complexes because of the various reasons; First, high rate of adsorption of the
protein on it. Second, chemistries that make the membrane wettable with aqueous
solution which helps in protein adsorption. Third, the pore size of membrane can be
controlled according to requirement. The general detection steps of paper assay is
depicted in Fig.2.20.
In the past decade, lateral flow or paper based assay have been widely used in
various types of biologically relevant applications including paper-based molecular
assays, paper-based ELISA (P-ELISA), paper-based nucleic acid assays, and paper-
based cell assays for rapid diagnostic of protozoan and viral diseases like malaria,
dengue etc. [ 57 ]. Compare to other existing detection techniques, the Paper based
rapid diagnostic kits (RDT) require little or no pre sample preparation and give
results in few minutes. Guidelines for the evaluation of malaria diagnostic assays
have been published and provide a standardized approach to diagnostic assessment
[ 67 ]. In recent years various researchers has performed testing of Plasmodium
falciparum on paper based device. Pereira et al. [ 68 ] fabricated the 3-D paper
based device to detect malaria biomarker in a single step. The concentration and
detection steps were integrated into single step that occurs entirely within a portable
paper-based diagnostic strip. Figure2.21shows the schematic device for malaria
detection on a single chip.
Weaver et al. [ 69 ] performed chemical colour tests embedded on a paper card
which can significantly identify formulations corresponding to very low quality
anti-malarial drugs. The presence or absence of chloroquine (CQ), doxycycline
(DOX), quinine, sulfadoxine, pyrimethamine, and primaquine antimalarial medi-
cations, were examined. The sensitivity of the developed test card varies from 90 to
100 % with no false positives in the absence of pharmaceutical. For detection of
extremely low concentrations of parasite target, a combined system has been
developed which combines the isothermal amplification (Recombinase Polymerase
Fig. 2.20The schematic diagram of paper based colorimetric detection assay. (1) Sample pad:
blood sample with viral proteins pipetted onto it; (2) filter paper: through which blood is migrated
towards conjugated pad; (3) conjugated pad: conjugated antibody-nano nanoparticles pipetted
onto it; (4) nitrocellulose membrane (5) test line: visualization of color change if there is any
positive test result. (6) Control area (7) absorbent pad: to wick the extra fluid
58 G. Bhatt et al.