Effect of surfactants and polymer composition on the characteristics of polyhydroxyalkanoate nanoparticles

Abstract

Background and purpose: Polyhydroxyalkanoates (PHAs) are biodegradable polyesters of bacterial origin that are actively studied as matrices for the preparation of nanoparticulate drug delivery systems. The most significant parameters affecting PHAs nanoparticles (NPs) characteristics are polymer composition and the type of surfactant used to stabilize the emulsion during NPs preparation. However, there are only a few studies in the literature investigating the effect of these factors on the characteristics of PHA NPs.

Experimental approach: Blank poly(3-hydroxybutyrate) (P3HB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P3HBV) NPs were produced and characterized in terms of their size, morphology and zeta potential. Poly(vinyl alcohol) (PVA) with various molecular weights (31-50 and 85-124 kDa), as well as Tween 20 (TW20), Tween 80 (TW80), sodium deoxycholate (SDC) and sodium dodecyl sulphate (SDS) were used as surfactants. For NPs that formed stable aqueous suspensions and had the most desirable characteristics (P3HB/PVA_31-50 and P3HBV/PVA_31-50), hemolytic activity and cytotoxicity to HeLa and C2C12 cells in vitro were determined.

Key results: NPs of both P3HB and P3HBV obtained using PVA with the M _w of 31-50 kDa as a surfactant had regular spherical shape, uniform size distribution, average diameter of about 900 nm and zeta potential of -28.5 and -28.7 mV, respectively. PVA_85-124, TW20 and TW80, as well as SDC and SDS as surfactants, did not show satisfactory results due to suspension gelation, formation of hollow NPs with irregular shape and poor resuspension after washing and freeze-drying, respectively. P3HB/PVA_31-50 and P3HBV/PVA_31-50 NPs did not have hemolytic activity and did not show pronounced cytotoxicity to HeLa and C2C12 cells in the concentration range from 10 to 500 μg mL^-1, so these samples were regarded as safe and biocompatible.

Conclusion: In this study, the effect of various non-ionic and anionic surfactants on the characteristics of P3HB and P3HBV NPs was investigated. PVA_31-50 was found to be effective in producing NPs of both studied polymers with good biocompatibility and favorable characteristics, making them suitable for drug delivery applications. In contrast, other studied surfactants, i.e., PVA_85-124, TW20, TW80, SDC and SDS, require further investigation. The obtained findings may promote the development of novel PHA-based nanomedicines.

Keywords: P3HB; P3HBV; Tween 80; polyvinyl alcohol; sodium deoxycholate; sodium dodecyl sulphate.

Figure 1.

SEM images of the obtained NPs. (A) P3HB/PVA_31-50. (B) P3HBV/PVA_31-50. (C) P3HB/PVA_85-124. (D) P3HBV/PVA_85-124. (E) P3HB/TW20. (F) P3HBV/TW20. (G) P3HB/TW80. (H) P3HBV/TW80. (I) P3HB/SDC. (J) P3HBV/SDC. (K) P3HB/SDS. (L) P3HBV/SDS

Figure 2.

Hemolytic activity of P3HB/PVA_31-50 (A) and P3HBV/PVA_31-50 (B) at different NPs concentrations

Figure 3.

Viability of HeLa (black) and C2C12 (blue) cells treated with P3HB/PVA_31-50 (A) and P3HBV/PVA_31-50 (B) at different NPs concentrations

Figure 4.

Images of HeLa (A, B) and C2C12 (C, D) cells treated with P3HB/PVA_31-50 NPs at different concentrations obtained using fluorescent and optical microscope. Live and dead cells had blue and green fluorescence, respectively. At the concentrations of 10, 50, 100 and 500 μg mL^-1 P3HB/PVA_31-50 NPs covered 8, 21, 55 and more than 90 % of cell monolayer, respectively. Data for P3HBV/PVA_31-50 are not presented