5. L-Cysteine (L-Cys) is one of the 20 amino acids commonly
found in natural proteins (nonessential amino acid)
Which is extensively used in the food industry as an
antioxidant and in the pharmaceutical industry as a
biomarker and plays an important role in several biological processes
In rare cases, cysteine may be essential for children, the elderly people with certain
metabolic diseases and malabsorption syndromes
Cysteine can usually be synthesized by the human body sufficient quantity of
methionine is available
WHO recommended normal level of cysteine present 15 µmol/L in human blood
4
6. Copper is an essential transition metal element for human health and serves as a
critical cofactor for many enzymes, Because it can undergo a redox-active
Cu(I)/Cu(II) conversion
However, copper is also highly toxic toward organisms when presented in excess
Because it may promote the generation of reactive oxygen species (ROS). ROS
interfere with cellular signaling, cause damage to cell structures
Gastric disorder, liver or kidney damage, may also be induced with high
concentration of Cu2+, additionally, copper accumulation in the neuronal cytoplasm
might cause Alzheimer’s, Parkinson’s diseases
The U.S.Environmental Protection Agency (EPA) limits the Cu2+ levels in drinking
water to 1.3 mg/L 5
7. 6
Size: 12-20 nm
SPR band
High Surface coverage
Metallic nature
Low cost and
Highly stable
AgNPs
Biomedical
Catalysis
Sensor
Environment
Electronics
Textiles
11. (A) UV-vis spectra of (a) Trehalose, (b) AgNO3, (c) Treholse + AgNO3 and (d) Th-AgNPs. (B) UV-vis spectrum of Th-
AgNPs. Inset: AgNPs
10
12. UV-vis spectra of (a) freshly prepared and (b) One week aged AgNPs. Inset: (i) and (ii), Photograph of
corresponding AgNPs.
11
13. 11
112
Effect of pH: (A) UV-vis spectra Th-AgNPs in the presence of phosphate buffer 3 to 12 (0.2 M), (B) pH vs
Absorbance diagram.
14. Effect of Time: (A) AgNPs in the presence of 1.66×10-07 M Cys [2 mins], (B) Cys-AgNPs in the presence of
8.17×10-07 M Cu2+ [1 mins] at different time Vs relative absorbance.
113
Cys Cu2+
16. UV-vis spectra of AgNPs in the presence of different concentration Cys (a) 0, (b) 1.67, (c) 3.32, (d) 4.98, (e) 6.62, (f)
8.26, (g) 9.9, (h) 11.5, (i) 13.5, (j) 14.8, (k) 16.4 and (l) 18×10-7 M Cys. Inset: (i) Photographs (a) before and (i) after
the addition 18×10-7 M of Cys curve (ii) Correlation diagram. 115
LOD = 1.83 nM
Cys
17. 116
UV-Vis spectra of 18×10-7 M Cys-AgNPs in the presence of different concentration Cu2+ (a) 0, (b) 0.817, (c) 1.63, (d)
2.44, (e) 3.25, (f) 4.06, (g) 4.86 and (h) 5.66×10-6 M Cu2+. Inset: (i) Photographs (a) before and (h) after the addition
5.66×10-6 M of Cu2+(ii) Correlation diagram.
LOD = 16 nM
Cu2+
18. 117
UV-Vis spectra of AgNPs in the presence of different concentration Cu2+ (a) 0, (b) 0.817, (c) 1.63, (d) 2.44, (e) 3.25,
(f) 4.06 and (g) 4.86×10-6 M Cu2+. Inset: Enlarge Scale.
19. 2.94×10-4M (750 fold) of
common interferences such as
L-Phenylalanine, L-Proline,
L-Histidine, L-Threonine,
L-Valine, L-Serine, L-Alanine,
Glycyl glycine, L-Glutamine,
D-Aspartic acid, Glycine,
Glutathione and L-methionine
above mention common
potential interference did not
interact for the detection of
3.32 × 10-7 M of L-Cysteine.
21
118
20. 4.89×10-4M (300 fold) of
common interferences such as
Na+ , K+ , Zn2+ , Fe2+ , Ni2+ , Fe3+ ,
Cd2+ , Mn2+ , Mg2+ , and Co2+
above mention common
potential interference did not
interact for the detection of
1.63 × 10-6 M of Cu2+.
21
119
23. 22
We have successfully synthesized Th-AgNPs at Solid state
method within 5 min
The synthesized Th-AgNPs was well characterized by several
techniques
Then, Th-AgNPs was used as probe for the detection of L-Cys
and Cu2+ corresponding LOD was found to be 1.83 and 16 nM
750 and 300 fold excess of common interferences did not
interfere for the detection of L-Cys and Cu2+ ion
Finally we have discuss possible mechanism of detection L-Cys
and Cu2+ ion
24. 23
Th in the presence of different concentration of Cys and
Cu2+ monitoring UV-vis spectrophotometer
Future characterisation HR-TEM, FT-IR, Mass, XRD and
DLS spectroscopy
Then, Sensor system applying real sample analysis
Preparation of paper based kit
Validation method
