Publications

Herein, an innovative self- and pressure-adhesive biomedical implant was developed. Tissue adhesion was achieved with a thermosensitive hydrogel based on poly-(N-isopropylacrylamide-co-acrylamide), PNIPAAm-co-PAAm, grafted on a substrate composed of knitted fibers of isotactic polypropylene mesh (PP), used as surgical mesh implants. The in vitro studies, carried out with porcine skin, showed an important role of the inclusion of acrylamide-based comonomer (AAm) in the thermosensitive hydrogel PNIPAAm matrix. The bonding, peeling, and shearing energies obtained for PNIPAAm-co-PAAm increased exponentially up to three, two, and six times, respectively, compared to the gel without AAm. The physisorption and mechanical interlocking mechanisms are responsible for such improvement due to the simultaneous creation of hydrophobic and hydrophilic interactions of the thermosensitive hydrogel at temperatures higher than the lower critical solution temperature (LCST), with the porcine tissue. In addition, our bioadhesives present excellent interfacial toughness (similar to 100 J/m(2)) when compared to commercial bioglues (similar to 50 J/m(2) or lower). The results obtained represent a very promising adhesive material that is extensible to other medical devices that require atraumatic fixation to avoid chronic pain related to other fixation approaches.

JTD Keywords: Bioadhesive, Complications, Hernia-repair, Interface adhesion, Mechanicalinterlocking, Physisorption, Poly(n-isopropylacrylamide), Polypropylene mesh, Surgicalmesh, Thermosensitive hydrogel

This work presents a novel nanoparticle-based thermosensor implant able to reveal the precise temperature variations along the polymer filaments, as it contracts and expands due to changes in the macroscale local temperature. The multimodal device is able to trace the position and the temperature of a polypropylene mesh, employed in abdominal hernia repair, by combining plasmon resonance and Raman spectroscopy with hydrogel responsive system. The novelty relies on the attachment of the biocompatible nanoparticles, based on gold stabilized by a chitosan-shell, already charged with the Raman reporter (RaR) molecules, to the robust prosthesis, without the need of chemical linkers. The SERS enhanced effect observed is potentiated by the presence of a quite thick layer of the copolymer (poly(N-isopropylacrylamide)-co-poly(acrylamide)) hydrogel. At temperatures above the LCST of PNIPAAm-co-PAAm, the water molecules are expulsed and the hydrogel layer contracts, leaving the RaR molecules more accessible to the Raman source. In vitro studies with fibroblast cells reveal that the functionalized surgical mesh is biocompatible and no toxic substances are leached in the medium. The mesh sensor opens new frontiers to semi-invasive diagnosis and infection prevention in hernia repair by using SERS spectroscopy. It also offers new possibilities to the functionalization of other healthcare products.© 2023 Wiley-VCH GmbH.

JTD Keywords: adhesion, blends, chitosan, gold nanoparticles, poly(n-isopropylacrylamide), polypropylene mesh, polypropylene meshes, repair, scattering, silver, surgical implants, thermosensitive hydrogels, toxicity, Chitosan, Gold nanoparticles, Polypropylene meshes, Surgical implants, Thermosensitive hydrogels

Isotactic polypropylene (i-PP) nonabsorbable surgical meshes are modified by incorporating a conducting polymer (CP) layer to detect the adhesion and growth of bacteria by sensing the oxidation of nicotinamide adenine dinucleotide (NADH), a metabolite produced by the respiration reactions of such microorganisms, to NAD+. A three-step process is used for such incorporation: (1) treat pristine meshes with low-pressure O2 plasma; (2) functionalize the surface with CP nanoparticles; and (3) coat with a homogeneous layer of electropolymerized CP using the nanoparticles introduced in (2) as polymerization nuclei. The modified meshes are stable and easy to handle and also show good electrochemical response. The detection by cyclic voltammetry of NADH within the interval of concentrations reported for bacterial cultures is demonstrated for the two modified meshes. Furthermore, Staphylococcus aureus and both biofilm-positive (B+) and biofilm-negative (B-) Escherichia coli cultures are used to prove real-time monitoring of NADH coming from aerobic respiration reactions. The proposed strategy, which offers a simple and innovative process for incorporating a sensor for the electrochemical detection of bacteria metabolism to currently existing surgical meshes, holds considerable promise for the future development of a new generation of smart biomedical devices to fight against post-operative bacterial infections.

JTD Keywords: adhesion, bacteria metabolism, behavior, biocompatibility, conducting polymer, electrochemical sensor, hernia repair, in-vivo, liquid, nadh detection, plasma treatment, prevention, reinforcement, sensor, smart meshes, Bacteria metabolism, Polypropylene mesh, Smart meshes

Herein, a facile approach toward transforming a 2D polypropylene flexible mesh material into a 4D dynamic system is presented. The versatile platform, composed by a substrate of knitted fibers of isotactic polypropylene (iPP) mesh and a coating of thermosensitive poly(N‐isopropylacrylamide‐co‐N,N’‐methylene bis(acrylamide) (PNIPAAm‐co‐MBA) hydrogel, covalently bonded to the mesh surface, after cold‐plasma surface treatment and radical polymerization, is intended to undergo variations in its geometry via its reversible folding/unfolding behavior. The study is the first to trace the 3D movement of a flat surgical mesh, intended to repair hernia defects, under temperature and humidity control. An infrared thermographic camera and an optical microscope are used to evaluate the macroscopic and microscopic structure stimulus response. The presence of the PP substrate and the distribution of the gel surrounding the PP threads, affect both the PNIPAAM gel expansion/contraction as well as the time of folding/unfolding response. Furthermore, PP‐g‐PNIPAAm meshes show an increase in the bursting strength of ≈16% with respect to the uncoated mesh, offering a strongest and adaptable system for its future implantation in human body. The findings reported offer unprecedented application possibilities in the biomedical field.

JTD Keywords: Dynamic devices, Polypropylene meshes, Surgical implants, Thermosensitive hydrogels