Obdelovanje površin kovin za kontrolirano adhezijo bakterij : poročilo o raziskavi

Lukač, Sebastjan (author), Bohinc, Klemen (mentor), Godič Torkar, Karmen (comentor), Sever Škapin, Andrijana (comentor)

Uvod: Interakcije med mikroorganizmi in površino kontaktnega materiala igrajo pomembno vlogo v različnih panogah. Površine materialov so lahko kontaminirane z različnimi mikroorganizmi, ki se pod določenimi pogoji odlagajo na površino in tako pričnejo s tvorbo biofilma, ki ima lahko negativni vpliv na zdravje in okolico. Premazi in tanke prevleke lahko zmanjšajo bakterijsko pritrditev, tvorbo biofilma ter negativno vplivajo na bakterijsko kolonizacij. Namen: Spremeniti površino jekla z jedkanjem ali premazovanjem ter ugotavljati vliv modifikacije površine na pritrjevanje bakterije S. aureus. Metode dela: Uporabljen material je bil nerjavno jeklo AISI 316 in jeklo v obliki ploščic, dimenzije 10 mm × 10 mm. Izbranim ploščicam smo spremenili površino in jih razdelili v štiri skupine: 1. AISI 316 brez obdelave, 2. AISI 316 mehansko jedkan z brusilnim papirjem tipa granulacije P1200, 3. AISI 316 kemično jedkan z 1 mol H2SO4,4. jeklo s premazom iz srebra. Na ploščicah z modificirano površino smo izvedli meritve hrapavosti, trdote in kontaktnega kota. Intenzivnost pritrjevanja bakterijskih celic smo ugotavljali z merjenjem absorbance sproščenega kristal vijoličnega barvila iz barvanih celic, pritrjenih na poskusnih ploščicah po 10 urah inkubacije in s vrstičnim elektronskim mikroskopom, kjer smo pregledali in fotografirali površino. Rezultati: Najbolj hrapavo površino smo izmerili jeklu s premazom iz srebra, sledi mehansko jedkan AISI 316, nato neobdelan AISI 316, kemično jedkan AISI 316 ima najbolj gladko površino. Po 10 ur inkubacije, je največ bakterij bilo pritrjenih na površini mehansko jedkanega nerjavnega jekla, na površini neobdelanega nerjavnega jekla je bilo pritrjenih manj bakterij, najmanj bakterij je bilo pritrjenih na jeklu s premazom iz srebra in kemično jedkanem nerjavnem jeklu. Razprava in sklep: Rezultati so pokazali vpliv topografije materiala na stopnjo pritrditve bakterij. Vzporedno s hrapavostjo narašča tudi število pritrjenih bakterij. Razlog za to je najverjetneje večja površina materiala pri večji hrapavosti, prav tako pa so bakterije v tem primeru bolj zaščitene proti zunanjimi dejavnikom. Število pritrjenih bakterij na površino materiala lahko zmanjšamo, če material zaščitimo s srebrom, saj srebro negativno vpliva na bakterijsko pritrditev in na že pritrjene bakterije.

• Language: Slovenian
• Keywords: Staphylococcus aureus, adhezija, nerjavno jeklo, jedkanje, srebro
• Work type: Bachelor thesis/paper
• Organization: ZF - Faculty of Health Sciences
• Year: 2017
• PID: 20.500.12556/RUL-95555
• COBISS.SI-ID: 5307755
• Publication date in RUL: 20.09.2017

Secondary language

• Language: English
• Title: Processing the surface of metal for controlled bacterial adhesion : research report

Abstract

Introduction: Interaction between microorganism and the surface of the contact material plays an important role in various industries. The surfaces of the materials can be contaminated with certain micro-organism, which under certain conditions are deposited to the surface, thus starting with the formation of a biofilm, which may have negative impact on health and environment. Coatings can reduce bacterial adheison, biofilm formation and may have negative affect on bacterial dolonization. Purpose: Change the surface of the steel with etching or coating and determine the effect of surface modification on adhesion of S. aureus. Methods: The material used, was stainless steel AISI 316 and steel in the form of tiles measuring 10×10 mm. The surfaces were changed and divided into four groups: 1. AISI 316 without treatment, 2. AISI 316 mechanically sanded with granulation type P1200, 3. AISI 316 chemically treated with 1 mol H2SO4, 4. Steel with a silver coating. On the modified surface tiles, measurement of rougness, hardness and contact angle were performed. The intensification of the bacterial cell attachment was determined by measuring the absorbance of the released crystal violet color from colored cell fixated on the test plates after 10 hours of incubation and with scanning electron microscope, where we examined and photographed the surface. Results: The results of the rougness showed that the tiles from the roughest to the smoothest are followed in the following order: silver-coated steel, AISI 316 mechanically etched, AISI 316 without modification, AISI 316 chemically etched. After 10 hours of incubation, most bacteria were attached to the mechanically treated surface, fewer bacteria were attached to untreated surfface of the stainless steel, the least bacteria were attached to silver-coated steel and chemically treated stainless steel. Discussion and conclusion: The results showed the influence of the topography of the material on the degree of bacterial adheison. In parallel with rougness, the number of attached bacteria is also increasing. The reason fort his is most likely a large surface area of the material at greater rougness and that bacteria are more protected against external factors. The number of bacteria attached to the surface of the material can be reduced if the material is protected with silver, because silver has a negative effect on the bacterial adheison and on the already attached bacteria.

• Keywords: Staphylococcus aureus, adhesion, stainless steel, etching, silver