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Besides the need for biomaterial surface modification to improve cellular attachment, laser-structuring is favorable for designing a new surface topography for external bone fixator pins or implants. The principle of this study was to observe how bioinspired (deer antler) laser-induced nano–microstructures influenced the adhesion and growth of skin cells. The goal was to create pins that allow the skin to attach to the biomaterial surface in a bacteria-proof manner. Therefore, typical fixator metals, steel, and titanium alloy were structured using ultrashort laser pulses, which resulted in periodical nano- and microstructures. Surface characteristics were investigated using a laser scanning microscope and static water contact angle measurements. In vitro studies with human HaCaT keratinocytes focused on cell adhesion, morphology, actin formation, and growth within 7 days. The study showed that surface functionalization influenced cell attachment, spreading, and proliferation. Micro-dimple clusters on polished bulk metals (DC20) will not hinder viability. Still, they will not promote the initial adhesion and spreading of HaCaTs. In contrast, additional nanostructuring with laser-induced periodic surface structures (LIPSS) promotes cell behavior. DC20 + LIPSS induced enhanced cell attachment with well-spread cell morphology. Thus, the bioinspired structures exhibited a benefit in initial cell adhesion. Laser surface functionalization opens up new possibilities for structuring, and is relevant to developing bioactive implants in regenerative medicine.

Abstract Background Loosening of prostheses and functional disorders represent a far-reaching problem in the clinic, and the long-term outcomes are essentially determined by wear. Despite all advances, up to 10% of prostheses still fail after 10 years. In particular, more active patients show increased revision rates. Methods The objective of this thesis is to examine whether the applied microstructures of the articulating surfaces can lead to a reduction in abrasion. Three different structural geometries (dimples, offset lines, grid lines) were defined. In an experimental test setup according to DIN ISO 6474 (Deutsches Institut für Normung, International Organization for Standardization), a tribological test of metal and ceramic pairings was performed using two-dimensional ring-on-disc (RoD) tests. Results In both material groups, the structuring had a positive effect on the wear behaviour. In the ceramic group, an abrasion reduction of 22.6% was achieved. However, it is important to take into account the limited informative value due to the hardness of the material. Two of the three Cobalt-Chrome-Molybdenum (CoCrMo) structure geometries (grids, offset lines) also showed a significant reduction in abrasion compared to the reference group, with a maximum wear reduction of 55.5%. Conclusion By reducing abrasion, surface structuring could be used to extend the life of prostheses and minimise the number of revisions.

The microstructuring of surfaces is a highly researched field that is aimed at enhancing the tribological behavior of sliding surfaces such as artificial joints, which are subject to wear. Lubrication of the joint interface plays a key role in the wear process, although the mechanisms of lubrication are quite complex. In order to improve the lubrication, the surfaces of the articulating components can be modified by pulsed femtosecond-laser microstructuring. Through microstructuring, the apparent dynamic viscosity of the synovial fluid between the artificial joint can be increased due to its non-Newtonian properties. This may lead to better hydrodynamic lubrication and, therefore, reduced particle abrasion. Femtosecond laser-induced microstructures were investigated in a modified rheometer setup featuring a reduced gap size in order to reproduce and measure the interface between fluid and implant surface more accurately. As a test fluid, a synovial fluid substitute was used. The study has shown that an increase in the viscosity of the synovial fluid substitute can be achieved by microstructuring. Compared to a smooth implant surface, the apparent viscosity of the synovial fluid substitute increased by over 30% when ring-shaped microstructures of 100 µm diameter with an aspect ratio of 0.66 were implemented.

We developed a confined microfluidic cell culture system with a bottom plate made of a microscopic slide with planar platinum sensors for the measurement of acidification, oxygen consumption, and cell adhesion. The slides were commercial slides with indium tin oxide (ITO) plating or were prepared from platinum sputtering (100 nm) onto a 10-nm titanium adhesion layer. Direct processing of the sensor structures (approximately three minutes per chip) by an ultrashort pulse laser facilitated the production of the prototypes. pH-sensitive areas were produced by the sputtering of 60-nm Si3N4 through a simple mask made from a circuit board material. The system body and polydimethylsiloxane (PDMS) molding forms for the microfluidic structures were manufactured by micromilling using a printed circuit board (PCB) milling machine for circuit boards. The microfluidic structure was finally imprinted in PDMS. Our approach avoided the use of photolithographic techniques and enabled fast and cost-efficient prototyping of the systems. Alternatively, the direct production of metallic, ceramic or polymeric molding tools was tested. The use of ultrashort pulse lasers improved the precision of the structures and avoided any contact of the final structures with toxic chemicals and possible adverse effects for the cell culture in lab-on-a-chip systems.

Background: Suboxone (Buprenorphine/naloxone) is a novel drug used in opiate substitution therapy. In Hungary, it was introduced in November 2007. Suboxone is a product for sublingual administration containing the partial mu-receptor agonist buprenorphine and antagonist naloxone in a 4:1 ratio., Objective: Objectives of our study were to monitor and evaluate the effects of Suboxone treatment., Method: 6 outpatient centers participated in the study, 3 from Budapest and 3 from smaller cities in Hungary. At these centers, all patients entering Suboxone maintenance therapy between November 2007 and March 2008, altogether 80 persons (55 males, 35 females, mean age = 30.2 years, SD=5.48) were included in the study sample. During the 6-month period of treatment, data were collected 4 times; when entering treatment, 1 month, 3 months, and 6 months after entering treatment. Applied measures were the Addiction Severity Index, SCID-I, SCID-II, Hamilton Depression Scale, Hamilton Anxiety Scale, STAI-S State Anxiety Inventory, Beck Depression Inventory, Heroin Craving Questionnaire, WHO Well-being Inventory, Perceived Stress Scale, ADHD retrospective questionnaire, TCI short version, and Ways of Coping questionnaire., Results: Nearly fourth of the altogether 80 heroin dependent patients (18 persons, 22.5%) dropped out of treatment during the first month (the majority, 12 persons [15%] during the first week) or chose methadone substitution instead. Following this period however, dropout rate decreased and the six-month treatment period was completed by 32 patients (40%). During the first month of treatment significant positive changes were experienced in all studied psychological and behavioral dimensions that proved to be stabile throughout the studied period., Conclusions: According to the early experience with Suboxone treatment, it is a well tolerable and successfully applicable drug in the substitution therapy of opiate addicts. A critical phase seems to be the first one or two weeks of treatment. Dropout rate is high during this early period, while after a successful conversion clients presumably remain in therapy for a long period. At the beginning of administration special emphasis must be put on informing patients, especially concerning withdrawal symptoms that might be present during the first week, which highly contributes to better retention in treatment.