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. 2023 Feb 4;15(2):522. doi: 10.3390/pharmaceutics15020522

Figure 1.

Figure 1

A graph presenting the categorization of articles constituting the core of this review, in which the physicochemical properties of extracellular vesicles (EVs) of probiotics were described. Among the 60 of them, 15 and 45 concerned Gram-negative and Gram-positive bacteria, respectively. All articles assessed the size of the produced EVs, of which 49 determined it using only one technique (21 with electron microscopy [51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71], 19 with NTA [72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90], and 9 with DLS [42,45,49,50,91,92,93,94,95]), while 11 used more than one technique (6 with electron microscopy + NTA [29,30,31,32,33,34], 3 with electron microscopy + DLS [35,36,37], and 3 with electron microscopy + NTA + DLS [38,39]). Only 9 papers analyzed the electrical charge of EVs, of which 7 used DLS [31,36,37,38,39,42,45] and 2 used NTA [84,85]. The quantity of EVs produced was examined in 18 articles, of which 14 used NTA [31,33,38,39,72,73,74,76,77,79,83,87,88,89], 2 used TRSP [49,50], 1 used flow cytometry [45], and 1 used spectrophotometry [51]. Detailed information on the numerical data of the above-presented results can be found in Table S1. Abbreviations: DLS, dynamic light scattering; NTA, nanoparticle tracking analysis; TRSP, tunable resistive pulse sensing.