Hydrogels are interesting as wound dressing for burn wounds to maintain a moist environment. Especially gelatin and alginate based wound dressings show strong potential. Both polymers are modified by introducing photocrosslinkable functionalities and combined to hydrogel films (gel‐MA/alg‐MA). In one protocol gel‐MA films are incubated in alg‐MA solutions and crosslinked afterward into double networks. Another protocol involves blending both and subsequent photocrosslinking. The introduction of alginate into the gelatin matrix results in phase separation with polysaccharide microdomains in a protein matrix. Addition of alg(‐MA) to gel‐MA leads to an increased swelling compared to 100% gelatin and similar to the commercial Aquacel Ag dressing. In vitro tests show better cell adhesion for films which have a lower alginate content and also have superior mechanical properties. The hydrogel dressings exhibit good biocompatibility with adaptable cell attachment properties. An adequate gelatin‐alginate ratio should allow application of the materials as wound dressings for several days without tissue ingrowth.

Polysaccharides, and especially alginate, can be useful for self-healing of cracks in concrete. Instead of weak electrostatic bonds present within calcium alginate, covalent bonds, by methacrylation of the polysaccharides, will result in mechanically stronger superabsorbent polymers (SAPs). These methacrylated alginate chains as backbone are combined with two acrylic monomers in a varying molar fraction. These SAPs show a moisture uptake capacity up to 110% their own weight at a relative humidity of 95%, with a negligible hysteresis. The swelling capacity increased (up to 246 times its own weight) with a decreasing acrylic acid/2 acrylamido-2-methylpropane sulfonic acid ratio. The SAPs also showed a thermal stability up to 200°C. Interestingly, the SAP composed of alginate and acrylic acid exerted a very limited decrease in compressive strength (up to 7% with addition of 1wt% SAP) rendering this material interesting for the envisaged self-healing application.

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In the present contribution, we report the MADIX/RAFT polymerization for the synthesis of thermoresponsive homo and statistical copolymers of N-vinylcaprolactam (NVCL) and N-vinylpyrrolidone (NVP). The conditions for the polymerization of NVP were optimized using an automated parallel synthesizer and these optimal conditions were applied for preparing copolymers with systematical variation in composition. The cloud point temperatures (T-CP's) of aqueous solutions of PNVCL and P(NVCL-stat-NVP)'s (CP1-CP5) were found to be tuneable between 40 degrees C and >95 degrees C at 5 mg mL(-1). Next, stable colloidal solutions of AuNPs coated with PNVCL and CP1-CP5 were obtained via an exchange reaction of pre-synthesized citrate stabilized AuNPs with PNVCL and CP1-CP5 by a direct 'grafting to' approach. The maximum absorbance wavelength (lambda(max)) of the surface plasmon resonance (SPR) band and size of all the thermoresponsive polymer coated AuNPs were found to be almost unchanged up to 65 degrees C (above the T-CP of PNVCL and CP5) in MilliQ water which is presumably due to electrostatic stabilization of the AuNPs by residual citrate groups on the surface. However, in 0.1 M NaCl aqueous solution the lambda(max) of the thermoresponsive AuNPs were red shifted when heated up to 65 degrees C which is attributed to the screening of the citrate negative charges on the surface of AuNPs that suppress electrostatic stabilization enabling T-induced aggregation leading to a shift in the SPR band. These thermoresponsive AuNPs may find applications as colorimetric temperature and/or salt sensors

The protection of primary amines available in proteins holds great potential to introduce a plethora of diverse functionalities along the protein backbone (e.g., via its carboxylic acid or alcohol moieties) while circumventing the crosslinking issue using conventional approaches. This paper reports on a straightforward and efficient proof-of-concept including the chemoselective N-tert-butyloxycarbonylation of the primary amines in the protein gelatin (gel-NH-BOC), followed by introducing crosslinkable methacrylamide moieties. The reaction is performed successfully under relatively mild conditions (50 °C). Following selective protein functionalization, the deprotection is realized by adding a catalytic amount of an aqueous hydrogen chloride solution. The present communication illustrates the occurrence of a straightforward and selective deprotection procedure, which is typically required to circumvent the occurrence of acidic hydrolysis of the protein backbone. The results hold promise for a large range of biomedical applications in which the presence of primary amines is essential for preserving the biological activity.

Gelatin is used widely in the biomedical field, among other for wound healing. Given its upper critical solution temperature, crosslinking is required. To this end, gelatin is chemically modified with different photo-crosslinkable moieties with low (32-34%) and high (63-65%) degree of substitution (DS): gelatin-methacrylamide (gel-MA) and gelatin-acrylamide (gel-AA) and gelatin-pentenamide (gel-PE). Next to the more researched gel-MA, it is especially interesting and novel to compare with other gelatin-derived compounds for the application of wound healing. An additional comparison is made with commercial dressings. The DS is directly proportional to the mechanical characteristics and inversely proportional to the swelling capacity. Gel-PE shows weaker mechanical properties (G′ < 15 kPa) than gel-AA and gel-MA (G′ < 39 and 45 kPa, respectively). All derivatives are predominantly elastic (recovery indices of 89-94%). Gel-AA and gel-MA show excellent biocompatibility, whereas gel-PE shows a significantly lower initial biocompatibility, evolving positively toward day 7. Overall, gel-MA shows to have the most potential to be applied as wound dressing. Future blending with gel-AA to improve the curing kinetics can lead to dressings able to compete with current commercial dressings.

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