Name: Fabrication and Application of Rose Bengal-chitosan Films in Laser Tissue Repair (Video) | JoVE Journal
Uploaded: 2012-10-23T15:00:00.000+00:00
Duration: 10 min 6 s
Description: Learn to fabricate laser-activated chitosan adhesive films using rose Bengal powder for peripheral nerve repair. This biocompatible method minimizes tissue damage compared to traditional sutures.

ai_agent_IP

ai_agent

maintenance

instantTrialDurationMinutes

isBiopharma

enableNewMyJoveSectionDesign

educationFeatures

seoMetaApi

ai_copilot_institution_blacklist

ai_chat_institution_blacklist

freeAccessWindow

ssoRoleCapture

scheduledMaintenanceBanner

joveLabsFeatures

disable_autoplay_for_bots

extended_trial_duration

5 minutes

This work was supported by the UWS Research Grant.

1. Chitosan Adhesive Preparation
<ol>
 <li>The chitosan powder is soluble in acetic acid solution; for the preparation of a stock solution of acetic acid (2% v/v), add 10 ml glacial acetic acid to 490 ml deionized water (DI-H2O).</li>
 <li>For the preparation of a stock solution of Rose Bengal (RB) (0.01% w/v) in acetic acid, weigh 5 mg of RB in a vial wrapped with aluminum foil to avoid photobleaching. Add 0.5 ml of DI-H2O to dissolve the powder then add 49.5 ml of the acetic acid stock solution (described in section 1.1).</li>
 <li>For the preparation of chitosan solution (1.7% w/v), weigh 0.85 g of chitosan powder (medium MW, 85% degree of acetylation) and add to 50 ml of RB acetic acid solution. The control was prepared by dissolving the chitosan in acetic acid solution without RB.</li>
 <li>Add a magnetic stirrer to the chitosan mixture and stir at room temperature. To ensure complete dissolution of the components, stir the chitosan in acetic acid + RB for two weeks and the chitosan in acetic acid for 5 days (control). When chitosan is dissolved, the solution pH increases from ~2.6 to ~3.9. Note that RB is poorly soluble in acidic pH and it requires an increase in the pH of the solution and an extended stirring time to dissolve.</li>
 <li>Centrifuge the solutions at 3270 x g for 1 hr and collect the supernatant using, for example, a sterile 10 ml syringe. Make sure not to disturb the impurity pellet. During this step, the solution is cleaned from macroscopic impurities and insoluble matter.</li>
 <li>Inject the (centrifuged) chitosan solution on a flat perpex slab using a sterile syringe. The thickness of the dried film depends on the ratio between the dispensed amount of solution and the surface area over which the solution is spread. Ensure that the solution is free from air bubbles and evenly spread on the slab. To obtain thin films with ~13 μm thickness, inject ~1 ml solution over 12 cm2 surface area (dimensions~3x4 cm, Figure 1A).</li>
 <li>Cover the Perspex slab with a screen, made of aluminum foil for example, to avoid photobleaching of the solution. Ensure that enough air ventilation is guaranteed to dry the solution under the screen.</li>
 <li>Leave the solution to dry at room temperature (25 °C) and pressure (1 atm) till the resulting film is insoluble in water and does not swell macroscopically. This is typically achieved in 2 weeks.</li>
 <li>Detach the films carefully using a thin and flat spatula: these films can be easily peeled off the Perspex slab without damaging them.</li>
 <li>Measure the thickness of the films using a micrometer.</li>
 <li>Cut the adhesive in rectangular strips with a clean sharp scissor and place them between sterile glass slides to preserve their flat shape. Wrap the slides in aluminum foil for light shielding and store them at room temperature. Label the adhesives with or without RB as "rose adhesive" or "chitosan adhesive" respectively.</li>
