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A single focus optical tweezer is formed when a laser beam is launched through a high numerical aperture immersion objective. This objective focuses the beam down to a diffraction-limited spot, which creates an optical trap where cells suspended in aqueous solutions can be held fixed. Spermatozoa, an often probative cell type in forensic investigations, can be captured inside this optical trap and dragged one by one across millimeter-length distances in order to create a cluster of cells which can be subsequently drawn up into a capillary for collection. Sperm cells are then ejected onto a sterile cover slip, counted, and transferred to a tube for DNA analysis workflow. The objective of this research was to optimize sperm cell collection for maximum DNA yield, and to determine the number of trapped sperm cells necessary to produce a full STR profile. A varying number of sperm cells from both a single-source semen sample and a mock sexual assault sample were isolated utilizing optical tweezers and processed using conventional STR analysis methods. Results demonstrated that approximately 50 trapped spermatozoa were required to obtain a consistently full DNA profile. A complete, single-source DNA profile was also achieved by isolating sperm cells via optical trapping from a mixture of sperm and vaginal epithelial cells. Based on these results, optical tweezers are a viable option for forensic applications such as separation of mixed populations of cells in forensic evidence.
This article was published in the following journal.
Name: PloS one
In this unit, we provide a clear exposition of the methodology employed to study dynamic responses in individual cells, using microfluidics for controlling and adjusting the cell environment, optical ...
Optical micromanipulation has become popular for a wide range of applications. In this work, a new type of optical micromanipulation platform, patterned optoelectronic tweezers (p-OET), is introduced....
Optical trapping of single particles or cells with the capability of in situ bio-sensing or genetic profiling opens the possibility of rapid screening of biological specimens. However, common optical ...
Block copolymer self-assembly has enabled the creation of a range of solution-phase nanostructures with applications from optoelectronics and biomedicine to catalysis. However, to incorporate such mat...
Although equal numbers of X and Y spermatozoa are produced during spermatogenesis, the sex chromosome ratio in ejaculated spermatozoa can be altered by exposure to endocrine-disrupting chemicals (EDCs...
The purpose of this research project is to determine whether or not the directional movement of spermatozoa is influenced by a pH gradient by examining spermatozoa in vitro.
The purpose of this study is to seek the presence of ZIKV in semen, to determine its localization and to assess the efficiency of spermatozoa processing methods to obtain virus free sperma...
Cryoballoon ablation is proven to be effective in pulmonary vein isolation in patients with paroxysmal atrial fibrillation. However, it is not certain that cryoablation is effective and sa...
A couple that does not achieve pregnancy though regular attempts for a year are defined infertile couple. This condition is caused by faulty functioning of the reproduction system of the h...
The aim of this study is to analyse the efficacy of MACS technique for the selection of spermatozoa and its effects on implantation, pregnancy and miscarriage rate. This study will be perf...
A technique that uses LASERS to trap, image, and manipulate small objects (biomolecules, supramolecular assembles, DENDRIMERS) in three dimensional space. (From Glossary of Biotechnology and Nanobiotechnology Terms, 4th ed.)
The use of light interaction (scattering, absorption, and fluorescence) with biological tissue to obtain morphologically based information. It includes measuring inherent tissue optical properties such as scattering, absorption, and autofluorescence; or optical properties of exogenous targeted fluorescent molecular probes such as those used in optical MOLECULAR IMAGING, or nontargeted optical CONTRAST AGENTS.
Products or parts of products used to detect, manipulate, or analyze light, such as LENSES, refractors, mirrors, filters, prisms, and OPTICAL FIBERS.
Chemical substances which inhibit the process of spermatozoa formation at either the first stage, in which spermatogonia develop into spermatocytes and then into spermatids, or the second stage, in which spermatids transform into spermatozoa.
Fluorescence microscopy utilizing multiple low-energy photons to produce the excitation event of the fluorophore. Multiphoton microscopes have a simplified optical path in the emission side due to the lack of an emission pinhole, which is necessary with normal confocal microscopes. Ultimately this allows spatial isolation of the excitation event, enabling deeper imaging into optically thick tissue, while restricting photobleaching and phototoxicity to the area being imaged.
Bioinformatics is the application of computer software and hardware to the management of biological data to create useful information. Computers are used to gather, store, analyze and integrate biological and genetic information which can then be applied...
The World Health Organization (WHO) definition of sexual health; "the state of physical, emotional, mental and social well-being related to sexuality; it is not merely the absence of disease, dysfunction and infirmity. Sexual health requires a posit...