Criminology

Forensic Biology

Forensic experts have been searching for a way to quickly and reliably identify the most
suited samples for DNA analysis. Enzyme and antibody-based serological assays are used in
traditional screening methods. The enzyme alpha-amylase, which has long been connected with
human saliva, is often used in forensic saliva testing. Some of these tests may be expensive and
time-consuming while relying on antibody-based serological testing can be error-prone. Only
speculative findings may be drawn from data derived from non-target biological fluids, cross-
reactivity, and non-specific binding events. Therefore, blood, menstrual blood, sperm, saliva,
vaginal material, and skin are all interests in multiplex immunochromatographic forensic
research.
Alternative light sources (ALS) may identify possible semen stains. Semen stains, as well
as other bodily fluids and other stains, will glow. BCIP may be used to swab and test these
luminous stains (5-Bromo-4-chloro-3-indolyl phosphate). The acid phosphatase present in
seminal fluid interacts with BCIP. The swabs will become turquoise blue if acid phosphatase is
present. Clothing and bedding are the most common items tested for BCIP (Holtkötter et al.,
2018). Semen or seminal fluid is presumed to be present in the BCIP test.
Creatinine testing is used to identify urine samples. In urine, creatinine may be detected.
A shift in hue from yellow to orange and back to yellow might be noted if creatinine is present.
A positive sample will change yellow, orange, then back to yellow, while a negative sample will
stay yellow during the whole process.
Microscopically identifying sperm may be done using Sperm Hyliter slide staining. A
response between an antigen and an antibody is another way Sperm HyliterTM works. It is
discovered that sperm heads respond to an antibody in the dye while being stained. The sperm

3
heads glow brilliant green due to this interaction (McKiernan, 2019). Staining all of the nuclei in
a sample is accomplished by adding a second dye. Because of this, the presence of sperm in a
sample will cause it to glow green or blue when seen under a microscope using two distinct
contrasts (FITC & DAPI). The fluorescence distinguishes the sperm heads from the surrounding
cells and detritus. Human sperm heads are the only ones affected by this response. It is essential
to check for the proper fluorescence, the appropriate size and form, and a little unstained region
of the sperm head when identifying sperm heads. In order to validate semen identification at the
BCA, sperm must be positively identified microscopically.
Detection and identification of body fluids is an essential part of forensic science and has
been used for many years at the crime scene and in the laboratory. Chemical-based testing has
been used for decades, but it has lacked specificity. Current methods for detecting bodily fluids,
such as RNA (mRNA and miRNA), epigenetics, spectroscopic techniques including Raman
spectroscopy and micro-spectrophotometry, biosensors, and immunochromatographic
approaches, are discussed in this overview, along with their advantages and disadvantages.
Technology like massively parallel sequencing may provide fresh insights into cell identification.
The PhadebasTM test is the BCA's presumptive saliva test. A sample's amylase activity
may be determined using this technique. Saliva has a high concentration of the enzyme amylase.
Water-soluble starch polymer, dyed blue, is the main ingredient of PhadebasTM tablets. Samples
containing amylase enzymes will break down the starch polymer in PhadebasTM tablets,
releasing blue color.
Blood may be presumptively tested for using phenolphthalein. Hydrogen peroxide,
ethanol, and phenolphthalein are among the substances employed. A redox reaction is used to
conduct a phenolphthalein test, and the chemicals begin in a reduced state. The heme group's

4
peroxidase activity causes the molecules to be oxidized. A robust pink hue shift is seen when
oxidation begins. The color change won't occur as long as there is no peroxidase activity.
Antisalivary amylase monoclonal antibodies are used in the Rapid Stain Identification
(RSID-Saliva) lateral flow immunochromatographic strip test to identify the presence of salivary
amylase rather than the enzyme's activity. RSD-Saliva is an extremely sensitive saliva analyzer
that can identify less than 1 microL of saliva. RSID-Saliva is accurate, repeatable, and highly
sensitive. Because of the high sensitivity of RSID-Saliva, just a tiny portion of a stain m


Place your order