Degradable Amine-Reactive Coatings Fabricated by the Covalent Layer-by-Layer Assembly of Poly(2-vinyl-4,4-dimethylazlactone) with Degradable Polyamine Building Blocks

Abstract

We report the fabrication of reactive and degradable cross-linked polymer multilayers by the reactive/covalent layer-by-layer assembly of a non-degradable azlactone-functionalized polymer [poly(2-vinyl-4,4-dimethylazlactone), PVDMA] with hydrolytically or enzymatically degradable polyamine building blocks. Fabrication of multilayers using PVDMA and a hydrolytically degradable poly(β-amino ester) (PBAE) containing primary amine side chains yielded multilayers (∼100 nm thick) that degraded over ∼12 days in physiologically relevant media. Physicochemical characterization and studies on stable films fabricated using PVDMA and an analogous non-degradable poly(amidoamine) suggested that erosion occurred by chemical hydrolysis of backbone esters in the PBAE components of these assemblies. These degradable assemblies also contained residual amine-reactive azlactone functionality that could be used to impart new functionality to the coatings post-fabrication. Cross-linked multilayers fabricated using PVDMA and the enzymatically degradable polymer poly(l-lysine) were structurally stable for prolonged periods in physiological media, but degraded over ∼24 h when the enzyme trypsin was added. Past studies demonstrate that multilayers fabricated using PVDMA and non-degradable polyamines [e.g., poly(ethylenimine)] enable the design and patterning of useful nano/biointerfaces and other materials that are structurally stable in physiological media. The introduction of degradable functionality into PVDMA-based multilayers creates opportunities to exploit the reactivity of azlactone groups for the design of reactive materials and functional coatings that degrade or erode in environments that are relevant in biomedical, biotechnological, and environmental contexts. This "degradable building block" strategy should be general; we anticipate that this approach can also be extended to the design of amine-reactive multilayers that degrade upon exposure to specific chemical triggers, selective enzymes, or contact with cells by judicious design of the degradable polyamine building blocks used to fabricate the coatings.

Host-Guest Chemistry in Layer-by-Layer Assemblies Containing Calix[n]arenes and Cucurbit[n]urils: A Review

“…LPG sensors coated with s-CA[n] films show a response to vapors of various VOCs, including chloroform, benzene, toluene, and acetone. Sensors coated with s-CA [4] film exhibit greater responses than those coated with s-CA [8] [41]. DR is known to react with substituents such as carboxylate and sulfonate groups to form covalent bonds under UV light irradiation [42].…”

“…The same group used amphiphilic s-CA[n]s as molecular containers for immobilizing small molecules in LbL films [44]. To achieve this goal, s-CA [8] bearing C 12 alkyl chains were alternately deposited with PDDA in the presence of organic dyes such as p-hydroxyazobenzene, methyl yellow, and Sudan III. The LbL films thus-prepared showed absorption bands associated with the dyes, suggesting that the dyes were incorporated into the cavity of s-CA [8] in the films.…”

“…To achieve this goal, s-CA [8] bearing C 12 alkyl chains were alternately deposited with PDDA in the presence of organic dyes such as p-hydroxyazobenzene, methyl yellow, and Sudan III. The LbL films thus-prepared showed absorption bands associated with the dyes, suggesting that the dyes were incorporated into the cavity of s-CA [8] in the films. The results suggest the usefulness of s-CA[n]s as carriers for the immobilization of small molecules in LbL films.…”

“…Tieke and coworkers have systematically studied the permeability of CA[n]-containing LbL films deposited on the surfaces of porous polymer supports made of poly(acrylonitrile) and poly(ethylene terephthalate) [44][45][46][47][48][49]. s-CA [4], s-CA [6], and s-CA [8] were successfully built into LbL films by combining polycations, such as poly(vinyl amine) (PVA) and poly(allylamine hydrochloride). The deposition behavior of s-CA[n]s depends on the ring size of s-CA[n]s; a higher amount of s-CA [8] than s-CA [4] and s-CA [6] is deposited in the LbL film, depending on the number of the binding sites, that is, the sulfonate residues, in the s-CA[n]s.…”

“…LbL deposition affords stratified multilayer architectures on the surface. A variety of interactions, such as hydrogen bonds [3,4], host-guest complexations [5], charge-transfer (CT) interactions [6], DNA hybridization [7], covalent bonds [8], and protein-ligand affinity [9] are available as the driving forces for the construction of films. Consequently, both synthetic polymers and biomaterials, which include proteins [10,11], polysaccharides [12,13], and DNA [14,15], are often used as components of LbL films.…”