21ENGBIO-THE TRANSDUCING ANALYTICAL BIOSYSTEM (TABS): A PLATFORM FOR DIAGNOSTICS (TABS-DX)

The world market for biosensors was $42Bn before Covid and is expected to double in the next 6yrs, still dominated by clinical diagnostics and disease management, demanding new technologies for early detection at lower cost. Covid-19 testing made in vitro diagnostics (IVDs) a household product, but IVDs are not only expected to play their part in faster identification of causative pathogens and containment of infectious disease, but there is also a need in treatment and management in acute and chronic disease, enabling earlier diagnosis with appropriate treatment, improving patient outcomes. There is interest from neonatal and paediatric units in Cystatin C (CysC) as a marker of acute renal function, as well as a predictor of morbidity and mortality. It is a much earlier indicator than the normally used creatinine and is particularly attractive for assessing kidney function in paediatrics/neonatology and intensive care, where acute fluctuations in glomerular filtration rate GFR and lack of creatinine sensitivity to incipient renal impairment puts children at risk from antibiotic toxicity.

Many bioanalytical reagents for medical diagnostics are enzymes, antibodies, peptides etc. They are derived from nature and mostly produced by fermentation techniques. However, they aren't intrinsically smart materials; ie they don't usually yield an analytical signal that can be measured without further (chemical) modification of the bioanalytical reagent or addition of chemical indicators. The additional manufacturing costs and chemical reagents adds significant cost and reduces the 'green' impact of the manufacturing by fermentation. It also means that small volume biomarker measurement targets do not become commercially viable. It needs 'blockbuster' targets like glucose monitoring for diabetics to be an attractive commercial investment.
In this project we will use synthetic biology to make smart analytical reagents: the TRANSDUCING ANALYTICAL BIOSYSTEM (TABS) as a platform for diagnostics (TABS-DX). The TABS can be attached to fibres and particles, making them easier to use and to store. A CysC point of care test system will be designed and a novel vacuum printing technique will be trialed to deposit the fibres or particles to produce prototype in vitro diagnostics for CysC, which will be tested in a clinical study, with the paediatrics unit.

Immunological-based assays for protein biomarkers that correlate with disease status are essential for clinical diagnosis. Compared to traditional polyclonal and hybridoma-made monoclonal antibodies, scFvs provide significant practical advantages. These include rapid in vitro antigen screening and ease of large-scale manufacturing based on simple and economical E coli-based expression systems. In addition, the affinity, stability and specificity of candidate scFvs can be improved or manipulated using mutagenesis/selection approaches. Importantly, additional protein markers/enzymes can be bioengineered onto the scFv backbone to generate the suitable reagents for a wide variety of immunoassay formats. Our strategy will be to combine appropriate scFvs with a wide variety of 'modular' additions chosen for specific analytical and/or experimental needs. The modules can be easily incorporated into the scFv structure by standard recombinant DNA techniques. All of these features, combined together should facilitate an approach that emphasises rapid, low-cost applications. Major benefits will therefore be to overcome a noted bottleneck in the development of analytical in vitro diagnostics. The technology is eminently transferable to local industrial production in third world setting.