Manipulating mechanical properties of PEG-based hydrogel nanocomposite: A potential versatile bio-adhesive for the suture-less repair of tissue

Multifunctional bio-adhesives with tunable mechanical properties are obtained by controlling the orientation of anisotropic particles in a blend of fast-curing hydrogel with an imposed capillary flow. The suspensions' microstructural evolution was monitored by the small-angle light scattering (SALS) method during flow up to the critical Péclet number (Pe≈1) necessary for particle orientation and hydrogel crosslinking. The multifunctional bio-adhesives were obtained by combining flow and UV light exposure for rapid photo-curing of PEGDA medium and freezing titania rods' ordered microstructures. Blending the low- and high-molecular weight of PEGDA polymer improved the mechanical properties of the final hydrogel. All the hydrogel samples were non-cytotoxic up to 72 h after cell culturing. The system shows rapid blood hemostasis and promotes adhesive and cohesive strength matching targeted tissue properties with an applicating methodology compatible with surgical conditions. The developed SALS approach to optimize nanoparticles' microstructures in bio-adhesive applies to virtually any optically transparent nanocomposite and any type of anisotropic nanoparticles. As such, this method enables rational design of bio-adhesives with enhanced anisotropic mechanical properties which can be tailored to potentially any type of tissue.

Functional modification of mussel adhesive protein to control solubility and adhesion property

Marine mussels produce strong underwater adhesives called mussel adhesive proteins (MAPs) that can adhere to a variety of surfaces under physiological conditions. Thus, MAPs have been investigated as a potentially sustainable alternative to conventional petrochemical-based adhesives. Recombinant MAPs would be promising for large-scale production and commercialization; however, MAPs are intrinsically adhesive, aggregative, and insoluble in water. In this study, we have developed a solubilization method for the control of MAP adhesion by fusion protein technique. Foot protein 1 (Fp1), a kind of MAP, was fused with the highly water-soluble protein, which is the C-terminal domain of ice-nucleation protein K (InaKC), separated by a protease cleaving site. The fusion protein exhibited low adhesion but high solubility and stability. Notably, Fp1 recovered its adhesive property after removal from the InaKC moiety by protease cleaving, which was evaluated and confirmed by the agglomeration of magnetite particles in water. The ability to control adhesion and agglomeration makes MAPs favorable prospects for bio-based adhesives.

'Waterproofing layers' for urethrocutaneous fistula repair after hypospadias surgery: evidence synthesis with systematic review and meta-analysis

OBJECTIVE

To summarize the available evidence and to quantitatively evaluate the global results of different waterproofing layers in substantiating the UCF repair.

MATERIAL AND METHODS

After defining the study protocol, the review was conducted according to the PRISMA guidelines by a team comprising experts in hypospadiology, systematic reviews and meta-analysis, epidemiology, biostatistics and data science. Studies published from 2000 onwards, reporting on the results of UCF closure after hypospadias repair were searched for on PUBMED, Embase and Google Scholar. Study quality was assessed using Joanna Briggs Checklist (JBI) critical appraisal tool. The results with different techniques were compared with the two samples independent proportions test with the help of Microsoft Excel, MedCalc software and an online calculator.

RESULTS

Seventy-three studies were shortlisted for the synthesis; the final analysis included 2886 patients (71 studies) with UCF repair failure in 539. A summary of various dimensions involved with the UCF repair has been generated including time gap after last surgery, stent-vs-no stent, supra-pubic catheterization, suture material, suturing technique, associated anomalies, complications, etc. The success rates associated with different techniques were calculated and compared: simple catheterization (100%), simple primary closure (73.2%), dartos (78.8%), double dartos flaps (81%), scrotal flaps (94.6%), tunica vaginalis (94.3%), PATIO repair (93.5%), biomaterials or dermal substitutes (92%), biocompatible adhesives (56.5%) and skin-based flaps (54.5%). Several techniques were identified as solitary publications and discussed.

CONCLUSIONS

Tunica vaginalis and scrotal flaps offer the best results after UCF closure in the synthesis. However, it is not possible to label any technique as ideal or perfect. Almost all popular waterproofing layers have depicted absolute (100%) success sometimes. There are a vast number of other factors (patient's local anatomy, surgeon's expertise and technical perspectives) which influence the final outcome.