Waste to Wealth Approach: Improved Antimicrobial Properties in Bioactive Hydrogels through Humic Substance-Gelatin Chemical Conjugation

Exploring opportunities for biowaste valorization, herein,humicsubstances (HS) were combined with gelatin, a hydrophilic biocompatibleand bioavailable polymer, to obtain 3D hydrogels. Hybrid gels (GelHS) were prepared at different HS contents, exploiting physical orchemical cross-linking, through 1-ethyl-(3-3-dimethylaminopropyl)-carbodiimide(EDC) chemistry, between HS and gelatin. Physicochemical featureswere assessed through rheological measurements, X-ray diffraction,attenuated total reflectance (ATR) spectroscopy, nuclear magneticresonance (NMR) spectroscopy, and scanning electron microscopy (SEM).ATR and NMR spectroscopies suggested the formation of an amide bondbetween HS and Gel via EDC chemistry. In addition, antioxidant andantimicrobial features toward both Gram(-) and Gram-(+) strainswere evaluated. HS confers great antioxidant and widespread antibioticperformance to the whole gel. Furthermore, the chemical cross-linkingaffects the viscoelastic behavior, crystalline structures, water uptake,and functional performance and produces a marked improvement of biocideaction.

Automated summary

In this study, humic substances (HS) were combined with gelatin to produce 3D hydrogels. Hybrid gels (GelHS) were prepared by physical or chemical cross-linking. The physicochemical features of the gels were evaluated using various techniques, and the results showed the formation of an amide bond between HS and gelatin via EDC chemistry. The gels exhibited antioxidant and antimicrobial properties, and the chemical cross-linking process improved their viscoelastic behavior, crystalline structures, water uptake, and biocidal activity.