], Salmonella typhi VI [ 59 ], Escherichia coli O157 [ 60 ], and Salmonella typhimurium [ 88 ]. Other optical immunosensors have been applied to and/or evaluated for the detection/quantification of specific disease biomarkers, such as neuron-specific enolase [ 56 ], myocardial creatine-kinase [ 80 ], prostate-specific antigen [ 81 ], human epididymis protein 4 [ 57 ], programmed death ligand 1 [ 73 ], cardiac troponin I [ 78 ], and C-reactive protein [ 87 ]. Another group includes optical immunosensors that have been applied to and/or evaluated through the detection/quantification of basic and important biomolecules, such as human INF-γ or insulin [ 62 ], immunoglobulin G [ 69 ], CD5 [ 76 ], collagen I [ 72 ], cortisol [ 74 ], and estrone and estradiol [ 63 ].…”