Microparticulate polyelectrolyte complexes for gentamicin transport across intestinal epithelia

Figures & data

Table 1.  Formulation variables and dimensional properties of the microparticles.

Microparticles	Sample code	CaCl2 (%, w/v)	CS(%, w/v)	Mean size ± SD (μm)
Un-cross-linked	U	0	0	3.47 ± 1.36
Crosslinked	A	1.0	0	2.95 ± 0.88
	B	1.5	0	2.92 ± 1.09
	C	2.0	0	2.41 ± 0.59
Co-cross-linked	A1	1.0	0.5	2.30 ± 1.02
	A2	1.0	1.0	1.89 ± 0.79
	A3	1.0	2.0	2.31 ± 0.89
Fluorescent	A1F	1.0	0.5	2.16 ± 0.67

Table 2.  Calcium and GM content in microparticle samples.

Sample	Total calcium (%, w/w)	Associated calcium (%, w/w)	GM content (%, w/w)	GM encapsulation efficiency (%)
U	—	—	8.47 ± 0.69	93.18 ± 7.70
A	9.15 ± 0.12	9.00 ± 0.10	5.94 ± 0.62	65.34 ± 12.50
B	10.65 ± 0.71	9.88 ± 0.57	3.08 ± 0.21	33.88 ± 2.27
C	13.97 ± 0.57	12.69 ± 0.45	2.17 ± 0.51	23.87 ± 5.65
A1	8.03 ± 0.47	7.62 ± 0.50	5.55 ± 0.41	61.06 ± 4.58
A2	7.80 ± 0.27	7.41 ± 0.29	5.68 ± 1.17	62.49 ± 6.92
A3	5.80 ± 0.31	5.39 ± 0.34	5.60 ± 0.91	61.61 ± 10.55
A1F	8.21 ± 0.67	7.68 ± 0.49	5.42 ± 0.40	59.63 ± 4.45

Values represent the mean ± SD.

Figure 1.  SEM images of un-cross-linked (sample U) (a), cross-linked (sample A) (b), co-cross-linked (sample A1) (c), and co-cross-linked (sample A3) (d) microparticles.

Figure 2.  Size distribution of un-cross-linked (sample U), cross-linked (sample A), and co-cross-linked (sample A1) microparticles.

Figure 3.  EDX analysis coupled with SEM: relative sodium and calcium percentages calculated on element emission intensity from distinct microparticles. The image refers to the sample A1.

Figure 4.  Antimicrobial activity of un-cross-linked (sample U), cross-linked (sample A), and co-cross-linked (sample A1) microparticles.

Figure 5.  GM release from cross-linked microparticles in simulated gastrointestinal media.

Figure 6.  GM release from co-cross-linked microparticles compared with GM release from the sample A in simulated gastrointestinal media.

Figure 7.  Epifluorescence microscopy image of the sample A1F recovered from simulated gastrointestinal media.

Figure 8.  Image of a Peyer’s patch isolated from rat ileum.

Figure 9.  Interferential microscopy images of intestinal segments, including PP and perifollicular areas, from rabbit after perfusion treatment with microparticles: gut lumen surface (a), Bouin’s-fixed gut sections (spheroidal structures identified with microparticles are circled) (b). Original magnification ×40.

Figure 10.  Fluorescence microscopy images of intestinal segments from rat after perfusion treatment with microparticles: gut lumen surface (a), perfused segment in correspondence of a PP (b), perfused segment in correspondence of intestinal villi (c). Original magnification ×40.

Figure 11.  SEM image of the sample A1 after 30 min contact with pH 7.4 phosphate buffer solution.

Figure 12.  Cytofluorimetric analysis at 37°C (A) and 4°C (B): control (a), 3 h incubation (b), 6 h incubation (c).

Figure 13.  Confocal microscopy images of Caco-2 cells after nuclei staining: control under filter for green (a) and blue fluorescence (b); Caco-2 cells incubated at 37°C with the sample A1F under filter for green (c) and blue fluorescence (d).