Improving the antibacterial properties of polypropylene patches used in hernia surgery with amine functional polymer coatings

Polypropylene (PP) patches are widely preferred in hernia repair surgeries due to their mechanical strength, flexibility and ease of use. However, the non-hydrophilic and non-biologically active nature of these patches predisposes to bacterial adhesion and increases the risk of postoperative infection. In this study, a functionalisation strategy was developed with amine-functional polymer coatings to introduce positively charged functional groups on the PP patch surface. The selected polymer, poly[(dimethylaminoethyl methacrylate)-co-(ethyleneglycol dimethacrylate)] (poly-DMAEMA-co-EGDMA), can disrupt membrane integrity and cause bacterial death by electrostatic interaction with bacterial cell membranes thanks to the amine groups it contains. By using EGDMA as a cross-linker, it was aimed to increase the stability of the coating and to provide long-term antibacterial effect. In order to enhance the antibacterial properties of PP patches, sequential surface modification was carried out in three main steps: (i) introduction of oxygen-containing functional groups to the surface by UV/ozone treatment, (ii) formation of reactive surfaces by silanation with 3-(Trimethoxysilyl)propyl acrylate (TMSPA) and (iii) immobilisation of positively charged quaternary amine groups with poly[(dimethylaminoethyl methacrylate)-co-(ethylene glycol dimethacrylate)] (poly-DMAEMA-co-EGDMA) polymer. The characterisation studies showed that the surface modifications were successful. X-ray photoelectron spectroscopy (XPS) analyses revealed elemental and chemical composition changes confirming each treatment step and N 1s peaks indicated the presence of quaternary amine groups. Fourier transform infrared spectroscopy (FTIR) results also supported these changes at the molecular level. Scanning electron microscopy (SEM) and optical microscope analyses showed that a homogeneous coating layer was formed on the surface with preservation of the fiber structure and partial closure of the pores. Water contact angle (WCA) measurements revealed that the modification steps significantly changed the surface wettability: the untreated PP surface was hydrophobic (117.82°), whereas after quaternary amine coating it acquired a moderately hydrophilic character (63.51°). Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) data showed that the modifications did not adversely affect the thermal stability of the PP patch, on the contrary, the quaternary amine coating improved the heat resistance Antibacterial activity was tested against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria using agar diffusion method. The modified patches exhibited effective antibacterial performance against both bacterial species by forming distinct inhibition zones. The findings show that the developed surface modification strategy successfully enhanced the antibacterial properties of PP patches while preserving their structural, thermal and morphological properties. This approach offers a simple, reproducible and industrially applicable method for the fabrication of biocompatible and antibacterial surgical patches and holds promise for the next generation of patch designs that have the potential to improve clinical success in hernia repair surgeries by reducing the risk of infection and promote patient recovery.