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The interaction between surfaces and biological elements, in particular, proteins is critical for the performance of biomaterials and biosensors. This interaction can be controlled by modifying the surface in a process known as biofunctionalization. In this work, the enzyme lactate dehydrogenase (LDH) is used to study the stability of the interaction between a functional protein and amine-functionalized surfaces. Two different functionalization procedures were compared: Activated Vapor Silanization (AVS) and Immersion Silanization (IS). Adsorption kinetics is shown to follow the Langmuir model for AVS-functionalized samples, while IS-functionalized samples show a certain instability if immersed in an aqueous medium for several hours. In turn, the enzymatic activity of LDH is preserved for longer times by using glutaraldehyde as crosslinker between the AVS biofunctional surface and the enzyme. [ABSTRACT FROM AUTHOR]

Atomic force microscopy (AFM) is a powerful tool in Biology due to the possibility of identifying and locating single molecules at a subnanometer scale. Performing these experiments requires the usage of functionalized AFM tips to which sensing molecules can be attached. In this work the possibility of functionalizing AFM cantilevers and tips using the activated vapour silanization (AVS) process is explored. Functionalized thin films are deposited on commercial silicon nitride chips and their presence is assessed by measuring the variation in the resonance frequency of the cantilever. Subsequently, the presence and functionality of the films is studied through the covalent immobilization of a fluorescein-derived molecule to the amine reactive groups on the surface. With regard to its sensing ability, the functionalized tips are shown to sustain repetitive interactions with a model graphite substrate (HOPG) under relatively harsh conditions, while no apparent damage is observed in the tip. It is also found that the substrate-tip interaction may be modified by covalently attaching a molecule to the latter. Consequently, AVS functionalized AFM tips are found to be robust and reliable candidates for their use in the affinity (or chemical) atomic force microscopy (AF-AFM) mode. Unlabelled Image • Atomic force microscopy (AFM) cantilevers and tips were functionalized by activated vapor silanization (AVS). • The deposition of the functionalized layer was assessed through variations in the resonance frequency of the cantilever. • The reactivity of the amine groups in the functionalized layer was checked by forming covalent bonds with a fluorophore. • The stability of the functionalized film upon repeated interactions with a model HOPG substrate was established. • AVS functionalized AFM tips appear as promising candidates for their usage in affinity atomic force microscopy experiments. [ABSTRACT FROM AUTHOR]

Titanium (Ti) and titanium alloys are among the most-commonly used metallic materials for implantation in the human body for the purpose of replacing hard tissue. Although Ti and its alloys are widely used for such an aim, in implants of a long duration they exhibit some shortcomings due to the loosening of the very implant. This phenomenon is highly dependent on the interaction between the organic tissues and the surface of the implant. In this study, the authors introduce a surface treatment technique for functionalization of the surface of Ti-6Al-4V alloy with amino groups that could help to control this interaction. The functionalized layer was deposited by activated vapor silanization (AVS), which has been proven as a reliable and robust technique with other materials. The resulting biofunctional layers were characterized by atomic force microscopy and fluorescence microscopy, with the optimal conditions for the deposition of a homogeneous film with a high density of amino groups being determined. Additionally, the non-toxic nature and stability of the biofunctional layer were confirmed by cell culturing. The results show the formation of a homogeneous biofunctional amine layer on Ti-6Al-4V alloy that may be used as a platform for the subsequent covalent immobilization of proteins or other biomolecules. [ABSTRACT FROM AUTHOR]

Activated vapor silanization (AVS) is used to functionalize silicon surfaces through deposition of amine-containing thin films. AVS combines vapor silanization and chemical vapor deposition techniques and allows the properties of the functionalized layers (thickness, amine concentration and topography) to be controlled by tuning the deposition conditions. An accurate characterization is performed to correlate the deposition conditions and functional-film properties. In particular, it is shown that smooth surfaces with a sufficient surface density of amine groups may be obtained with this technique. These surfaces are suitable for the study of proteins with atomic force microscopy. [ABSTRACT FROM AUTHOR]