ß-Tricalcium Phosphate-Modified Aerogel Containing PVA/Chitosan Hybrid Nanospun Scaffolds for Bone Regeneration.

Electrospinning has recently been recognized as a potential method for use in biomedical applications such as nanofiber-based drug delivery or tissue engineering scaffolds. The present study aimed to demonstrate the electrospinning preparation and suitability of ß-tricalcium phosphate-modified aerogel containing polyvinyl alcohol/chitosan fibrous meshes (BTCP-AE-FMs) for bone regeneration under in vitro and in vivo conditions. The mesh physicochemical properties included a 147 ± 50 nm fibrous structure, in aqueous media the contact angles were 64.1 ± 1.7°, and it released Ca, P, and Si. The viability of dental pulp stem cells on the BTCP-AE-FM was proven by an alamarBlue assay and with a scanning electron microscope. Critical-size calvarial defects in rats were performed as in vivo experiments to investigate the influence of meshes on bone regeneration. PET imaging using 18F-sodium fluoride standardized uptake values (SUVs) detected 7.40 ± 1.03 using polyvinyl alcohol/chitosan fibrous meshes (FMs) while 10.72 ± 1.11 with BTCP-AE-FMs after 6 months. New bone formations were confirmed by histological analysis. Despite a slight change in the morphology of the mesh because of cross-linking, the BTCP-AE-FM basically retained its fibrous, porous structure and hydrophilic and biocompatible character. Our experiments proved that hybrid nanospun scaffold composite mesh could be a new experimental bone substitute bioactive material in future medical practice.

Development of an enzymatic reactor applying spontaneously adsorbed trypsin on the surface of a PDMS microfluidic device.

Herein, a microfluidic device (MD) containing immobilized trypsin for rapid and efficient proteolysis was described. Trypsin was immobilized via non-specific protein adsorption onto the hydrophobic poly(dimethylsiloxane) (PDMS) channel wall of the MD. Peptide mapping of bovine serum albumin (BSA) samples was carried out to estimate the stability of trypsin adsorbed on PDMS surface. Peptide maps of BSA samples were obtained by capillary zone electrophoresis (CZE), the RSD% for migration times were under 1%. Several proteins (hemoglobin, myoglobin, lysozyme, and BSA) in a wide molecular size range (15-70 kDa) were digested efficiently with ∼50 s contact time. The number of separated peaks correlated well with the expected number of peptides formed in the complete tryptic digestion of the proteins. Peptide mass fingerprinting of BSA and human serum was carried out. Trypsin retained its activity for 2 h; within this period, the MD can be used for multiple digestions. The main properties of this device are simple channel pattern, simple immobilization procedure, regenerability, and disposability; all these features make this MD one of the simplest yet applicable enzymatic microreactors. Graphical abstract Development of microfluidic device including a serpentine channel as an enzyme reactor for protein digestion.

[Binding properties of components removable from dental base plate, analysed by Fourier-Transform Surface Plasmon Resonance (FT-SPR) method]. / Fogsor alaplemezbol kioldódó allergének kötodésének vizsgálata Fourier-Transzformációs Felületi Plazmon Rezonancia (FT-SPR) módszerrel.

In parallel with the emergence of new dental materials the number of allergic diseases is continuously increasing. Extremely small quantities of the allergens are capable to inducing an allergic reaction. Therefore it is particularly important to examine these materials as antigens and investigate their binding properties to proteins (e.g. formaldehyde, methacrylic acid, benzoyl-peroxide...). The Fourier Transform Surface Plasmon Resonance Spectroscopy (FT-SPR) is a suitable examination method for this type of procedure. FT-SPR measurement is performed at a fixed angel of incident light, and reflectivity is measured over a range of wavelength in the near infrared. The advantages of this method are the outstanding sensitivity, the label-free detection capability and the possibility of the real-time testing procedure. Formaldehyde and methacrylic acid are among the most common dental allergens. In our study we examined these molecules by FT-SPR spectroscopy. The aim of this work was to investigate the suitability of this method to the detection of these materials, with special focuses on the analysis and evaluation concentration-dependent measurements. Different concentrations (0.01 %-0.2%) of formaldehyde and methacrylic acid solutions were measured. The individual spectra were measured for all of the solutions, and calibration curves were calculated for the materials for the possibility of the determination of an unknown concentration. The results confirmed that the method is theoretically capable to detect hundred-thousandths scale concentration-changes in the solution flowing above the SPR-chip. The concentration-dependent studies had proved that the method capable to measure directly these materials and can provide appropriate calibration for quantitative determination. These experiments show the broad applicability of the FT-SPR method, which can greatly facilitate the mapping and understanding of biomolecular interactions in the future.