 <li>The rose adhesive films can be sterilized using ethanol (90%) or with gamma radiation (0.1 KGy/h for 24 hr)4,5.</li>
</ol>
2. Adhesive Optical Attenuation
<ol>
 <li>Fix the rose adhesive inside a quartz cuvette.</li>
 <li>Record its attenuated spectrum in the range of 400 - 800 nm using a dual-beam spectrophotometer4.</li>
 <li>Assuming the validity of Beer's law, calculate the attenuation length of the adhesive as follows: I = I0e-Ax where I0 is the incident beam intensity, 1/A is the attenuation length, and x is the film thickness.</li>
 <li>Repeat steps 2.1 to 2.3 for the chitosan adhesive to serve as a control.</li>
</ol>
3. In Vitro Application: Laser Tissue Bonding on Intestine
<ol>
 <li>Harvest calf intestine immediately after animal euthanasia and store at -80 °C.</li>
 <li>Prior to use, defrost and hydrate the tissue by immersing it in DI-H2O for 10 min.</li>
 <li>Bisect the tissue into sections (2 x 1 cm) using a #10 blade under an operating microscope (x10). Keep the sections moist using DI-H2O.</li>
 <li>Bring the incision stumps close together (end to end). Wipe excess water off the surface using cotton tips.</li>
 <li>Place a rose adhesive strip (10 x 6 mm) across the incision on the serosa layer with microforceps ensuring full contact with the intestine (Figure 2).</li>
 <li>The tissue adhesion of the rose adhesive is activated by a diode-pumped solid state laser, which is coupled to a multimode optical fiber (core diameter 200 μm)4.</li>
 <li>Set the power level of the laser to 180 mW and irradiate the adhesive for ~6 min with a beam spot size of ~5 mm, using the parameters listed in Table 1. Spot-irradiate the adhesive ensuring that each spot is irradiated for ~5 seconds before moving the beam to the adjacent spot. This procedure guarantees that the laser beam scans the whole surface area of the adhesive several times.</li>
 <li>To assess the tissue bonding strength, clamp a sample to a calibrated single column tensiometer (Instron, MA, USA) using mechanical grips. Move the grips at 22 mm/min until the two tissue stumps separate4.</li>
 <li>Place a rose adhesive on the tissue as described in step 3.5. Do not irradiate the sample and measure the tissue bonding strength as described in step 3.8. This sample serves as a control.</li>
</ol>
4. In Vivo Application: Tibial Nerve Anastomosis
<ol>
 <li>Sedate the Wistar rat with isoflurane/O2 mixture (4% during induction, 2% thereafter)5. Subcutaneously inject Buprenex (0.03 mg/kg) to provide intra-operative analgesic activity and alleviate possible pain or discomfort.</li>
 <li>The following surgical procedure should be performed under an operating microscope (x10). Make an oblique skin incision about 3 cm long in the dorso-lateral part of the right thigh and expose the tibial nerve with a muscle-splitting approach through the gluteal muscles2.</li>
 <li>Partially dissect and trim the adventitia of the tibial nerve using straight micro-scissors and absorb excess water with sterile gauze or cotton tips.</li>
 <li>Cut the tibial nerve with micro-scissors.</li>
 <li>Position a sterile chitosan strip (dimensions 5 x 4 mm) underneath the tibial nerve using micro-forceps.</li>
 <li>Approximate the nerve stumps end-to-end with micro-forceps over the rose adhesive strip.</li>
 <li>The strip fully adheres to the nerve forming a collar, which can assist with the rotation of the nerve during the laser irradiation of the strip.</li>
 <li>Activate the rose adhesive with the laser as described in steps 3.6) and 3.7).</li>
 <li>Trim the redundant rose adhesive from the collar of the operated nerve.</li>
 <li>Close the muscles and skin with five 3-0 sutures5.</li>
