Preliminary Development of an Integrated Microchip for Multipurpose Caenorhabditis elegans Studies

Abstract

Despite prolonging the life of humans the number of people suffering from neurodegenerative diseases and cancer increases significantly Therefore postponing aging to decrease the incidence of diseases and provide better prognosis is important Given its high similarity with humans in terms of genes the multicellular organism Caenorhabditis elegans is the simplest model animal widely used in many research fields such as neurology genetic engineering developmental biology and pharmaceutics However research on the nematode still requires painstaking operations thus reducing the throughput and efficiency To address the problem an integrated microchip was proposed in this study as a solution This study is divided into three parts namely worm exercise cancer screening and immobilization Regardless of whether microsurgery fluorescent imaging or physiological observation is used in this tiny organism immobilization is an essential step However minimal work has been performed Hence immobilization is an essential function fabricated on microchips An immobilization technique based on the combined use of an optoelectric device and a 20% w/v thermos-reversible hydrogel solution Pluronic F-127 was developed first Second the optoelectric device was coated with a photoconductive layer to allow the local circuit channels to be rapidly switched by optical illumination After simultaneously applying light and electric fields under optimal conditions the hydrogel reached gelation within 4 s and the immobilized C elegans appeared to resume its full locomotion within 1 s after the light was switched off The gelation region and location could be manipulated by changing the laser size and illuminated region According to the assessments worms should not be exposed to the hydrogel environment for more than 3 h Given the thermo-reversible property of PF-127 the sample was also conserved in the entire experiment Aside from C elegans this technique can be applied to other microorganisms Exercise not only makes an organism more energetic during the aging process; it can also postpone the occurrence of degenerative diseases Short-wavelength light elicits a photophobic movement-reversal response from C elegans Rather than using the electrotaxis method ultraviolet light was introduced to keep C elegans swimming to achieve the effect of exercise Therefore the design of the channel was simplified significantly After a 4 min delay in the droplet worms that received stimuli of 5 s UV light every 2 min for 8 min accomplished 20 min of continuous exercise Cancer is another issue linked with human aging We placed C elegans in the supernatant of Caco-2 and HeLa cell line culture medium separately to examine the biomechanical performance of C elegans Worms in the cancer cell culture medium tended to swim oddly instead of the normal forward movement The body bend frequency and unit kinetic power decreased significantly The results contribute to the highly developed chemosensory system of C elegans Therefore using C elegans as a sensor for cancer screening might help in the early diagnosis and successful treatment of the disease The proposed integrated chip can be subsequently performed for multipurpose analyses Thus the mechanism by which C elegans reacts to the secretion of cancer cells and its relationship with exercise antioxidants and aging must be determined The results are expected to provide information on the treatment of degenerative diseases and cancer in higher animal forms

Date of Award	2017 Jul 19
Original language	English
Supervisor	Han-Sheng Chuang (Supervisor)