[Comparative study of polymerization shrinkage and related properties of flowable composites and an unfilled resin]. / Folyékony kompozitok és töltetlen kompozit gyanta polimerizációs zsugorodásának összehasonlító vizsgálata.

OBJECTIVES: The polymerization shrinkage and shrinkage stress of dental composites are in the center of the interest of researchers and manufacturers. It is a great challenge to minimize this important property as low as possible. Many factors are related and are in complicated correlation with each other affecting the polymerization shrinkage. Polymerization shrinkage stress degree of conversion and elasticity has high importance from this aspect. Our aim was to study the polymerization shrinkage and related properties (modulus of elasticity, degree of conversion, shrinkage stress) of three flowable composite (Charisma Opal Flow, SDR, Filtek Ultimate) and an unfilled composite resin. MATERIALS AND METHODS: Modulus of elasticity was measured using three point flexure tests on universal testing machine. The polymerization shrinkage stress was determined using bonded-disc technique. The degree of conversion measurements were performed by FT-IR spectroscopy. And the volumetric shrinkage was investigated using Archimedes principle and was measured on analytical balance with special additional equipment. RESULTS: The unfilled resin generally showed higher shrinkage (8,26%), shrinkage stress (0,8 MPa) and degree of conversion (38%), and presented the lowest modulus of elasticity (3047,02MPa). CONCLUSIONS: Highest values of unfilled resin correspond to the literature. The lack of fillers enlarges the shrinkage, and the shrinkage stress, but gives the higher flexibility and higher degree of conversion. Further investigations needs to be done to understand and reveal the differences between the composites.

Composition and characterization of in situ usable light cured dental drug delivery hydrogel system.

Biodegradable polymers are compatible, permeable and nontoxic, thus they can provide a useful tool for drug delivery or tissue engineering. These polymers can form hydrogels, which are suitable vehicles for different types of materials e.g. drugs, bioactive molecules or cells. In the case of dentistry, photopolymerization is an obvious method to obtain in situ useable devices which can provide a more efficient way of tailoring drug release. A hydrogel system was developed based on poly-gamma-glutamic acid that was modified with methacryloyl groups to achieve this purpose. The resulting new reactive structure was proved by NMR spectroscopy. The swelling ratio of this type of hydrogel has been found remarkable, over 300 % after 24 h, and it can release 5 ng/mm(2) metronidazole. The prepared hydrogels were nontoxic as viability, cytotoxicity tests and cell morphology investigations proved it. These results render this model system an excellent candidate for use as an in situ curing local drug delivery device. The new photoactive system can be utilized in the treatment of periodontal diseases or raising the effectiveness of drugs used only in the minimal effective dose.

[Comperative study of implant surface characteristics]. / Implantátumok felületi sajátosságainak összehasonlító vizsgálata.

The osseointegration between the implant and its' bone environment is very important. The implants shall meet the following requirements: biocompatibility, rigidity, resistance against corrosion and technical producibility. In our present study surface morphology and material characteristics of different implants (Denti Bone Level, Denti Zirconium C, Bionika CorticaL, Straumann SLA, Straumann SLA Active, Dentsply Ankylos and Biotech Kontact implant) were investigated with scanning electron microscopy and energy-dispersive X-ray spectroscopy. The possible surface alterations caused by the manufacturing technology were also investigated. During grit-blasting the implants' surface is blasted with hard ceramic particles (titanium oxide, alumina, calcium phosphate). Properties of blasting material are critical because the osseointegration of dental implants should not be hampered. The physical and chemical features of blasting particles could importantly affect the produced surfaces of implants. Titanium surfaces with micro pits are created after immersion in mixtures of strong acids. On surfaces after dual acid-etching procedures the crosslinking between fibrin and osteogenetic cells could be enhanced therefore bone formation could be directly facilitated on the surface of the implant. Nowadays there are a number of surface modification techniques available. These can be used as a single method or in combination with each other. The effect of the two most commonly used surface modifications (acid-etching and grit-blasting) on different implants are demonstrated in our investigation.

