Studies on l-histidine capped Ag and Au nanoparticles for dopamine detection

- L-His functionalized Ag, Au and bimetallic Ag-Au nanoparticles were prepared and its properties were studied.
- L-His based Ag, Au, Ag-Au nanoparticles have characterized by spectroscopy, XRD and microscopic studies.
- Enhanced optical nature of nanoparticles delivers the best platform to develop a biosensor for DA detection.
- For qualitative determination of dopamine, SPR of metal nanoparticles plays a major role in dopamine determination.
- This basic finding can be utilized for further identification of imbalanced DA concentration in body fluids.

This work demonstrates the effective surface functionalization of Ag, Au and bimetallic Ag-Au nanoparticles using l-histidine for colorimetric detection of dopamine (DA) which plays majorly in recognizing the neurological disorder. l-Histidine (l-His) capped Ag, Au, and bimetallic Ag-Au nanoparticles are characterized using physico-chemical techniques. The optical behaviour of nanoparticles has been analysed at various time intervals using UV-Vis absorption spectroscopy. FT-IR results provide the evidence of chemical bonding between l-histidine and metal nanoparticles. Its structure with the capping of l-His was clearly shown in HR-TEM images. The average size of nanoparticles has calculated from TEM image fringes are 11 nm, 5 nm and 6.5 nm respectively, matches with crystals size calculated from X-ray diffraction pattern. Enhanced optical nature of nanoparticles provides the best platform to develop a colorimetric-based biosensor for DA detection. After addition of DA, a rapid colour change has been noted in colloids of nanoparticles. The substantial changes in absorbance and λmax in metal nanoparticles respect to DA concentration have been observed and formulated. This is one of the successive methods for trace level determination of DA and will be going to a significant material for designing biosensor to determine DA in real extracellular body fluids.

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