Abstract:

Objective Supercritical carbon dioxide fluid (SCF-CO₂) is a new green processing and high-efficiency finishing technology, nontoxic, nonflammable and can be recycled, which have been used to impregnate the drug into polymer matrix in biomedical field widely and is superior to the traditional finishing technology. In order to fabricate bioactive textile with good bioactive drug release property through SCF-CO₂impregnation processfor increasing the added value of clothing fabrics, it is necessary to analysis the variation and influence factors of release property of drug from bioactive textile fabricated by SCF-CO₂.

Method The bioactive drug nicotinamide with skin whitening, nourishing was used as the model drug, and viscose fabric was used as the substrate. Nicotinamide-loaded bioactive viscose fabrics processed by SCF-CO₂ under different temperatures (60, 70 and 80 ℃) and different pressures(12, 16 and 20 MPa), which were placed in the same release medium and measured the drug release amount in specific time by ultraviolet spectrophotometer. Ethanol was regarded as the release medium. Finally, the release curves that the drug release amount varied with time were drawn. The drug loading capacity was also measured. Besides, the release curves were fitted by different release models.

Results A higher absolute release quantity and a higher absolute release rate are obtained respectively when the supercritical CO₂(SCCO₂)temperature is 80 ℃, compared to 60, 70 ℃ of SCCO₂ temperature. Besides, the drug loading capacity increases with increasing SCCO₂temperature and the values are 6.165 4, 6.617 2 and 8.936 7 mg/g per weight of raw viscose fabric respectively. A higher absolute release quantity and a higher absolute release rate are also obtained respectively when the pressures are above 16 MPa as illustrated, compared to 12 MPa of SCCO₂ pressure. The drug loading capacity also increases with increasing pressure and the values are 0.838 7, 4.955 3 and 6.617 2 mg/g per weight of raw viscose fabric respectively. A lower cumulative release percentage and a lower cumulative release rate are obtained respectively when the SCCO₂ temperature is 60 ℃, which have an increasing tendency with increasing SCCO₂ temperature, and the cumulative release percentage can be as low as 87.6% when it reaches the releasing equilibrium. On the contrary, a lower cumulative release percentage and a lower cumulative release rate are obtained respectively when the SCCO₂ pressure is 20 MPa, which have a decreasing tendency with increasing SCCO₂ pressure, and the cumulative release percentage can be as low as 87.3% when it reaches the releasing equilibrium. The R² of Korsmeyer-Peppas model for all the release curves of nicotinamide-loaded viscose fabric processed by different SCCO₂ temperature, pressure is much higher than Zero-order release model, Higuchi model, and the R²is above 0.935 39 as depicted in Tab.1 and 2. Moreover, the corresponding diffusion index is generally below 0.45 except that the one processed under 60 ℃ of SCCO₂ temperature.

Conclusion The absolute release quantity and release rate of nicotinamide from viscose fabric are positively related to its loading capacity on the viscose fabric that vary with different SCCO₂ temperature and pressure. A higher loading capacity results in a higher absolute release quantity and a higher release rate. A lower cumulative release percentage and a lower cumulative release rate can be obtained when nicotinamide-loaded bioactive viscose fabric is processed by a lower SCCO₂ temperature or a higher SCCO₂ pressure. It means the cumulative release property is correlated to the density of SCCO₂. The release kinetics of nicotinamide-loaded viscose fabric processed by SCCO₂ are more consistent with Korsmeyer-Peppas model. Moreover, the diffusion behavior of nicotinamide from viscose fabric is mainly belong to Fick diffusion.

Key words: supercritical carbon dioxide fluid, nicotinamide, viscose fabric, absolute release quantity, absolute release rate, bioactive textile, elease behavior