Laser bonding with ICG-infused chitosan patches: preliminary experiences in suine dura mater and vocal folds

Abstract

Laser bonding is a promising minimally invasive approach, emerging as a valid alternative to conventional suturing techniques. It shows widely demonstrated advantages in wound treatment: immediate closuring effect, minimal inflammatory response and scar formation, reduced healing time. This laser based technique can overcome the difficulties in working through narrow surgical corridors (e.g. the modern "key-hole" surgery as well as the endoscopy setting) or in thin tissues that are impossible to treat with staples and/or stitches. We recently proposed the use of chitosan matrices, stained with conventional chromophores, to be used in laser bonding of vascular tissue. In this work we propose the same procedure to perform laser bonding of vocal folds and dura mater repair. Laser bonding of vocal folds is proposed to avoid the development of adhesions (synechiae), after conventional or CO 2 laser surgery. Laser bonding application in neurosurgery is proposed for the treatment of dural defects being the Cerebro Spinal Fluid leaks still a major issue. Vocal folds and dura mater were harvested from 9-months old porks and used in the experimental sessions within 4 hours after sacrifice. In vocal folds treatment, an IdocyanineGreen-infused chitosan patch was applied onto the anterior commissure, while the dura mater was previously incised and then bonded. A diode laser emitting at 810 nm, equipped with a 600 µm diameter optical fiber was used to weld the patch onto the tissue, by delivering single laser spots to induce local patch/tissue adhesion. The result is an immediate adhesion of the patch to the tissue. Standard histology was performed, in order to study the induced photothermal effect at the bonding sites. This preliminary experimental activity shows the advantages of the proposed technique in respect to standard surgery: simplification of the procedure; decreased foreign-body reaction; reduced inflammatory response; reduced operating times and better handling in depth. ; phone 0039 055-522 5337; fax 0039 055 522 5305

Mild and Effective Polymerization of Dopamine on Keratin Films for Innovative Photoactivable and Biocompatible Coated Materials

“…Single spot irradiation with ms‐long optical pulses through a fiber‐optic delivery system triggered melting of the corneal tissue and KerAzAPD red films. The tensile strength was tested by using surgical tweezers and survived a load in excess of several load factor (g), in line with that found with capsular tissue or chitosan hydrogels doped with indocyanine green or plasmonic particles and sufficient to withstand subsequent manipulation with surgical tools for the preparation of histological sections. Figure displays photographs taken through a surgical microscope (panels A and B) and histological sections across representative irradiated spots (panels C, D, and E).…”

“…Figure displays photographs taken through a surgical microscope (panels A and B) and histological sections across representative irradiated spots (panels C, D, and E). On visual inspection, the onset of a photothermal effect was evident as a bleaching of the patch sample (Figure A), which may result from the interplay of different factors, such as an alteration of the organic dye and explosive boiling within the keratin sheet. The histological analysis corroborated the adhesive effect, the onset of explosive boiling within the KerAzAPD red films as well as an alteration of the corneal tissue consistent with its thermal denaturation.…”

Characterization and Ex Vivo Application of Indocyanine Green Chitosan Patches in Dura Mater Laser Bonding

“…Dural substitutes and sealants allow lowering the overall incidence, but they are expensive and associated with various complications, both acute and chronic. Consequently, a standardization of dura mater reconstruction is still lacking [ 21 ].…”

“…After evaporation of the solvent, the samples were neutralized with 1 M NaOH solution (Sigma-Aldrich, Milano, Italy, product code S8045) and finally washed out with abundant water. The as-obtained patches (0.8 cm diameter, about 40-μm thickness) were carefully detached from the moulds and stored until their use in the experiments [ 21 ]. The UV–Vis absorption spectra of the ICG-loaded patches were measured at 25 °C and 4 °C temperatures and different times after their preparation to evaluate the stability and the optical properties of the material over time [ 21 ].…”

“…In previous studies, we published a preliminary ex vivo test of vocal fold laser bonding through ICG-infused chitosan patches, evidencing the feasibility of the laser-assisted procedure [ 21 ]. Subsequently, we proposed a new laser-based approach to bonding biological tissues: different biopolymeric matrices were designed and prepared in the form of a patch covering the surgical wound [ 12 , 22 , 23 ].…”