The use of differential scanning calorimetry to study the effects of gentamycin on fibrous collageneous membranes - Analytical Methods & Tools for Lyophilization

The use of differential scanning calorimetry to study the effects of gentamycin on fibrous collageneous membranes
Received 27 January 2004; revised 4 June 2004; accepted 29 June 2004. Available online 19 August 2004.
E. Siapia, T. Mavromoustakosa, , , V. Trandafirb, B. Albuc and P. Budrugeacd
Thermochimica Acta
Volume 425, Issues 1-2 , 20 January 2005
ScienceDirect
aNational Hellenic Research Foundation, Institute of Organic and Pharmaceutical Chemistry, Vas. Constantinou 48, 11635 Athens, Greece
bNational Research and Development Institute for Textile and Leather Ò Division Leather and Footwear Research Institute, 93 Ion Minulescu, Bucharest, Romania
cResearch Center for Macromolecular Materials and Membranes, Splaiul Independentei 202B, Bucharest, Romania
dICPE Ò CA, Advanced Research Institute for Electrical Engineering, Splaiul Independentei 313, Bucharest, Romania
Abstract
The protein collagen is the most predominant and important protein of the skin and therefore its physicochemical and thermal properties are important to be known. DSC has been applied in order to study the thermal changes caused by using different concentrations of the gentamycin antibiotic in fibrous membranes FM, named AMATCOL at different scanning rates. The thermal effect consisting of several peaks of the fibrous collageneous membrane alone or with different percentages of drug is simplified to a broad peak after 24 h equilibration time. The 35Ò70 ?C endothermic effect attributed to the collapse of the tripple-helical domain of collagen due to the dehydration is affected by the presence of gentamycin. The endothermic peaks due to vaporization of bound water at the temperatures of 90Ò120 ?C are also affected by the presence of gentamycin. This region consists of two peaks at low percentage of gentamycin and at higher percentages the peak near 120 ?C decreases in intensity and finally disappears. The re-absorption of the water is more significant in the preparations containing gentamycin after 24 h equilibration time indicating that antibiotic makes a more stable complex with collagen molecules aiding this process. A minimum of re-absorption occurs when the concentration of gentamycin is 2% w/w in accordance with pore size and nitrogen gas permeability measurements. The collagen denaturation occurs at higher temperature when gentamycin is incorporated in fibrous membranes FM. This is an evidence that gentamycin stabilizes the cross-linkings between structural units (covalent, hydrophobic links) due to its interactions with collagen and water. Data resulted from differential scanning calorimetry (DSC) have been corroborated with those resulted from the porosity analysis. Specific morphology of fibrous collageneous membranes FM structure, containing macro-, micro-, and nano-pores resulted from freeze drying, acts on the gas and water vapor permeability, as well as water absorption. These characteristics are important in trans-dermal carriage of gentamycin contained in FM membranes.
Keywords: Collagen type 1; Fibrous membranes; Gentamycin; Thermo-oxidation
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