Preparation, characterization and targeting of micronized 10-hydroxycamptothecin-loaded folate-conjugated human serum albumin nanoparticles to cancer cells

Abstract

Background: The purpose of this study was to develop a method for targeted delivery of 10-hydroxycamptothecin (HCPT)-loaded nanoparticles (NPs) to cancer cells.

Methods: We first used a supercritical antisolvent process to prepare micronized HCPT (nHCPT), and then folate-conjugated human serum albumin (HSA) nHCPT-loaded NPs (FA-HSA-nHCPT-NPs) were prepared using a NP-coated method combined with a desolvation technique. The amount of folate conjugation was 16 μg · mg(-1) HSA.

Results: The particle size of the spherical nHCPT microparticles obtained was 118.5 ± 6.6 nm. The particle size and zeta potential of the FA-HSA-nHCPT-NPs were 233.9 ± 1.2 nm and -25.23 ± 2.98 mV, respectively. The FA-HSA-nHCPT-NPs exhibited a smooth surface and a distinct spherical shape, and the results of differential scanning calorimetry and X-ray diffraction indicated that the FA-HSA-nHCPT-NPs presented in a nanostructured amorphous state. The FA-HSA-nHCPT-NPs showed sustained-release characteristics for 120 hours in vitro, with a drug-loading content of 7.3% and an encapsulating efficiency of 79.1%.

Conclusion: The FA-NPs were effective delivery systems for uptake by SGC7901 cells compared with folate-free NPs. These results suggest that a NP-coated method combined with a desolvation technique is effective for preparing NPs with drugs having poor solubility in water and most organic solvents, using albumin as the wall material. FA-HSA-NPs are a stable delivery system and have the potential for targeted delivery of anticancer drugs.

Keywords: 10-hydroxycamptothecin; desolvation technique; folate; human serum albumin; nanoparticle-coated; targeted delivery.

Figure 1

Schematic process for preparation of micronized 10-hydroxycamptothecin-loaded folate-conjugated human serum albumin nanoparticles. Abbreviations: nHPCT, micronized 10-hydroxycamptothecin; FA-HSA-nHCPT-NPs, micronized 10-hydroxycamptothecin-loaded folate-conjugated human serum albumin nanoparticles.

Figure 2

A) Determination of folate content conjugated with human serum albumin, a) N-hydroxysuccinimide ester of folate, b) tryptic hydrolysis of folate-conjugated human serum albumin nanoparticles, c) tryptic hydrolysis of human serum albumin nanoparticles; the particle size distribution of B) micronized 10-hydroxycamptothecin, C) micronized 10-hydroxycamptothecin-loaded folate-conjugated human serum albumin nanoparticles, D) HSA-nHCPT-NPs; the morphology observation of E) raw hydroxycamptothecin, F) micronized hydroxycamptothecin, G) micronized 10-hydroxycamptothecin-loaded folate-conjugated human serum albumin nanoparticles, and H) human serum albumin-loaded 10-hydroxycamptothecin nanoparticles, by scanning electron microscopy.

Figure 3

A) X-ray diffraction patterns, B) differential scanning calorimetry (DSC) curves, a) raw 10-hydroxycamptothecin, b) micronized 10-hydroxycamptothecin, and c) micronized 10-hydroxycamptothecin-loaded folate-conjugated human serum albumin nanoparticles.

Figure 4

The release profiles of micronized 10-hydroxycamptothecin and micronized 10-hydroxycamptothecin-loaded folate-conjugated human serum albumin nanoparticles in vitro. (▴) Micronized 10-hydroxycamptothecin. (▵) Micronized 10-hydroxycamptothecin-loaded folate-conjugated human serum albumin nanoparticles.

Figure 5

Confocal microscopy results. A549 cells (A and D) and SGC7901 cells (B, C, E, and F) were incubated with fluorescein isothiocyanate-labeled folate-conjugated human serum albumin nanoparticles or human serum albumin nanoparticles at indicated concentrations for four hours at 37°C. A) and B) 0.5 mg·mL⁻¹ human serum albumin nanoparticles. C) 1 mg·mL⁻¹ human serum albumin nanoparticles. D) and E) 0.5 mg·mL⁻¹ folate-conjugated human serum albumin nanoparticles. F) 1 mg·mL⁻¹ folateconjugated human serum albumin nanoparticles.

Figure 6

Schematic process of classical desolvation method.