Nanoparticle Assay Amplification via Isothermal RPA

The patent applies preliminary action by performing isothermal amplification of the target nucleic acid before the nanoparticle detection step. The amplification compartment pre-enriches the target analyte using recombinase polymerase amplification (RPA), which increases the concentration of low-abundance targets to levels detectable by the nanoparticle system. This preliminary enrichment step resolves the sensitivity limitation without requiring complex instrumentation beyond the portable device.

The patent uses an intermediary approach by introducing amplified nucleic acid as a mediator between the sample and the nanoparticle detection system. The RPA amplification process generates multiple copies of the target sequence, which then serves as the input for the nanoparticle-based detection. This intermediary amplification step bridges the gap between low-abundance targets and the detection threshold of the nanoparticle system.

The patent applies parameter changes by transitioning from thermal cycling (PCR) to isothermal conditions (RPA). Instead of requiring temperature cycling between denaturation, annealing, and extension phases, the RPA reaction proceeds at a constant temperature (typically 37-42°C), eliminating the need for expensive thermal cyclers. This parameter change from variable temperature to constant temperature maintains amplification capability while dramatically simplifying the equipment requirements for point-of-care use.

The patent substitutes the mechanical thermal cycler system with a simpler isothermal reaction system. The complex mechanical temperature cycling mechanism is replaced by a straightforward isothermal incubation process that can be maintained by simple heating elements or even body temperature, making the system suitable for resource-limited settings without trained technicians.

The patent merges the DNA extraction and amplification processes into a single integrated workflow. The lysis buffer and RPA reagents are combined in the same compartment, allowing direct amplification of nucleic acid released from lysed cells without requiring separate extraction, purification, and resuspension steps. This merging of extraction and amplification functions dramatically reduces processing time and operational complexity while maintaining reliable DNA recovery.

The patent extracts only the essential function of DNA extraction—nucleic acid release—by using a lysis buffer that directly releases DNA from cells in the sample. Rather than performing complete purification protocols, the system extracts sufficient nucleic acid for amplification directly from the lysate, eliminating time-consuming purification steps while maintaining enough reliability for downstream detection.

The patent applies universality by designing a multi-functional integrated chip that performs lysis, amplification, and detection in a single device. The chip contains multiple compartments that can be sequentially filled with sample and reagents, and the entire process is driven by passive capillary flow or simple pumping, enabling automation without complex mechanical manipulation. This universal platform handles multiple diagnostic functions within a single automated system.

The patent implements self-service through passive fluid handling mechanisms where capillary action or pressure gradients automatically move samples and reagents through the chip compartments without requiring active pumping or complex automation. The system serves itself by using the properties of the fluids and chip structure to drive the process, minimizing the need for external automation infrastructure.