RESUMO
The long-term stability and γ-sterilisability of bioactive layers is the precondition for the application of implants. Thus, aging processes of a microwave deposited, plasma polymerized allylamine nanofilm (PPAAm) with positively charged amino groups were evaluated concerning physicochemical characteristics and cell adhesion capacity over the course of one year. XPS, FT-IR, surface free energy, and water contact angle measurements elucidated not only the oxidation of the PPAAm film due to atmospheric oxygen reacting with surface free radicals but also the influence of atmospheric moisture during sample storage in ambient air. Surprisingly, within 7 days 70% of the primary amino groups are lost and mostly converted into amides. A positive zeta-potential was verified for half a year and longer. Increasing polar surface groups and a water contact angle shift from 60° to 40° are further indications of altered surface properties. Nevertheless, MG-63 human osteoblastic cells adhered and spread out considerably on aged and additionally γ-sterilized PPAAm layers deposited on polished titanium alloys (Ti-6Al-4V_P). These cell-relevant characteristics were highly significant over the whole period of one year and may not be related to the existence of primary amino groups. Rather, the oxidation products, the chemical amide group, that is, seem to support the attachment of osteoblasts at all times up to one year.
Assuntos
Alilamina , Membranas Artificiais , Nanoestruturas/química , Osteoblastos/metabolismo , Gases em Plasma , Titânio , Ligas , Alilamina/química , Alilamina/farmacologia , Adesão Celular/efeitos dos fármacos , Linhagem Celular , Materiais Revestidos Biocompatíveis/química , Materiais Revestidos Biocompatíveis/farmacologia , Humanos , Teste de Materiais , Osteoblastos/citologia , Oxirredução , Fatores de Tempo , Titânio/química , Titânio/farmacologiaRESUMO
The recent availability of thermoelectrically cooled pulsed and continuous wave quantum and inter-band cascade lasers in the mid-infrared spectral region has led to significant improvements and new developments in chemical sensing techniques using in-situ laser absorption spectroscopy for plasma diagnostic purposes. The aim of this article is therefore two-fold: (i) to summarize the challenges which arise in the application of quantum cascade lasers in such environments, and, (ii) to provide an overview of recent spectroscopic results (encompassing cavity enhanced methods) obtained in different kinds of plasma used in both research and industry.
