Lab-in-a-syringe using gold nanoparticles
In addition to their low sensitivity, two major limitations of LFAs are related to the requirement of samples poured directly onto the (exposed) sample pad, which can be dangerous, especially for handling of hazardous samples, and to the fact that they can only handle small volumes (typically 200 microliters) of sample per analysis. Given the aforementioned context, we propose a new, paper and gold nanoparticle-based lab-in-a-syringe (LIS) device. It employs a simple vertical-flow immunoassay (VFIA) that operates simultaneously to sampling. By inserting the conjugate pad and detection pad inside plastic cartridges that can be connected to a syringe, we are able to minimize handling of the sample by the operator and expand the volume of sample that can be analyzed (up to 5 mililiters), thereby making the device safer and more sensitive than similar tools (Figure 4). Like most other paper-based diagnostic devices, our new LIS is easy to use and fast, providing a read out in less than 10 minutes. We demonstrate its applicability for the detection of PSA in real human urine samples at clinically relevant concentrations. Beyond this clinical proof-of-concept application, our LIS has enormous potential for applications in fields such as food control, safety and security, and environmental analysis. [5]