Abstract
For years, Luminol has been the preferred organic compound for blood detection test at crime scenes. However, Luminol has a short shelf life, destroys DNA evidence in forensic investigations, and is highly costly, according to reports. The nanoparticles of gold (AuNPs), silver (AgNPs), and palladium (PdNPs) were investigated as luminol enhancers for detecting blood traces at crime scenes. These nanoparticles were prepared using a green synthesis method in which the components of Crinum Macowanii bulb extracts served as reducing agents. Fourier transform infrared (FTIR), X-ray diffraction (XRD), Transmission electron microscopy (TEM), Zeta potential, and Ultraviolet/Visible spectroscopy were used to characterize the nanoparticles.
Face-centred cubic crystalline (Fcc) forms were displayed by the three types of nanoparticles. AuNPs, AgNPs and PdNPs showed UV-Vis absorption peaks of 538nm, 415nm, and 375 nm, respectively. The TEM study identified a variety of nanospheres, triangular prisms, pentagonal, and rod morphologies. The surface charges of the nanoparticles were discovered to be -29.05 mV, -15.5 mV, -23.34 mV for the AgNPs, AuNPs, and PdNPs, respectively. The spectrum of plant extract synthesized AgNPs (Figure 4.2a) exhibits prominent peaks at 3437, 2960, 2854, 1632.64, 1384, and 1086 cm-1, and the peaks from synthesised AuNPs (Figure 4.2b) showed bands at 3275 cm−1, 2880 cm−1, 1628 cm−1, 1396 cm−1, and The spectrum of synthesised PdNPs (Figure 4.2c) shows some pronounced absorbance bands at around 3250, 2922, 2150, 1680, and 1110 cm-1 that represent OH and N-H stretch; CH alkane band, O-H strong, C=O bond for aldehydes & ketones, N-H stretch; N-O stretch, and C-N stretch for aromatic amines, respectively.
The prepared nanoparticles were added to luminol to compare chemiluminescence signals under UV light and in darkness. Enhanced luminol and alternative materials were used to detect blood traces (represented by commercial haemoglobin) in the laboratory using cotton balls, and the surface under short wavelength UV-light (254nm) and long-wavelength UV-light (365nm) and in darkness. The results demonstrated that AgNPs enhanced the luminol signal best due to longer-lasting chemiluminescence signals than PdNPs and AuNPs under UV light, light, and dark conditions. The active functional groups and SPR vibrations bands on the surface of
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the nanoparticles demonstrated that the aqueous bulb extract improved the chemiluminescence characteristics. Alternative polar and non-polar materials of Crinum Macowanii bulb extracts were tested as well for blood detection and also show that it is a promising material for blood detection, but these are still not as effective as luminol and require further investigations by isolating the components responsible for the chemiluminescence.