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This paper reviews the latest trends and applications of silicone in ophthalmology, especially related to intraocular lenses (IOLs). Silicone, or siloxane elastomer, as a synthetic polymer, has excellent biocompatibility, high chemical inertness, and hydrophobicity, enabling wide biomedical applications. The physicochemical properties of silicone are reviewed. A review of methods for mechanical and in vivo characterization of IOLs is presented as a prospective research area, since there are only a few available technologies, even though these properties are vital to ensure medical safety and suitability for clinical use, especially if long-term function is considered. IOLs represent permanent implants to replace the natural lens or for correcting vision, with the first commercial foldable lens made of silicone. Biological aspects of posterior capsular opacification have been reviewed, including the effects of the implanted silicone IOL. However, certain issues with silicone IOLs are still challenging and some conditions can prevent its application in all patients. The latest trends in nanotechnology solutions have been reviewed. Surface modifications of silicone IOLs are an efficient approach to further improve biocompatibility or to enable drug-eluting function. Different surface modifications, including coatings, can provide long-term treatments for various medical conditions or medical diagnoses through the incorporation of sensory functions. It is essential that IOL optical characteristics remain unchanged in case of drug incorporation and the application of nanoparticles can enable it. However, clinical trials related to these advanced technologies are still missing, thus preventing their clinical applications at this moment.

Deterministic and stochastic models of Brownian motion in ferrofluids are of interest to researchers, especially those related to drug delivery systems. The Brownian motion of nanoparticles in a ferrofluid environment was theoretically analyzed in this research. The state of the art in clinical drug delivery systems using ferromagnetic particles is briefly presented. The motion of the nanoparticles in an external field and as a random variable is elaborated by presenting a theoretical model. We analyzed the theoretical model and performed computer simulation by using Maple software. We used simple low-dimensional deterministic systems that can exhibit diffusive behavior. The ferrofluid in the gravitational field without the presence of an external magnetic field in the xy plane was observed. Control parameter p was mapped as related to the fluid viscosity. Computer simulation showed that nanoparticles can exhibit deterministic patterns in a chaotic model for certain values of the control parameter p. Linear motion of the particles was observed for certain values of the parameter p, and for other values of p, the particles move randomly without any rule. Based on our numerical simulation, it can be concluded that the motion of nanoparticles could be controlled by inherent material properties and properties of the surrounding media, meaning that the delivery of drugs could possibly be executed by a ferrofluid without an exogenous power propulsion strategy. However, further studies are still needed.

Predmet ove doktorske disertacije je razvoj analitičkog modela bioštampe nenjutnovskih mekih biomaterijala sa efektom stanjivanja usljed smicanja (shear thinning) za primenu u oftalmologiji. Razvijen je matematički model tangencijalnog napona za nenjutnovske gelove i fluide, primenom FENE modela, koji povezuje tangencijalni napon, pritisak, brzinu štampanja i brzinu smicanja, uzimajući u obzir viskoznost, trenje i adheziju, a parametri dobijeni eksperimentalno korišćeni su za analizu njihovih međusobnih odnosa u procesu 3D štampe. Eksperimentalni uzorci od elastičnog polimera sličnog PDMS silikonu i termoplastičnog poliuretana (TPU) dobijeni su primjenom SLA i FDM 3D štampe. Cilj istraživanja je određivanje korelacija između ulaznih procesnih parametara i izlaznih karakteristika štampanog materijala, kao i najuticajnijih faktora. Dobijeni rezultati ove doktorske disertacije obuhvataju analitički fizički modeli za objašnjenje karakteristika mekih materijala na osnovu parametara bioštampe, kao i analitički model stanjivanja usljed smicanja koji je povezan sa dimenzionom tačnošću štampanih struktura. Model Braunovog kretanja čestica analiziran je radi razvoja sistema za isporuku lekova u nanofluidima. Takođe su definisani optimalni parametari FDM 3D štampe za bolju dimenzionu tačnost, a utvrđena je i zavisnost trenja između slojeva u bioštampi od molekulske mase, temperature, normalnog opterećenja, brzine klizanja i prirode površine, kroz razvijeni analitički model. Istraživanje je pokazalo značajan uticaj brzine štampe na dimenzionu tačnost kod FDM tehnologije, određene su eksperimentalne mehaničke karakteristike finalnih uzoraka biomaterijala i razmotrene mogućnosti primene bioštampe za izradu intraokularnih sočiva. Razvijeni analitički model tangencijalnog napona pokazuje dobru saglasnost sa eksperimentalnim testovima pri malim brzinama smicanja i može se koristiti za okvirno definisanje parametara FDM 3D štampe radi poboljšanja dimenzione tačnosti, dok će buduća istraživanja biti usmerena na modeliranje pri visokim brzinama i nove kompozite.