The influence of operating parameters on the drug release and antibacterial performances of alginate fibrous dressings prepared by wet spinning

Figures & data

Figure 1. (A) Representative of a fresh alginate hydrogel sample made by wet spinning, (B–F) are pictures (left) and SEM micrographs (right) of dry samples: (B) control (air pressure = 6 bar, needle diameter = 150 μm, calcium concentration = 0.5 w/v%, alginate concentration = 1.5 w/v%), (C) sample P (air pressure = 6 bar), (D) sample D (needle diameter = 200 μm), (E) sample Ca (calcium concentration = 5 w/v%), (F) sample A (alginate concentration = 3 w/v%).

Figure 2. The fiber sizes of the dry samples. Data are presented as the mean ± SD (n = 15). *Indicates data significantly different from the control sample (p < 0.05).

Figure 3. Young’s modulus of the rehydrated samples. Data are presented as the mean ± SD (n = 6). *Indicates data significantly different from the control sample (p < 0.05).

Figure 4. The swelling ratios of the dry samples over 90 min. Data are presented as the mean ± SD (n = 6). *Indicates data significantly different from the control sample at 90 min (p < 0.05).

Figure 5. The water vapor transmission rate (WVTR) for the open cup and dry samples. Data are presented as the mean ± SD (n = 6). *Indicates data being significantly different from the control sample (p < 0.05).

Figure 6. The cumulative TCH release of different samples over 6 h in PBS. Data are presented as the mean ± SD (n = 6). The total amount of TCH released within 48 h was the amount of TCH loaded on the sample. The percentages of TCH released after 6 h is shown on the figure. The cumulative amounts of TCH released from sample A at 6 h and 48 h were higher than those of the control, while those of samples P, D and Ca were lower (p < 0.05).

Figure 7. (A) Representative pictures of the antibacterial effect of samples releasing tetracycline HCl (TCH). (B) The bacterial inhibition zone of the samples loaded with (TCH). Data are presented as the mean ± SD (n = 8). *Indicates data significantly different from the control sample (p < 0.05).

Table 1. The different operating parameters of the wet-spinning system and a qualitative assessment of the appearances of the final products

Sample denotation^a	Parameters of the wet-spinning system				Qualitative observation of appearances compared with The control^b
	Air pressure (bar)	Needle size (μm)	Calcium conc. (w/v%)	Alginate conc. (w/v%)	Fiber size		Fibrous structure
					Larger	Smaller	Compact	Loose
Control	6	150	5.0	1.5
P	3	150	5.0	1.5	++			++
D	6	200	5.0	1.5	+			+
Ca	6	150	0.5	1.5	+		+
A	6	150	5.0	3	similar			+

+, observed; ++, observed in a more significant way than others; ^aAlginate samples are coded according to the variable in the manufacturing process. For example, P is a sample manufactured with an air pressure that was different from the control. ^bThe observations were based on the pictures in Figure 1.