 <li>Standard post-operative recovery procedures should be followed including daily inspection for dehiscence or pus formation and analgesic administration, if required.</li>
</ol>
5. Representative Results
The films that are obtained are bright rose in color, thin and have a smooth surface (Figure 1). They are also flexible and can be rolled into tubes of small diameter without causing tears or any other apparent damage (Figure 1B). The rose adhesive has two absorption peaks at 530 and 562 nm; the green laser is thus strongly absorbed by the adhesive and the corresponding attenuation length at 532 nm is ~12 μm (Figure 3). In contrast, chitosan films without RB attenuates weakly the laser (1/A ~162 μm), likely due to scattering. It appears from the spectra plot that no significant aggregation of RB occurs in the films.
The rose adhesive bonds firmly to the intestine upon laser irradiation (Figure 2) achieving a typical maximum load at failure of 0.9 ± 0.4 N (n=30). The adhesive strength was estimated as the maximum load divided by the adhesive surface area, namely, 15 ± 6 kPa (n=30). The non-irradiated rose adhesive bonded significantly less to tissue (2 ± 2 kPa, n=30, unpaired t-test p&lt;106). The in-vivo anastomosis of the tibial nerve was successfully achieved following the application and bonding of the rose adhesive in conjunction with the green laser. One week postoperatively, the operated nerve was in continuity and the repair strength was 17 ± 9 kPa (n=10).
<img alt="Adhesive application with rose adhesive solution, experimental setup showing adhesion process." src="/files/ftp_upload/4158/4158fig1.jpg" data-altupdatedat="1787630408000" data-alt="Figure 1"> 
Figure 1. A) The RB-chitosan solution is casted on a flat Perspex slab (slab thickness~5 mm). Graph paper is placed underneath the slab to facilitate the dry-cast step. The water-insoluble film is obtained two weeks after casting. B) The rose adhesive is flexible and can be rolled into a small cylinder.
<img alt="Tissue section with rose adhesive; labeled bisection line; experimental setup for tissue adhesion study." src="/files/ftp_upload/4158/4158fig2.jpg" data-altupdatedat="1787630408000" data-alt="Figure 2"> 
Figure 2. The rose adhesive is bonded to calf intestine after laser irradiation. Uniform irradiation is applied on the RB adhesive during tissue-bonding; however selected spots are shown in this picture to illustrate the photo-bleaching effect of the laser on the adhesive.
<img alt="Absorption spectrum chart of adhesives; wavelength vs. absorption peaks at 562 nm and 530 nm." src="/files/ftp_upload/4158/4158fig3.jpg" data-altupdatedat="1787630408000" data-alt="Figure 3"> 
Figure 3. The absorption spectrum (in arbitrary units) of the rose adhesive shows two peaks at 530 and 562 nm. The green laser (λ= 532 nm) is thus strongly absorbed by the adhesive during the laser exposure. The chitosan adhesive without RB absorbs poorly the laser beam.
<table border="1">
 <tbody>
 <tr>
 <td> </td>
 <td>n</td>
 <td>Area (mm2)</td>
 <td>Power (W)</td>
 <td>Time (s)</td>
 <td>Fluence (J/cm2)</td>
 <td>I (W/cm2)</td>
 <td>Max Load/Area (kPa)</td>
 </tr>
 <tr>
 <td>Adhesive+Laser</td>
 <td>30</td>
 <td>60 ± 10</td>
 <td>0.18 ± 0.03</td>
 <td>365 ± 5</td>
 <td>~110</td>
 <td>~0.9</td>
 <td>15 ± 1</td>
 </tr>
 <tr>
 <td>Adhesive</td>
 <td>30</td>
 <td>60 ± 10</td>
 <td>NA</td>
 <td>NA</td>
 <td>NA</td>
 <td>NA</td>
 <td>2 ± 2</td>
 </tr>
 </tbody>
</table>
Table 1. Legend. n, sample number; Area, surface area of the rose adhesive (mean ± maximum error); Power, laser power (mean ± maximum error); Time, irradiation time (mean ± maximum error); Fluence, average laser fluence; I, estimated irradiance; Max Load/Area, maximum load at failure of the repaired tissue divided by the adhesive surface area, (mean ± SE).

