aDepartment of Pharmaceutical Technology,Faculty of Pharmacy,Silpakorn University,Nakhon Pathom 73000, Thailand

bFaculty of Pharmacy,Siam University,Bangkok 10160,Thailand

Oxygen transmission of modifed natural rubber, poly(lactic acid)and chitosan porous structures for wound dressing

Sasiprapa Chitratthaa,b,*,Thawatchai Phaechamuda

aDepartment of Pharmaceutical Technology,Faculty of Pharmacy,Silpakorn University,Nakhon Pathom 73000, Thailand

bFaculty of Pharmacy,Siam University,Bangkok 10160,Thailand

A R T I C L E I N F O

Article history:

Available online 24 November 2015

Oxygen transmission

Natural rubber

Poly(lactic acid)

Chitosan

Porous

Oxygen is a signifcant factor essential to provide the additional energy source for the wound repairing process.Many polymeric materials have been employed recently in wound dressing such as natural rubber(NR)[1],poly(lactic acid)(PLA) and chitosan[2]because of their biocompatibility and biodegradability.In this study,the oxygen transmission rate(OTR) of modifed NR,PLA and chitosan porous structure was determined.The comparison for their OTR was investigated.

NR porous flms(NRTX)were fabricated by solvent casting method.NR solution was prepared by dissolving NR(STR 5L) in dichloromethane prior to addition of xanthan gum,which was previously dispersed in triethyl citrate and then mixed homogenously.The mixture was poured onto the petri dish and then placed in laminar hood to allow dichloromethane to evaporate overnight at room temperature.PLA porous flm(PPEG)was prepared using temperature change technique by solvent castingmethod.The10%w/wPLAwasdissolvedin dichloromethane.Polyethylene glycol 400(PEG)at 150%w/w of polymer was mixed with the PLA solution.The mixtures were poured onto the petri dish and suddenly placed at?20°C for 24 h and then allowed to dry at 60°C for 24 h.The 4%w/w chitosan solution(CL)was prepared by dissolving chitosan in 2%w/v lactic acid solution.Aluminum monostearate(Alst)(0, 0.5 and 2.5%w/w)was added into the previous mixture and then homogenized at 8000 Hz for 5 min using homogenizer.Subsequently,the mixtures were stirred for another 24 h using magnetic stirrer at 1000 rpm.Thereafter,the obtained mixtures were fabricated by using lyophilization technique by freezing at?20°C for 24 h prior to drying with freeze dryer. The lyophilized chitosan sponges were then treated by dehydrothermal treatment(DHT)at 110°C for 24 h in vacuum oven.The chitosan sponges containing 0,0.5 and 2.5%w/w Alst were named as CD,CD05 and CD25,respectively.OTR was performed using method modifed fromASTM1434-82.The samples were cut to ft and placed between the silicone rubber rings on two open 4 cm glass bottles volume 500 ml.Dry nitrogengas was swept through a chamber,where the test sample acted as the membrane separating this stream from an oxygen stream on the other side,and the gas rate was 100 ml/min.The test condition was 25°C,70±10%RH.The amount of oxygen was determined in the outgoing stream of the nitrogen side using gas chromatography(GC)until a constant amount of oxygen was achieved.The oxygen transmission rate(OTR)of flms was then calculated in the unit of g m?2day?1(n=3).

OTR of all test samples was shown in Fig.1.Plain NR,NRTX and plain PLA flms exhibited the low OTR,similarly.Since plain NR and PLA exhibited the dense and hydrophobic structure that oxygen gas could permeate diffculty.Even though NRTX was a porous inner-layer structure,it exhibited the thick densetop layer that was an oxygen barrier.PPEG showed the higher OTR than those flms because of its whole porous structure and hydrophilicity of PEG in the structure.CD0,CD05 and CD25 displayed the similar highest OTR.The hydrophobic Alst is contained in the CD05 and CD25 structure;however,the OTR was not different from that of CD0 owing to high porous topography,therefore the oxygen gas could freely permeate through this unique structure.The optimal conditions for oxygen for wound treatment have not been determined. However,the oxygen-impermeable dressings may be useful only in the early stages of healing,before granulation tissue formation,but the wound will be better healed by the oxygenpermeable dressings at 3 weeks[3].The OTR of porous NR,PLA and chitosan structures were compared.Chitosan sponge exhibited the higher OTR than PLA porous flm and NR porous flm,respectively(Fig.1).

Acknowledgments

The authors would like to thank Kotchamon Yodkhum, Pongsatorn Issarayungyuen,Dr.Wiwat Pichayakorn,Faculty of Pharmacy,Silpakorn University,Nakhon Pathom,Thailand and Faculty of Pharmacy,Siam University,Bangkok,Thailand for their kind support.This research work was kindly supported by The Thailand Research Fund(TRF)via The Royal Golden Jubilee Ph.D.Program(Grant No.PHD/0141/2552)and(Grant No. RDG5650126)from TRF.

R E F E R E N C E S

[1]Guidelli EJ,Kinoshita A,Ramos AP,et al.Silver nanoparticles delivery system based on natural rubber latex membranes.J Nanopart Res 2013;15:1536–1544.

[2]Mogos?anu GD,Grumezescu AM.Natural and synthetic polymers for wounds and burns dressing.Int J Pharm 2014;463:127–136.

[3]Pandit AS,Faldman DS.Effect of oxygen treatment and dressing oxygen permeability on wound healing.Wound Repair Regen 1994;2:130–137.

*E-mail address:sasi_toey@hotmail.com.

Peer review under responsibility of Shenyang Pharmaceutical University.

http://dx.doi.org/10.1016/j.ajps.2015.11.064

1818-0876/?2016 Production and hosting by Elsevier B.V.on behalf of Shenyang Pharmaceutical University.This is an open access article under the CC BY-NC-ND license(http://creativecommons.org/licenses/by-nc-nd/4.0/).