Combined Release of Antiseptic and Antibiotic Drugs from Visible Light Polymerized Biodegradable Nanocomposite Hydrogels for Periodontitis Treatment.

The in situ application of the combination of different types of drugs revolutionized the area of periodontal therapy. The purpose of this study was to develop nanocomposite hydrogel (NCHG) as a pH-sensitive drug delivery system. To achieve local applicability of the NCHG in dental practice, routinely used blue-light photopolymerization was chosen for preparation. The setting time was 60 s, which resulted in stable hydrogel structures. Universal Britton-Robinson buffer solutions were used to investigate the effect of pH in the range 4-12 on the release of drugs that can be used in the periodontal pocket. Metronidazole was released from the NCHGs within 12 h, but chlorhexidine showed a much longer elution time with strong pH dependence, which lasted more than 7 days as it was corroborated by the bactericidal effect. The biocompatibility of the NCHGs was proven by Alamar-blue test and the effectiveness of drug release in the acidic medium was also demonstrated. This fast photo-polymerizable NCHG can help to establish a locally applicable combined drug delivery system which can be loaded with the required amount of medicines and can reduce the side effects of the systemic use of drugs that have to be used in high doses to reach an ideal concentration locally.

[Synthesis of nanoparticles for dental drug delivery systems]. / Fogászatban alkalmazható hatóanyagok leadására alkalmas nanorészecskék szintézise.

Modern drug delivery systems are designed for targeted controlled slow drug release. Up to now polymer based hydrogels have been applied in dentistry, which systems can affect the rate of the release due to their structure. Recently, intensive research for other methods is performed all over the world in order to improve the effectiveness of delivery systems. Nanotechnology is one of the most dynamically developing disciplines and is a powerful tool to increase the bioavailability of drugs. The aim of this work is to synthesise biocompatible nanoparticles by free radical initiated copolymerization of the monomers, 2-hydroxyethyl methacrylate (HEMA) and polyethyleneglycol dimethacrylate (PEGDMA) in aqueous solution, which can support the formation of nanoparticles that can be used as a drug delivery system for dental applications. The polymer-based nanoparticles were prepared via micellar polymerisation, which resulted a well dispersible white powder material. The size of particles was determined by Dynamic Laser Light Scattering (DLS) and Scanning Electron Microscopy (SEM). The size of particles is in range of 50-180 nm, measured by SEM. These values are commensurable with the results obtained by DLS experiments, where two size ranges were observed, as 40 +/- 15 nm and 180 +/- 30 nm. The nanoparticles are suitable for incorporation into a hydrogel matrix and to design new drug delivery devices for dental applications.

[Synthesis and compression strength of hydrogels]. / Hidrogélek szintézise és nyomási szilárdságuk vizsgálata.

The purpose of the present investigation was the synthesis of crosslinked polymers and the assay of the effect of the monomer ratio to the compression values. Hydrogels were made by free radical photoinitiation from 2-hydroxyethyl metachrylate (HEMA) monomer, poly(ethylene glycol) dimethacrylate (PEG-DMA) crosslinker and sodium anthraquinone-2-sulphonate initiatior. The concentration of HEMA and PEG-DMA was 30 %, and their ratio was varied to obtain gels with different crosslinking density. It was found, that increasing the amount of the crosslinker in the gels, the force of the deformation increased, however the elasticity decreased. The lowest difference was found between the molar ratio of 50% HEMA: 50% PEG-DMA and the 75% HEMA: 25% PEG-DMA gels. Compression strength was strongly influenced on the ratio of the crosslinking agent. The smallest compression strength was found at the lowest amount of PEG-DMA (90% HEMA: 10% PEG-DMA) (0.0475 MPa +/- 0.0117) and the highest value was found at the highest amount of the PEG-DMA (10% HEMA: 90% PEG-DMA) (0.1366 MPa +/- 0.0546). The values of the compression strength at gels with similar composition was not significantly different. On the base of the present investigations the elasticity of the materials could be calculated from the ratio of monomers. It could be an important parameter in the further applications of the gels as a local delivery system in the parodontology.