<ol><li>O'Neill, A. C., Winograd, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Microvascular+anastomosis+using+a+photochemical+tissue+bonding+technique%5BTitle%5D)+AND+%22Lasers+Surg.+Med%22%5BJournal%5D)">Microvascular anastomosis using a photochemical tissue bonding technique.</a> Lasers Surg. Med. 39, 716-722 (2007).</li>
<li>Yao, M., Yaroslavsky, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Phototoxicity+is+not+associated+with+photochemical+tissue+bonding+of+skin%5BTitle%5D)+AND+%22Lasers+Surg.+Med%22%5BJournal%5D)">Phototoxicity is not associated with photochemical tissue bonding of skin.</a> Lasers Surg. Med. 42, 123-131 (2010).</li>
<li>Lauto, A., Mawad, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Photochemical+Tissue+Bonding+with+Chitosan+Adhesive+Films%5BTitle%5D)+AND+%22Biomedical+Engineering+OnLine%22%5BJournal%5D)">Photochemical Tissue Bonding with Chitosan Adhesive Films.</a> Biomedical Engineering OnLine. 9, 47(2010).</li>
<li>Chan, B. P., Kochevar, I. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Enhancement+of+porcine+skin+graft+adherence+using+a+light-activated+process%5BTitle%5D)+AND+%22J.+Surg.+Res%22%5BJournal%5D)">Enhancement of porcine skin graft adherence using a light-activated process.</a> J. Surg. Res. 108, 77-84 (2002).</li>
<li>Lauto, A., Faster, L. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Sutureless+nerve+repair+with+laser-activated+chitosan+adhesive%3A+a+pilot+in+vivo+study%5BTitle%5D)+AND+%22Photomed.+Laser+Surg%22%5BJournal%5D)">Sutureless nerve repair with laser-activated chitosan adhesive: a pilot in vivo study.</a> Photomed. Laser Surg. 26, 227-234 (2008).</li>
<li>Lauto, A., Hook, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Chitosan+adhesive+for+laser+tissue+repair%3A+in+vitro+characterization%5BTitle%5D)+AND+%22Lasers+Surg.+Med%22%5BJournal%5D)">Chitosan adhesive for laser tissue repair: in vitro characterization.</a> Lasers Surg. Med. 36, 193-201 (2005).</li>
<li>Au, V., Madison, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Effects+of+singlet+oxygen+on+the+extracellular+matrix+protein+collagen%3A+oxidation+of+the+collagen+crosslink+histidinohydroxylysinonorleucine+and+histidine%5BTitle%5D)+AND+%22Arch.+Biochem.+Biophys%22%5BJournal%5D)">Effects of singlet oxygen on the extracellular matrix protein collagen: oxidation of the collagen crosslink histidinohydroxylysinonorleucine and histidine.</a> Arch. Biochem. Biophys. 384, 133-142 (2000).</li>
<li>Encinas, M. V., Rufs, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Xanthene+dyes%2Famine+as+photoinitiators+of+radical+polymerization%3A+A+comparative+and+photochemical+study+in+aqueous+medium%5BTitle%5D)+AND+%22Polymer%22%5BJournal%5D)">Xanthene dyes/amine as photoinitiators of radical polymerization: A comparative and photochemical study in aqueous medium.</a> Polymer. 13, 2762-2767 (2009).</li>
<li>Pini, R., Rossi, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+new+technique+for+the+closure+of+the+lens+capsule+by+laser+welding%5BTitle%5D)+AND+%22Ophtalmic+Surgery+Lasers+%26+Imaging%22%5BJournal%5D)">A new technique for the closure of the lens capsule by laser welding.</a> Ophtalmic Surgery Lasers & Imaging. 39, 260-2626 (2008).</li>
<li>Wieken, K., Angioi-Duprez, K., Lim, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Nerve+anastomosis+with+glue%3A+comparative+histologic+study+of+fibrin+and+cyanoacrylate+glue%5BTitle%5D)+AND+%22J.+Reconstr.+Microsurg%22%5BJournal%5D)">Nerve anastomosis with glue: comparative histologic study of fibrin and cyanoacrylate glue.</a> J. Reconstr. Microsurg. 19, 17-20 (2003).</li>
<li>Menovsky, T., Beek, J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Laser%2C+fibrin+glue%2C+or+suture+repair+of+peripheral+nerves%3A+a+comparative+functional%2C+histological%2C+and+morphometric+study+in+the+rat+sciatic+nerve%5BTitle%5D)+AND+%22J.+Neurosurg%22%5BJournal%5D)">Laser, fibrin glue, or suture repair of peripheral nerves: a comparative functional, histological, and morphometric study in the rat sciatic nerve.</a> J. Neurosurg. 95, 694-699 (2001).</li>
<li>García, P., Jorge, H. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Comparative+study+of+the+mechanical+behavior+of+a+cyanoacrylate+and+a+bioadhesive%5BTitle%5D)+AND+%22J.+Mater.+Sci.+Mater.+Med%22%5BJournal%5D)">Comparative study of the mechanical behavior of a cyanoacrylate and a bioadhesive.</a> J. Mater. Sci. Mater. Med. 15, 109-115 (2004).</li>
<li>Lauto, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Integration+of+extracellular+matrix+with+chitosan+adhesive+film+for+sutureless+tissue+fixation%5BTitle%5D)+AND+%22Lasers+Surg.+Med%22%5BJournal%5D)">Integration of extracellular matrix with chitosan adhesive film for sutureless tissue fixation.</a> Lasers Surg. Med. 41, 366-371 (2009).</li>
</ol>

