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Abstract
Background:
The gastroretentive drug delivery system is an effective administration route, which can improve the bioavailability of the drug and the therapeutic effect by prolonging the release time of the drug and controlling the release rate in the stomach.
Methods:
Inspired by the excellent adhesion properties of mussel protein, we prepared novel catechol-grafted chitosan alginate/barium sulfate microcapsules (Cat-CA/BS MCs) with mucoadhesive properties and computed tomography (CT) imaging function for gastric drug delivery. First, barium sulfate nanoclusters used as CT contrast agent were synthesized in situ in the Cat-CA/BS MCs through a one-step electronic spinning method. Next, catechol-grafted chitosan as the mucoadhesive moiety was coated on the surface of Cat-CA/BS MCs by polyelectrolyte molecule self-assembly.
Results:
The prepared Cat-CA/BS MCs could effectively retained in the stomach for 48 hours and successively released ranitidine hydrochloride, which could be used for the treatment of gastric ulcer. Cat-CA/BS MCs exhibited superior CT contrast imaging properties for real-time tracking in vivo after oral administration.
Conclusion:
These findings demonstrate that Cat-CA/BS MCs serving as multifunctional oral drug carriers possess huge potential in gastroretentive drug delivery and non-invasive visualization.
Acknowledgments
This work was supported by the Jiangsu 333 High-Level Talents Training Project (number BRA2017145), Six Talent Peaks Project in Jiangsu Province (WSN-281), Key Talents of Medical Science in Jiangsu Province Project (QNRC2016444), the China Postdoctoral Science Foundation (2015M571705), and Zhenjiang Key Research and Development Program–Social Development (SH2016027).
Disclosure
The authors report no conflicts of interest in this work.
Supplementary materials
Experimental section
1. Materials and characterization
Materials
Fluorescein 5(6)-isothiocyanate and rhodamine B were purchased from Aladdin Industrial Inc.
Characterization
Laser scanning confocal microscopy (LSCM) was carried out on an FV1200 (Japan).
2. Synthesis of FITC-alginate and rhodamine B–chitosan
100 mL of 2.5% sodium alginate solution, pH adjusted to 8.5 with 1 N sodium hydroxide; 100 μL of FITC (1 mg/mL) solution dissolved in DMSO was added, then incubated at 40°C for 1 hour, followed by dialysis against light (molecular weight cut-off: 1,000) for 2 days.
1% chitosan solution was dissolved in 0.1 mol/L acetic acid; 50 μL of rhodamine B (0.5 mg/mL) solution dissolved in DMSO was added, then incubated for 30 minutes at room temperature with stirring, followed by dialysis against light (molecular weight cut-off: 1,000) for 2 days.
3. Characteristics of multiple coatings on the MC shell
FITC-alginate and rhodamine B–chitosan were scanned using a laser confocal microscope and the multilayer coating on the outer wall of the MCs was localized by fluorescence.
Figure S1 Effect of sodium sulfate at different concentrations from 0.1% to 1.0% on the morphology of catechol 27–chitosan alginate/barium sulfate microcapsules.
Figure S2 Laser scanning confocal microscopy images of a wall section of catechol-27–chitosan/barium sulfate microcapsules under different excitation wavelengths. Abbreviation: FITC, fluorescein isothiocyanate.
Figure S3 Relative retention rates of A/BS MCs, CA/BS MCs, and Cat27-CA/BS MCs (n=5 per group) on the mucin-coated surface after PBS washing.Note: *Significant differences.
Abbreviations: A/BS MCs, alginate/barium sulfate microcapsules; CA/BS MCs, chitosan alginate/barium sulfate microcapsules; Cat27-CA/BS MCs, catechol-27–chitosan alginate/barium sulfate microcapsules.
Figure S4 Macroscopic appearance and area of acetic acid-induced gastric ulcer after different treatments: normal; acetic acid; alginate/barium sulfate microcapsules (A/BS MCs); ranitidine hydrochloride (RH); ranitidine hydrochloride–chitosan alginate/barium sulfate microcapsules (RH-CA/BS MCs); and ranitidine hydrochloride–catechol-27–chitosan alginate/barium sulfate microcapsules (RH-Cat27-CA/BS MCs).
