title: Development of an Indicator Displacement Based Detection of Malaria Targeting HRP-II as Biomarker for Application in Point-of-Care Settings.
abstract: A novel label free spectrophotometric detection of malarial biomarker HRP-II following an indicator displacement assay has been developed. The assay is based on competitive displacement of murexide dye from its complex with Ni2+by HRP-II present in serum samples. The binding constant (Kd) discerned for the dye and HRP-II to Ni2+were 1.4 × 10-6M-1and 6.8 × 10-9M-1, respectively. The progress of the reaction could be monitored from the change of color from orange (∼λ482 nm) to pink (∼λ515 nm) with the concomitant increase in HRP-II concentration in the mixture. A linear response (R2= 0.995) curve was generated by plotting the ratio of absorbance (λ515 nm/λ482 nm) against the HRP-II concentrations. The method offers to detect HRP-II as low as 1 pM without any interference from some common salts and the major protein, HSA, present in the blood serum. The detection method was reproduced in a microfluidic paper based analytical device (μPAD), fabricated by printing hydrophobic alkyl ketene dimer on a chromatographic paper to create hydrophilic microchannels, test zone, and sample application zone. The device offers to use a maximum sample volume of 20 ± 0.06 μL and detects HRP-II within 5 min with LOD of 30 ± 9.6 nM in a dynamic range of 10 to 100 nM. The method has thus immense potential to develop as rapid, selective, simple, portable, and inexpensive malarial diagnostic device for point-of-care and low resource setting applications.
authors.affiliation: Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati , Guwahati, Assam 781039, India.
authors.forename: Babina
authors.initials: B
authors.lastname: Chakma
authors.affiliation: Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati , Guwahati, Assam 781039, India.
authors.forename: Priyamvada
authors.initials: P
authors.lastname: Jain
authors.affiliation: Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati , Guwahati, Assam 781039, India.
authors.forename: Naveen K
authors.initials: NK
authors.lastname: Singh
authors.affiliation: Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati , Guwahati, Assam 781039, India.
authors.forename: Pranab
authors.initials: P
authors.lastname: Goswami
mesh_terms: D000953:Antigens, Protozoan / Q000097:blood*; D015415:Biomarkers / Q000097:blood*; D056831:Coordination Complexes / Q000737:chemistry; D006801:Humans; D008288:Malaria / Q000175:diagnosis*; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation / Q000379:methods*; D009532:Nickel / Q000737:chemistry; D010209:Paper; D019095:Point-of-Care Systems; D016062:Porosity; D015800:Protozoan Proteins / Q000097:blood*; D013053:Spectrophotometry
chemical_list: D000953:Antigens, Protozoan; D015415:Biomarkers; D056831:Coordination Complexes; C514457:HRP-2 antigen, Plasmodium falciparum; D015800:Protozoan Proteins; D009532:Nickel