No conflicts of interest declared.

The rose adhesive fabrication is based on a simple dry-cast process, though the dissolution of RB in acidic pH requires prolonged stirring of the chitosan solution. It is important to let the solution dry up until it becomes a water-insoluble film. This happens when the weight water content is ~10% in the dried film6. Insoluble films are usually obtained 2 weeks after dry-casting at standard conditions of temperature and pressure (~25 &deg;C and ~1 atm). The mechanism of tissue bonding is not clear yet, althou...

<table><tbody><tr><td>Rose Bengal</td><td>Sigma-Aldrich</td><td>632-69-9</td><td> </td></tr><tr><td>Chitosan (medium MW)</td><td>Sigma-Aldrich</td><td>10318AJ</td><td> </td></tr><tr><td>Glacial acetic acid</td><td>Sigma-Aldrich</td><td>08050051</td><td>2% v/v in DI water</td></tr><tr><td>Magnetic stirrer</td><td>Heidolph</td><td>MR Hei-Mix S</td><td> </td></tr><tr><td>Centrifuge</td><td>Beckman Coulter Inc.</td><td>Allegra X-12R</td><td> </td></tr><tr><td>Spectrophotometer</td><td>Varian Inc., Agilent</td><td>Cary 4000 UV-Visible</td><td> </td></tr><tr><td>Laser</td><td>CNI Laser</td><td>MGL-532</td><td> </td></tr><tr><td>Micrometer</td><td>Mitutoyo</td><td>Series 227</td><td> </td></tr><tr><td>Surgical microscope</td><td>Carl Zeiss, Inc.</td><td>OPMI</td><td> </td></tr></tbody></table>

