Solid-state nuclear track detectors (SSNTDs) have found many applications in different areas of science and engineering. The more commonly used nuclear track materials include polyallyldiglycol carbonate (commercially available as CR-39), polycarbonate (commercially available as Makrofol) and cellulose nitrate (commercially available as LR 115). In the present thesis, we will study CR-39 SSNTDs for three different applications, namely: (1) the use of CR-39 SSNTDs as substrates in alpha-particle radiobiological experiments and we will focus on how to enhance the biocompatibility of chemically etched CR-39 SSNTDs; (2) creation of surface energy gradient surfaces by latent alpha-particle tracks in CR-39 SSNTDs; and (3) the use of alpha-particles irradiated and chemically etched CR-39 SSNTDs as stencils for micropatterning cell cultures. Chapter 1 will give the introduction and background information. Chapter 2 will present the studies of biocompatibility of chemically etched CR-39 SSNTDs. Alpha-particle radiobiological experiments involve irradiating cells with alpha particles and require thin biocompatible materials which can record alpha-particle traversals as substrates for cell cultures. The thinnest commercially available CR-39 detector is ~100 μm thick. In order for alpha particles with nominal energies (viz. 5 MeV) to penetrate the CR-39 films, their thickness should not be larger than 28.52 μm, which is the range of 5 MeV alpha particle in CR-39 SSNTDs. Chemical etching is employed to reduce the thickness of CR-39 SSNTDs from ~100 μm to below 28 μm. However, chemical etching will also change the surface properties of the films, which will in turn alter the biocompatibility. The biocompatibilities of chemically etched CR-39 SSNTDs using aqueous NaOH or NaOH/ehtanol are studied through the abundance and morphology of the cultured HeLa cells. The wetting properties of these etched CR-39 SSNTDs are also studied. The moderately hydrophobic CR-39 SSNTDs as well as the hydrophobic NaOH/ethanol-etched CR-39 SSNTDs are more biocompatible than the hydrophilic aqueous-NaOH-etched SSNTDs. Too small water contact angles, too large surface energy (g s ) or the polar component ( p ) g s do not favor the cell culture. On the other hand, the dispersive component ( d ) g s of the surface energy and the ratio ( d ) s p g s /g do not seem to significantly affect the biocompatibility. Chapter 3 will present our studies on the creation of surface energy gradient surfaces by latent alpha-particle tracks in CR-39 SSNTDs. Surface energy gradient surfaces with changes in the ratio between the polar component ( p ) g s to the dispersive component ( d ) g s of the surface energy ( ) g s have been successfully fabricated by irradiating CR-39 solid-state nuclear track detectors (SSNTDs) with 3 MeV alpha-particles with different fluence followed by irradiation with ultraviolet photons with 257 nm. The alpha-particle source has an activity of 0.1 μCi and the irradiation time ranges from 1 to 7 d. The contact angles for doubly distilled water, glycerin and ethylene glycol, as well as g s do not vary significantly with the alpha-particle irradiation. In contrast, p g s decreases steadily while d g s increases steadily, and the ratio d s p g s /g decreases significantly with the alpha-particle fluence. The changes are likely due to modifications of the molecular structure in the polymer surface by the alpha particles. Such surface energy gradient surfaces are of particular interest for establishing the relationship between the d s p g s /g ratio and the biocompatibility. Chapter 4 will present our studies on using alpha-particle irradiated and subsequent chemically etched CR-39 SSNTDs as stencils for micropatterning cell cultures. CR-39 films with a thickness of ~8 μm and pores with diameters of ~60 μm are generated by irradiating CR-39 SSNTDs with alpha particles of ~ 5 MeV and then by chemical etching. In practice, an etched CR-39 film with micropores of the desired size is attached onto the surface of a common Petri dish, and onto which cells are then cultured. This etched CR-39 film acts as a stencil which can selectively block the substrate from contacting the cell suspension only on the areas covered by the film, while leaving the substrate exposed to the cell suspension through the micropores. This simple method enables cell patterning without chemical modification of the substrate. Chapter 5 gives the summary and the conclusions.