| dc.description.abstract | A fingerprint is an impression left by the friction ridge of a finger. The friction ridges are
present on overall surface of the fingers that leads to the finger-impressions. The impressions
are present on the fingers, also present on the toes and soles of the feet as well as on the
hands and palms. The fingerprint patterns are distinctive, till date, it has not been observed
that any two people, including identical monozygotic twins, have the same fingerprints. The
fingerprints are unaffected by superficial wounds, and the same pattern or design persists
even after new skin has grown. When we touch any surface or objects, we leave imprints on
it. These may or may not be visible prints. The invisible finger impressions are developed
using various powder dusting and chemical methods like Iodine fuming, ninhydrin,
cyanoacrylate, silver nitrate method. The traditional powder-dusting method has some
disadvantages in terms of low sensitivity, less contrast, toxic in nature, and high
autofluorescence intrusion. Therefore, to overcome these disadvantages and to get more
accurate and precise results the use of nanoparticles has come into practice as a better choice.
The present study focuses on the synthesis of nanoparticles using ecofriendly resources. From
the two compounds, Silica and Graphene nanoparticles has been synthesized. The
Mesoporous Silica nanoparticles (MSNPs) was synthesized by sol-gel method whereas,
Graphene Nanosheets (GNS) was synthesized by pyrolysis technique. For the synthesis of
MSNPs, 0.055 M n-hexadecyl-trimethylammonium bromide (CTAB) aqueous solution was
prepared in 10 mL MilliQ water under vigorous stirring for 30 min followed by heating at
60°C for 15 min and cooled to room temperature and further added to a solvent mixture
containing 5 mL of methanol, 95 mL of MilliQ water, 3 mL of ammonium hydroxide
(NH4OH), 20 mL of ethyl acetate (CH3COOC2H5) under stirring condition and then 300 μL
of tetraethyl orthosilicate (TEOS) was added to the reaction solution. The resulting solution
was stirred for 12 hours. The synthesized MSNPs were washed with excess ethanol and
stored in 40 mL ethanol until further use. The CTAB was extracted by adjusting the pH to 1.6
and stirring for 3 hours at 60 °C and washed using ethanol. The pellet was dispersed in 20 mL
of ethanol and stored at room temperature. The Graphene nanosheets were synthesized using
chickpeas as a precursor by pyrolysis method. The 2 g of powdered chickpea sample was put
in a capped quartz boat and heated at 800∘C for 2 hours at a heating rate of 5o/ min under an
inert environment. Such synthesized soot was collected and treated with nitric acid to
introduce hydrophilic groups. Typically, 1 g of soot was taken in 100 mL nitric acid (60%)
and reflux for 12 hours. The supernatant was collected via centrifugation and evaporated at a
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water bath until a slurry was formed. Afterward, 500 mL water was added to it and
evaporated, this process was repeated to remove excess acid. When pH reached 7.0, the slurry
was dried at room temperature and GNS were collected (yield 60%). The characterization of
both the nanoparticles for various factors were done by FTIR, XRD, SEM, TEM, HR-TEM,
Raman spectroscopy, EDS, UV-Vis spectrophotometer and Fluorescence microscopy. The
synthesized nanoparticles were used for the development of latent finger-impressions on
various porous and non-porous surfaces like glass, paper, wooden surface, steel cup, and
plastic lid. MSNPs and GNS developed latent fingerprints on non-porous surfaces with clear
appearance of class and individual characteristics, whereas fingerprints are not developed on
porous surfaces. | en_US |
