Quantitative immunoassays of matrix Metalloproteinase-9 in tears using a contact Lens

Matrix metalloproteinase-9 (MMP-9) in tears is used as a biomarker for dry eye disease (DED), biomarkers for other ocular surface disorders (OSD) and for systemic diseases. Almost all biomarkers found in blood are also known to be present in tear fluid. Sample collections from tears are difficult due to the small available volumes and the rapid change in tear composition upon physical contact. Silicon hydrogel (SiHG) contact lenses provide an opportunity to create sensors without embedded electronic components. SiHG contact lenses provide rapid transport of ions and oxygen to support the corneal cells. These features provide patient comfort and long wear times up to one month. SiHG lenses are currently the most widely used and prescribed lenses because of patient satisfaction. The SiHG contact lenses (CL) have a unique chemical composition and 3D topology which makes them well suited for bioassays using the lenses. The SiHG lenses were modified to provide a capture immunoassay for MMP-9. The assay was accurate over a range of MMP-9 concentrations in tears over 30 ng/mL from individuals with DED. The assay design can be readily modified to obtain sensitivity of 4 ng/mL for individuals without DED and provide the physician with actual MMP-9 concentrations over the entire range of clinical concentrations. Capture Ab binding to the CL is based on poly-l-lysine (PL) and can be used with almost any Ab or protein. Hence, this approach can be used to detect additional OSDs or systemic diseases biomarkers on the same contact lens. Contact lenses for other biomarkers can be made using the same procedures discussed in this report and also provides the opportunity detection of multiple biomarkers using a single SiHG contact lens.