Sperm selection is a clinical need for guided fertilization in men with low-quality semen. In this regard, microfluidics can provide an enabling platform for the precise manipulation and separation of high-quality sperm cells through applying various stimuli, including chemical agents, mechanical forces, and thermal gradients. In addition, microfluidic platforms can help to guide sperms and oocytes for controlled in vitro fertilization or sperm sorting using both passive and active methods. Herein, we present a detailed review of the use of various microfluidic methods for sorting and categorizing sperms for different applications. The advantages and disadvantages of each method are further discussed and future perspectives in the field are given.
This is an open access article under the terms of the Creat ive Commo ns Attri bution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
A nanocomposite of graphene oxide and gold nanourchins has been used here to modify the surface of a screen-printed carbon electrode to enhance the sensitivity of the electrochemical DNA detection system. A specific single-stranded DNA probe was designed based on the target DNA sequence and was thiolated to be self-assembled on the surface of the gold nanourchins placed on the modified electrode. Doxorubicin was used as an electrochemical label to detect the DNA hybridisation using differential pulse voltammetry (DPV). The assembling process was confirmed using scanning electron microscopy (SEM) imaging, cyclic voltammetry (CV), and the EIS method. The high sensitivity of the proposed system led to a low detection limit of 0.16 fM and a wide linear range from 0.5 to 950.0 fM. The specificity of the DNA hybridisation and the signalling molecule (haematoxylin) caused very high selectivity towards the target DNA than other nonspecific sequences.
K E Y W O R D S biosensors, DNA, electrochemical sensors, nanocomposites
| INTRODUCTIONDNA sequences are essential biomarkers in medical and biological sciences, and any change in their sequence can be a sign of a biological situation or possibly a disease [1-3]. However, another application of DNA detection/assessment is to identify or confirm a specific organism in an anonymous sample that can be harmful to health, against a particular country's law or religious beliefs. About the last case, pork meat and other byproducts such as gelatin are banned in religions, and therefore, the detection of those products can be an essential need in their import and marketing strategies [4-6]. There are methods for assessing or quantifying DNA sequences, including but not limited to electrophoresis, polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), immunohistochemistry, DNA sequencing, highperformance liquid chromatographic (HPLC), Liquid chromatography-mass spectrometry (LC-MS), biosensors, etc. [7,8].DNA biosensors and nanobiosensors combine the advantages such as specificity of DNA hybridisation methods and enhanced sensitivity brought by using nanomaterials.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
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