fabrication and application of rose bengal-chitosan films in laser tissue repair

Fabrication and Application of Rose Bengal-chitosan Films in Laser Tissue Repair

Photochemical tissue bonding (PTB) is a sutureless technique for tissue repair, which is achieved by applying a solution of rose bengal (RB) between two tissue edges1,2. These are then irradiated by a laser that is selectively absorbed by the RB. The resulting photochemical reactions supposedly crosslink the collagen fibers in the tissue with minimal heat production3. In this report, RB has been incorporated in thin chitosan films to fabricate a novel tissue adhesive that is laser-activated. Adhesive films, based on chitosan and containing ~0.1 wt% RB, are fabricated and bonded to calf intestine and rat tibial nerves by a solid state laser (&lambda;=532 nm, Fluence~110 J/cm2, spot size~0.5 cm). A single-column tensiometer, interfaced with a personal computer, is used to test the bonding strength. The RB-chitosan adhesive bonds firmly to the intestine with a strength of 15 &plusmn; 6 kPa, (n=30). The adhesion strength drops to 2 &plusmn; 2 kPa (n=30) when the laser is not applied to the adhesive. The anastomosis of tibial nerves can be also completed without the use of sutures. A novel chitosan adhesive has been fabricated that bonds photochemically to tissue and does not require sutures.

Sutures are usually needed to repair tissue during surgical procedures. However, their application can be problematic as they are invasive and may damage tissue. The fabrication and application methods of a novel tissue adhesive are here reported. This adhesive film is laser-activated and does not require the use of sutures.

Photochemical tissue bonding (PTB) is a sutureless technique for tissue repair, which is achieved by applying a solution of rose bengal (RB) between two ...

