pH-Dependent Stability of Self-Assembled Monolayers on Gold

摘要: Self-assembled monolayers (SAMs) have attracted considerable attention because of their wide applications to biosensors, optoelectronic devices, control wettability and biocompatibility, corrosion resistance, etc. Among various types SAMs formed on numerous kinds substrates, the alkanethiols gold extensively been studied, primarily it is relatively easy simple form well-organized compared with methods used for other substrates. In addition, surface enables us effortlessly use analytical techniques, including plasmon resonace spectroscopy, quartz crystal microbalance, reflection absorption infrared spectroscopy ellisometry, in mechanistic studies potential SAMs. Especially, long-chain ω-functional groups, such as OH, COOH, NH2, a great deal interest, these would yield more interesting properties surfaces through post-modification reactions, nucleophilic substitution, esterification, acylation, addition own chemical properties. For example, modifications OH-, COOH-, NH2-terminated attachment biopolymers, oligonucleotides peptides, onto surfaces, which essential step application biotechnology. Since post-modifications are performed under conditions temperature, pH solvents, stability against potentially destructive important wider well design reactions. The air-stability alkanethiolbased was studied one week several months. Their longterm also investigated biological media, biomaterials platform, necessitate prolonged exposure media. Recently, effect storage conditions, air, N2, ethanol, phosphate buffer H2O, mixed poly(ethylene oxide)-thiol ensure long-term preservation biosensing property. SAMs, dependency aqueous solutions be established, since modification reactions at values. As related work, dissociation phenomena thiolate ligands from cadmium chalcogenide nanocrystals examined by varying this we pHdependent alkanethiol functional groups terminals, order give basic but crucial information SAMbased CH3, or NH2 group were prepared gold, values 1 14 measuring changes ellipsometric thickness. preparation clean substrate immersed 20 h each solution HS-(CH2)15-CH3, HS-(CH2)16-OH, HS-(CH2)15-COOH, HS-(CH2)16-NH2. characterized FTIR (Figure 1). Figure 1a shows IR peaks