Podloge za mikro-topografsko i galvanotropsko aksonalno vođenje

master's thesis

• Title (english): Substrates for microtopographic and galvanotropic axonal guidance
• Author: Karla Filipović
• Mentor: Vedran Đerek (mentor)
• Committee member: Vedran Đerek (predsjednik povjerenstva)
• Committee member: Matko Glunčić (član povjerenstva)
• Committee member: Emil Tafra (član povjerenstva)
• Committee member: Nenad Pavin (član povjerenstva)
• Committee member: Mario Basletić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Physics); Zagreb
• Defense date and country: 2024-07-09, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Physics

Abstract

Tijekom razvoja mozga aksoni rastu prema svom cilju s visokim stupnjem preciznosti. Za točno usmjeravanje odgovorne su kemijske, topografske i galvanotropske naznake. Istraživanje djelovanja vanjskih naznaka na vodenje aksona bitno je za moguće kliničke primjene, kao što su ubrzavanje regeneracije živčanih puteva nakon traumatskih ozljeda, ali i za znanstvena istraživanja kao što su karakterizacije živih neuralnih mreža. U ovom radu izradujemo podloge s različitim topografskim i galvanotropskim elementima koje se mogu koristiti za daljnje istraživanje aksonalnog vodenja. Za izradu topografskih naznaka koristimo nanosekundni i femtosekundni laser kojima mikrostrukturiramo površinu laserskom ablacijom. Podloge proizvodimo na komadima borosilikatnog stakla i silicija te promatramo efekte laserskih pulseva različite duljine i energije na dielektrični i poluvodički materijal. Za karakterizaciju uzoraka koristimo optički i kontaktni profilometar te pretražni elektronski mikroskop. Mjerimo ovisnosti volumena, promjera i dubine ablacijskog kratera o energiji pulsa te D2 metodom računamo minimalnu ekspoziciju. Za galvanotropsko vodenje koristimo organske elektrolitske fotokondenzatore (OEPC) koji su izradene od organskih poluvodiča. OEPC su optoelektronički stimulatori koji se koriste za kapacitivnu neurostimulaciju. Koristeći nanosekundni i kontinuirani laser uklanjamo dizajnirani uzorak p-n dvosloja s površine fotokondenzatora čime stvaramo inverzne fotokondenzatore. Karakteriziramo inverzne fotokondenzatore mjerenjem tranzijentnog električnog potencijala.

Abstract (english)

During brain development axons grow towards their target with a high degree of accuracy. Chemical, topographical and galvanotropic cues are responsible for their guidance. Research of external cues for axonal guidance is vital for the possible clinical applications, such as accelerating nerve regeneration after traumatic injuries, as well as for scientific research (e.g. characterization of living neural networks). We designed and produced substrates with different topographical and galvanotropic elements which can be used for the investigation of axonal guidance. Microstructuring of the surface is done by using nanosecond and femtosecond laser ablation. Materials used for the substrates are borosilicate glass (dielectric) and silicon (semiconductor) on which the effects of different duration and energy of laser pulses are studied. Characterization was done using an optical profilometer, a contact profilometer and a scanning electron microscope. Dependence of the ablated volume, the diameter and the depth of ablation craters for different pulse energies is measured. The ablation threshold fluence is determined by the D2 method. Organic electrolytic photocapacitors (OEPCs) were used for fabrication of the substrates with the galvanotropic cues. OEPCs are optoelectronic stimulators based on a p-n bilayer of organic semiconductors which are used for capacitive neurostimulation. Using a nanosecond and a continuous laser, a designed pattern of a p-n bilayer was removed from the surface of the photocapacitor, thus making an inverse photocapacitor. Characterization of said inverse photocapacitors is done by measuring the transient electric potential inside the physiological medium mimicking electrolyte.

• Keywords: aksonalno vođenje; nanosekundna ablacija; femtosekundna ablacija; laserska mikroobrada materijala; p-n dvosloj organskih poluvodiča; mjerenje tranzijentnog električnog potencijala
• Keywords (english): axonal guidance; nanosecond ablation; femtosecond ablation; laser micromachining; p-n bilayer of organic semiconductors; measuring transient electric potential
• Language: croatian
• URN:NBN: urn:nbn:hr:217:735890
• Project: Number: UIP-2019-04-1753; Title: Mikro i nano-strukture za 3D opto-bioelektroniku; Title: Micro- and nano-structures for 3D opto-bioelectronics; Acronym: 3Doptobio; Leader: Vedran Đerek; Jurisdiction: Croatia; Funder: Hrvatska zaklada za znanost; Funding stream: Installation Research Projects
• Study programme: Title: The University Integrated Undergraduate and Graduate Programme in Physics; Research Physics; specializations in: Research Physics; Course: Research Physics; Study programme type: university; Study level: integrated undergraduate and graduate; Academic / professional title: sveučilišni magistar fizike (sveučilišni magistar fizike)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2024-07-26 10:34:57