Amino benzene dicarboxylic acid-derived luminescent nitrogen-doped Carbon- quantum Dots/anti-TNT antibodies conjugate for detection of nitroaromatic contaminant in water: A comparative analysis of chemo-Bio-sensing affinity

Abstract

Water contaminants are posing deadly impacts on living beings' survival. Nitroaromatic compounds e.g. Trinitrotoluene (TNT), are one among these lethal contaminants and require to be early detected before their consumption. The nitrogen-doped carbon quantum dots (NCQDs) are synthesized from the precursor 2-aminobenzene-1,4-dicarboxylic acid via the hydrothermal route. The as-synthesized NCQDs are conjugated with anti-TNT antibodies and characterized using various analytical techniques. The spherical NCQDs are having a size of 5.69 nm. At excitation wavelength 347 nm, the emission wavelength of NCQDs is shifted from 445 nm to 443 nm after their conjugation with anti-TNT Ab. The decrease in photoluminescence emission intensity of NCQDs and NCQDs/Ab with the increased concentration of TNT is regulated by the formation of Jackson-Meisenheimer and antigen–antibody complex, respectively. The detection limit of NCQDs and NCQDs/Ab is observed to be 1.39 X 10-5 M and 1.07 X 10-9 M respectively. The stern–volmer quenching constant of NCQDs is increased from 1.5 X 103 M−1 to 8.5 X 105 M−1 after their conjugation with anti-TNT Ab depicting the elevated affinity of NCQDS/Ab for TNT. The biosensing NCQDs/Ab are found to be more selective towards TNT than the chemosensing NCQDs probe. In spiked real water samples, the RSD of NCQDs/Ab is found to be ± 1.5%.