Impact of luminescent MoSe₂ quantum dots on activity of trypsin under different pH environment

It is vital that a straightforward detection approach for trypsin should be developed as it is important diagnostic tool for a number of diseases. Herein, the impact of luminescent MoSe₂ quantum dots on trypsin activity under different pH environment has been studied. Addition of trypsin to MoSe₂ quantum dots enhanced the fluorescence of quantum dots whereas quantum dots resulted in quenching of fluorescence of trypsin. The quenching behavior at various pH and temperature was examined and revealed that the MoSe₂-trypsin complex stabilized through the electrostatic interactions. The obtained negative values of zeta potential of the complex -0.11 mV, -0.30 mV and -0.59 mV for pH 6.0,7.6 and 9.0 respectively confirmed the stability of the complex. The separation between the donor and acceptor atoms in energy transfer mechanism was found to decrease (1.48 nm to 1.44 nm to 1.30 nm) with increasing value of pH. It was also evident that trypsin retained its enzyme activity in the trypsin-MoSe₂ complex and under different pH environment. The Vant Hoff plot from quenching revealed 1 binding site for quantum dots by trypsin for all pH of buffer solution. The complex formation of trypsin-MoSe₂ quantum dots was verified for the first time using fluorescence spectroscopy and it revealed that tryspin form complex with MoSe₂ quantum dots through electrostatic interactions. Our results revealed that the MoSe₂ quantum dots stabilized and sheltered the active sites of trypsin, which was likely the cause of the increased bioavailability of MoSe₂ quantum dots in enzymes.