The overall goal of this procedure is to fabricate a laser activated chitosan adhesive and illustrate how to apply it when repairing peripheral nerves. This is accomplished by first Solubilizing chitosan and rose Bengal powder in acetic acid solution. The second step of the procedure is to dry cast the solution to obtain a thin film.The third step is to expose the rat nerve and dissect it. The final step is to place the film around the dissected nerve and irradiate it with a green laser to bond the film to the tissue. Ultimately, the strength with which rose film bonds to the tissue is measured using a calibrated tensiometer.The laser adhesive is biocompatible and has the advantage of bonding directly to the tissue. This makes it very useful for repairing tissue that is deep and difficult to get to where sutures would be difficult. It would also have the advantage of repairing tissue where watertight closure is important, such as the dura or the bowel.It is important to demonstrate visually the alto and adhesive technique because several steps are involved in the adhesive preparation and also because the surgical procedure requires particular care when the adhesive is applied on tissue. Most of the demonstration will be done by Matt Barton, who is a postgraduate student in my laboratory, and the surgical operation will be done by Professor Marcus Studley from Quare University. Begin by preparing a Kita sand solution in rose Bengal laced acetic acid.A control solution can simply lack the rose Bengal set up the solution with a magnetic stir at room temperature. It will be ready in about two weeks or five days for controls without rose Bengal. During this time, the pH increases from roughly 2.6 to 3.9 as the chitosan dissolves.Once prepared, centrifuge the solution for an hour and separate the solution from the impurity pellet. By gentle aspiration, do not disturb the pellet. Using a sterile syringe, inject the solution on a flat perspec slab.Spread the solution evenly without making any air bubbles For a film with a thickness of roughly 13 microns, spread a milliliter of solution over 12 square centimeters. Cover the Perspex slab with an aluminum foil screen to avoid photo bleaching of the solution, but leave enough ventilation space for the film to dry out. Leave the solution to dry at room temperature and pressure.Once the film has dried. Use a thin spatula to carefully pry it from the slab to test. If the adhesive is dry, cut a small sample and place it in a vial containing water.When the film is insoluble and does not swell macroscopically, it is dry. This typically takes two weeks. Then measure the thickness of the film using a micrometer with clean, sharp scissors.Cut the film into rectangular strips of the size required for your application. Store the pieces of rose adhesive or control adhesive between sterile glass slides wrapped in aluminum foil and at room temperature. Before using the film in an application, determine its optical attenuation.This is accomplished by fixing a small piece of film in a quartz vete. Then in a dual beam spectrophotometer record the attenuated spectrum of the film between 400 and 800 nanometers. The measurements can be interpreted using beer's law to provide the attenuation length, which will be comparable to the thickness of the film.For this protocol, calf intestine must have been harvested immediately after animal euthanasia and stored at minus 80 degrees Celsius. Defrost and hydrate the tissue by immersing it in deionized water for 10 minutes. Then bisect the tissue into two centimeter by one centimeter sections using a number 10 blade under an operating microscope at low power.Keep the sections moist with drops of water to bond two sections. Place them end to end and wipe any excess water off the surface. Using cotton tips with micro forceps.Place a strip of rose adhesive film across the incision on the ciero layer. Make certain the film is in full contact with the intestine. Prepare the DDE pumped solid state laser coupled to a multi-mode optical fiber.Check that the laser parameters are set correctly. Now irradiate the adhesive. The beam spot size should be about five millimeters wide where it contacts the rows adhesive spot irradiate each portion of the adhesive for about five seconds.Ultimately, the surface is scanned several times over about six minutes. Remove the irradiated sample. To assess the tissue bonding strength.Clamp a sample to a calibrated single column tensiometer. Using mechanical grips. Move the grips at 22 millimeters per minute until the two two tissue stumps separate as a control.Place a rose adhesive on the tissue. Do not irradiate the sample and measure the tissue's bonding strength. For this procedure, the rose adhesive films must be sterilized.This can be done using 90%ethanol or with gamma radiation. Sedate a wistar rat with 4%gaseous isof fluorine and reduce the concentration to 2%when the animal is no longer responsive to a pain reflex. Test like a tow pinch, shave and sanitize the rat's thigh.Position it for surgery under an operating microscope, make an oblique skin incision of about three centimeters in the dorsolateral part of the right thigh. Expose the tibial nerve with the muscle splitting approach through the gluteal muscles using straight micro scissors. Partially dissect and trim the adventitia of the tibial nerve.Absorb any excess fluids with sterile gauze or cotton tips. Now cut the tibial nerve using micro forceps. Position a sterile rose adhesive strip underneath the tibial nerve.Then approximate the nerve stumps end to end over the rose adhesive strip. It is important that the nerves be tension free. The strip will fully adhere to the nerve forming a collar which can assist with the rotation of the nerve.During laser irradiation, proceed to activate the rose adhesive with the laser as previously described. Finally, close the muscles and skin with five three aught sutures and follow standard postoperative protocols for the rat's recovery. Following the outlined protocol.The films obtained are bright rows in color, thin, and have a smooth surface. The films are also flexible and can be rolled into tubes of small diameter without causing tears or any other apparent damage. The rose adhesive has two absorption peaks at 530 and 562 nanometers.The green laser is thus strongly absorbed by the adhesive and the corresponding attenuation length at 532 nanometers is roughly 12 microns. In contrast, Esan films without RB attenuate weekly with the laser. The rose adhesive bonds firmly to the intestine upon laser irradiation achieving a typical maximum load at failure of about one Newton.The adhesive strength was estimated as the maximum load divided by the adhesive surface area. The non irradiated rose adhesive bonded significantly less to tissue. It is important to dry the keto and adhesive until it's completely insoluble in water.It takes about two weeks. Also, whenever you make the adhesive, you need acids and acids should be handled in a fume hood. Remember also that lasers are involved in this procedure and they can be very dangerous, so you need to wear laser goggles all the time.

fabrication-application-rose-bengal-chitosan-films-laser-tissue

Research

JoVE Journal

Bioengineering

The fabrication of a novel, flexible thin film surgical adhesive from FDA approved ingredients, chitosan and indocyanine green is described. Bonding of this adhesive to collagenous tissue through a simple activation process with a low-powered infra-red laser is demonstrated.

A Chitosan Based, Laser Activated Thin Film Surgical Adhesive, 'SurgiLux': Preparation and Demonstration

A major hurdle in current stem cell therapies is determining the most effective method to deliver these cells to host tissues. Here, we describe a chitosan-based delivery method that is efficient and simple in approach, while allowing adipose-derived stem cells to maintain their multipotency.

