Characterization and ex vivo application of indocyanine green chitosan patches in dura mater laser bonding

Dura mater repair represents a final and crucial step in neurosurgery: an inadequate dural reconstruction determines dreadful consequences that significantly increase morbidity and mortality rates. Different dural substitutes have been used with suboptimal results. To overcome this issue, in previous studies, we proposed a laser-based approach to the bonding of porcine dura mater, evidencing the feasibility of the laser-assisted procedure. In this work, we present the optimization of this approach in ex vivo experiments performed on porcine dura mater. An 810-nm continuous-wave AlGaAs (Aluminium Gallium Arsenide) diode laser was used for welding Indocyanine Green-loaded patches (ICG patches) to the dura. The ICG-loaded patches were fabricated using chitosan, a resistant, pliable and stable in the physiological environment biopolymer; moreover, their absorption peak was very close to the laser emission wavelength. Histology, thermal imaging and leak pressure tests were used to evaluate the bonding effect. We demonstrated that the application of 3 watts (W), pulsed mode (T 30 ms, T 3.5 ms) laser light induces optimal welding of the ICG patch to the dura mater, ensuring an average fluid leakage pressure of 216 ± 105 mmHg, falling within the range of physiological parameters. This study demonstrated that the thermal effect is limited and spatially confined and that the laser bonding procedure can be used to close the dura mater. Our results showed the effectiveness of this approach and encourage further experiments in in vivo models.