Wax-on-plastic biosensor platform for point-of-care nucleic acid diagnostics

Overview

Wax-on-Plastic devices are low-cost, miniaturized diagnostic platforms fabricated by printing wax patterns on flexible plastic substrates using standard desktop printers. The chip surfaces are functionalized with biocompatible two-dimensional nanomaterials—molybdenum disulfide (MoS2) and graphene oxide—that selectively bind nucleic acids and generate measurable electrical signals. This combination enables sensitive, label-free detection of DNA and RNA targets without the need for fluorescent labels, complex optics, or extensive sample preparation. The technology is designed for point-of-care deployment, including in-field plant disease diagnostics, and can be configured in array format to screen multiple biomarkers in parallel from very small sample volumes.

Technical specifications

• Substrate and fabrication: Wax patterns are printed on flexible plastic sheets using desktop printers, eliminating the need for cleanroom facilities or microfabrication equipment.
• Transducer surfaces: MoS2 and graphene oxide coatings provide natural affinity for single-stranded DNA, RNA, and peptide nucleic acid (PNA) probes, enabling direct adsorption-based assays.
• Detection method: Label-free voltammetric readout using charge transfer properties at the nanomaterial–nucleic acid interface.
• Sensitivity benchmarks: Theoretical limit of detection down to 3 attomolar DNA concentration; demonstrated detection of approximately 300 target molecules on MoS2 surfaces and 18 DNA molecules in a 300 nanoliter sample on graphene oxide.
• Multiplexing capability: Array format with 8 sensing electrodes (1.2 mm diameter each) for parallel detection of multiple nucleic acid biomarkers.
• Selectivity: Probe-functionalized surfaces can discriminate single nucleotide polymorphisms and detect expanded DNA repeat lengths associated with disease states.
• Portability: Readout is compatible with portable potentiostats suitable for field and point-of-care use.

Technology readiness level

The platform has been validated in laboratory studies with label-free DNA and RNA assays on MoS2- and graphene oxide-modified wax-on-plastic chips, including multiplexed detection with PNA probes. Published peer-reviewed work supports the sensitivity, selectivity, and feasibility of the approach for nucleic acid biosensing. Ongoing and planned validation will extend the technology to plant pathogen detection using synthetic probes in plant fluids with minimal sample preparation, paired with portable potentiostat readout. The current stage is best described as late-stage laboratory validation (TRL 4–5), with field-ready deployment and plant-disease assay validation as the next milestones toward commercialization.