Surface Modification of Functional Self-Assembled Monolayers on 316L Stainless Steel via Lipase Catalysis

Abstract

Lipase catalyzed esterification of therapeutic drugs to functional self-assembled monolayers (SAMs) on 316L stainless steel (SS) after assembly has been demonstrated. SAMs of 16-mercaptohexadecanoic acid (-COOH SAM) and 11-mercapto-1-undecanol (-OH SAM) were formed on 316L SS, and lipase catalysis was used to attach therapeutic drugs, perphenazine and ibuprofen, respectively, on these SAMs. The reaction was carried out in toluene at 60 degrees C for 5 h using Novozyme-435 as the biocatalyst. The FTIR spectra after surface modification of -OH SAMs showed the presence of the C=O stretching bands at 1745 cm(-1), which was absent in the FTIR spectra of -OH SAMs. Similarly, the FTIR spectra after the reaction of the -COOH SAM with perphenazine showed two peaks in the carbonyl region, a peak at 1764 cm(-1), which is the representative peak for the C=O stretching for esters. The second peak at 1681 cm(-1) is assigned to the C=O stretching of the remaining unreacted terminal COOH. XPS spectra after lipase catalysis with ibuprofen showed a photoelectron peak evolving at 288.5 eV which arises from the carbon (C=O) of the carboxylic acid of the drug (ibuprofen). Similarly for -COOH SAMs, after esterifiation we see a small, photoelectron peak evolving at 286.5 eV which corresponds to the C in the methylene groups adjacent to the oxygen (C-O), which should evolve only after the esterification of perphenazine with the -COOH SAM. Thus, lipase catalysis provides an alternate synthetic methodology for surface modification of functional SAMs after assembly.

Coronary stents: A materials perspective

“…Hence, research should be carried out in designing and developing new polymer materials and should include essential features like hemocompatibility, hydrophobicity, anti-inflammatory, conformability to the stent surface, flaking resistance, sterilizability, and biodegradability. Other approaches such No polymer material will be present once the process is finished Preferred category of polymers Biopolymers Minimal inflammatory and hypersensitive reactions as nanoporous coatings and using self-assembled monolayers [265][266][267][268] for drug delivery also have potential applications in the next generation of stents.…”

Grafting of nanoporous alumina membranes and films with organic acids

“…In addition, we observed two photoelectron peaks evolving at 288.5 and 286.2 eV, which arose from the 'C' (C O) and 'C' (C-O), respectively, of the organic acids. 15 These peaks remained clearly distinct after the samples were kept at ambient conditions for 30 days. Figure 3 gives the raw and fitted XPS spectra of Al 2p on ungrafted and organic-acid-grafted alumina membranes.…”

Long‐term stability of self‐assembled monolayers on electropolished L605 cobalt chromium alloy for stent applications

“…[16][17][18][19][20][21][22][23] However, electropolished (EP) metals such as 316L stainless steel (SS) or L605 cobalt chromium alloy (CoCr) have different surface chemistry than that of the native or mechanically polished surfaces. Several studies report increased concentrations of oxygen and metallic elements compared to the as-received metal surface, specifically increased chromium and hydroxyl group concentrations and decreased iron concentration.…”