Hetero-Ligand peptide functionalization of gold nanoparticles for selective detection of cobalt (II) ions
Cobalt (II) ions, Co2+ represents one of the heavy metals that poses contamination to the environment. Despite being an essential element, over exposure to Co2+ can be detrimental to human health. To combat Co2+ contamination, monitoring the level of Co2+ with a fast detection technique is of ut...
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Format: | Thesis |
Language: | English English |
Published: |
2022
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Subjects: | |
Online Access: | http://psasir.upm.edu.my/id/eprint/113023/1/113023.pdf |
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Summary: | Cobalt (II) ions, Co2+ represents one of the heavy metals that poses
contamination to the environment. Despite being an essential element, over
exposure to Co2+ can be detrimental to human health. To combat Co2+
contamination, monitoring the level of Co2+ with a fast detection technique is of
utmost importance. Current techniques for Co2+ detection such as inductively
coupled plasma spectroscopy, atomic absorption spectrometry and voltammetry
are sophisticated, expensive, and laboratory bound. Thus, to overcome this,
nanomaterials was often used as probe for the development of colorimetric
detection approach due to its simplicity, rapidity, and effectiveness. This
research focusses on exploiting the gold nanoparticles (AuNPs) with unique
plasmon surface property. The approach involves functionalizing the AuNPs with
hetero-ligand peptide owing to its excellent capability for metal ion detection.
Herein, the successful functionalization of AuNPs were achieved with the
integration of a mono- (GCH-AuNPs and HCH-AuNPs respectively) and heteroligand
peptide (GCH+HCH-AuNPs). Both peptide ligands were synthesized
using solid phase synthesis approach. As both surface ligands of AuNPs formed
complexes with Co2+, the synergistic effect of hetero-ligand peptide exhibits
excellent colorimetric sensing performances where the sensor produced a color
change from red to blue could be observed by the naked eye and UV–visual
spectroscopy. There is a shift from 530nm (red) to 660nm (blue) which arises
from aggregation effect of the AuNPs. The colorimetric sensing using heteroligand
was selective towards Co2+ at as low as 100 ppb level. The colorimetric
sensing towards Co2+ also achieved a linear detection range from 100-1000 ppb
(R2 =0.9433) with detection limit was calculated to be at 300 ppb level. The
characterization and comparison of the mono-ligand and hetero-ligand system
was also supported by the analysis of dynamic light scattering and transmission
electron microscope to determine the changes in size of 20 nm AuNPs when
exposed to Co2+. This study have demonstrated a great potential of exploiting
mixed ligand peptide on nanomaterials in improving the performance of
colorimetric sensor of metal ions with high selectivity and sensitivity. |
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