Developing point-of-need (PON) cancer biosensors using microfluidic paper-based analytical devices: recent advances

Microfluidic paper-based analytical devices (µPADs) are considered a key solution as they offer a low-cost platform for developing point-of-need (PON) biosensors for cancer biomarker/cell detection. Nanomaterials utilized in the structures of µPADs and PADs provide powerful tools for the early-stage diagnosis of cancer. This review aims to summarize the recent advances in a variety of µPADs and PADs used for cancer diagnosis based on different types of nanomaterials, such as metal/metal oxide nanoparticles, magnetic nanoparticles, quantum dots, and 1-3 dimensional materials. This review also discusses the properties and functions of various nanomaterials, highlighting their recent applications in PAD- and µPAD-based diagnosis of cancer biomarkers and cells based on immune-, apta-, geno-, peptide-, and enzymatic-biosensing. Additionally, the critical role of detection techniques, like electrochemical, optical (UV-Vis spectrophotometry, SPR, SERS, and fluorometry), electrochemiluminescent, photoelectrochemical, and piezoelectric methods, in label-free and labeled bio-assays of cancer biomarkers are surveyed. The advantages and limitations of various sensing methods, techniques, types of materials and fabrication strategies are surveyed to explore the best cases for cancer diagnosis using PADs and µPADs. The roles of novel technologies such as AI and IOT, in the development of PAD- and µPAD-based cancer diagnosis are investigated. Finally, a comparison of the advantages and limitations of PADs and µPADs in the early-stage diagnosis of various cancers is reviewed towards exploring the research/technological gaps.