Constructing a Collagen Hydrogel for the Delivery of Stem Cell-loaded Chitosan Microspheres

This article describes a biofabrication approach:  deposition of stimuli-responsive polysaccharides in the presence of biased electrodes to create biocompatible films which can be functionalized with cells or proteins. We demonstrate a bench-top strategy for the generation of the films as well as their basic uses for creating interactive biofunctionalized surfaces for lab-on-a-chip applications.

Bridging the Bio-Electronic Interface with Biofabrication

This protocol aims to alleviate the limitation of poor cell engraftment for stem cell treatment of myocardial infarctions through the use of a hydrogel system and a fibrin-based glue. With this approach, cell-to-tissue contact post-infarction can be maintained, increasing the therapeutic potential of beneficial agents at the site of injury.

A Hydrogel Construct and Fibrin-based Glue Approach to Deliver Therapeutics in a Murine Myocardial Infarction Model.

An injectable tissue engineering scaffold composed of poly(N-isopropylacrylamide)-graft-chondroitin sulfate (PNIPAAm-g-CS)-containing alginate microparticles was prepared. The adhesive strength, swelling properties and in vitro biocompatibility are analyzed in this study. The characterization techniques developed here may be applicable to other thermogelling systems.

Synthesis of Thermogelling Poly(N-isopropylacrylamide)-graft-chondroitin Sulfate Composites with Alginate Microparticles for Tissue Engineering

Free solution capillary electrophoresis is a fast, cheap and robust analytical method that enables the quantitative monitoring of chemical reactions in real time. Its utility for rapid, convenient and precise analysis is demonstrated here through analysis of covalent peptide grafting onto chitosan films for improved cell adhesion.

Capillary Electrophoresis to Monitor Peptide Grafting onto Chitosan Films in Real Time

Here, we present protocols of culturing human periodontal ligament (PDL) cell spheroids by chitosan films. The culture of three-dimensional (3D) cellular spheroids provides an alternative to conventional tissue culture polystyrene (TCPS) culture system.

Formation of Human Periodontal Ligament Cell Spheroids on Chitosan Films

The present protocol describes a non-emulsion-based method for the fabrication of chitosan-genipin microgels. The size of these microgels can be precisely controlled, and they can display pH-dependent swelling, degrade in vivo, and be loaded with therapeutic molecules that release over time in a sustained manner, making them highly relevant for tissue engineering applications.

Fabrication of Size-Controlled and Emulsion-Free Chitosan-Genipin Microgels for Tissue Engineering Applications

Mechanically isolated stromal vascular fraction (SVF) in combination with a fibrin hydrogel offers an easy and efficient carrier for viable adipose-derived stromal cells for various indications, including tissue engineering and or wound healing purposes. Here, we present the preparation of a mechanical SVF (mSVF)-fibrin hydrogel construct for translational research and clinical application.

The Combination of Mechanically Isolated Stromal Vascular Fraction and Fibrin Hydrogel: A Processing Protocol

This study presents a benchtop model designed to evaluate the compatibility of wound dressing materials with negative pressure wound therapy systems by assessing pressure and fluid collection over 72 h under continuous and intermittent pressure settings.

Development of a Benchtop Model for Evaluating the Compatibility of Wound Dressing Materials with Negative Pressure Wound Therapy Systems

A reproducible protocol is presented for the preparation, enrichment, and application of an in situ blue‑light–crosslinkable gelatin–riboflavin hydrogel for corneal stromal wound repair in rabbits, including procedural steps for surgical handling, partial tarsorrhaphy, and postoperative care.

Fabrication and Surgical Application of Enriched Photo-crosslinked Gelatin&#8211;Riboflavin Hydrogels for Corneal Wound Repair in Rabbits

Learn to fabricate laser-activated chitosan adhesive films using rose Bengal powder for peripheral nerve repair. This biocompatible method minimizes tissue damage compared to traditional sutures.

Fabrication and Application of Rose Bengal-chitosan Films in Laser Tissue Repair

Explore More Videos