Photo-Crosslinkable Polymeric Coatings Providing Chemically Versatile Reactive Surfaces on Various Substrates

Abstract

We demonstrate a chemical route to attain simple, clean, scalable, photopatternable, chemically adjustable, and versatile systems to fabricate reactive organic thin films. Their surfaces exhibit effective biocompatibility, controlled reactivity, and processability on various surface types, i.e., photo-crosslinkable polymeric thin films with various functionalities, further applicable for the definition of surface activity for interfacing biological objects. The copolymers were synthesized with three monomers: a poly(ethylene glycol)-containing monomer, a monomer releasing a primary amine upon exposure to UV light, and a monomer bearing cyclic dithiocarbonate or glycidyl groups that are highly reactive with the amine. The resulting copolymers were processed with polar solvents such as water or alcohol for coating and were readily crosslinked under UV light illumination to form a highly stable molecular network, beneficial for defining selective reactive surfaces in a desired region on a variety of organic and inorganic substrates. The designed system was chemically versatile in immobilizing biologically relevant molecules on the surfaces by (i) post-crosslinking modification through the reaction of bovine serum albumin on the remaining surface reactive group with a primary amine in the protein and (ii) pre-crosslinking formulation with reactive gelatin that has the functionality to crosslink in the composite thin film. We further showed that the resulting coating on a glass or polystyrene substrate provided excellent biocompatibility and growth of C2C12 murine myocytes.

Single-Component Hydrophilic Terpolymer Thin Film Systems for Imparting Surface Chemical Versatility on Various Substrates

“…In general, the phalloidin-stained areas on MGN1 or MDN1 are smaller than those on MGN5 or MDN5. The micrographs in the bottom rows (MDN terpolymers) show higher areas of phalloidin staining than those in the top rows (MGN terpolymers), as evidenced by Figure 9 b. Interestingly, our previous work on the ternary blend of MN/MD or MN/MG with fGelMA showed invariably approximately 500 µm 2 /cells [ 35 ], while the current body of investigation shows 1400–2200 µm 2 /cells, depending on the terpolymer systems. These results further confirm that the terpolymer systems, as opposed to the ternary blend system, were able to improve the display of cell adhesive ligands by preserving such functional groups.…”

“…Moreover, the byproducts can be effectively removed by post-exposure immersion in a solvent. Because the major component of these systems is a poly(ethylene glycol)-based unit that can exhibit biocompatibility, the system can be used for fabricating organic thin film that can be used in a 2D extracellular matrix [ 35 ]. To facilitate cell adhesion, a certain amount of fGelMA, which is known to possess cell-adhesive ligands [ 50 ], was mixed with MGN or MDN.…”

“…It should be noted that even when fGelMA was mixed with the same amount of MGN or MDN (100 wt%), the thin films were found to be well-defined without any significant dewetting or phase separation. This was not the case for the ternary systems consisting of the same monomeric units and fGelMA [ 35 ], thereby elucidating the benefits of the single-component system over the multi-component system.…”

“…2-((((2-Nitrobenzyl)oxy)carbonyl)amino)ethyl methacrylate (NBOCAEMA), cyclic dithiocarbonate methylene methacrylate (DTCMMA), 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl]pentanoic acid (CDSTSP), and methacrylate-incorporated fish skin gelatin (fGelMA; the degree of the addition reaction = 0.920) were synthesized through previously reported procedures [ 35 ]. Potassium tert -butoxide (97%), 2-nitrobenzyl alcohol, 1-dodecylamine (>98%), and lithium bromide (>99.0%) were obtained from Alfa Aesar (Ward Hill, MA, USA).…”

“…Thus, as an ideal system to address these issues, a single-component copolymer that bears all functionalities in one chain needs to be achieved. Although many types of polymeric systems, including simple epoxy-, acrylate-, or azlactone-based monomers and copolymers, have been reported [ 17 , 35 , 36 , 37 , 38 ], it is a challenging task, in the single-component polymer, to simultaneously achieve controlled reactivities for crosslinking on many different types of substrates and post-crosslinking surface functionalization under mild conditions in predictable and appreciable manners. Apparently, chemical routes to realize a rationally designed single-component copolymer system satisfying the above-mentioned criteria should lead us to universal thin film systems based on organic/polymeric materials exhibiting multiple chemical functionalities.…”