title: Thiolated nanocarriers for oral delivery of hydrophilic macromolecular drugs.
abstract: It was the aim of this study to investigate the effect of unmodified as well as thiolated anionic poly(acrylic acid) (PAA) and cationic chitosan (CS) utilized in free-soluble form and as nanoparticulate system on the absorption of the hydrophilic compound FD4 across intestinal epithelial cell layer with and without a mucus layer. Modifications of these polymers were achieved by conjugation with cysteine to PAA (PAA-Cys) and thioglycolic acid to CS (CS-TGA). Particles were prepared via ionic gelation and characterized based on their amount of thiol groups, particle size and zeta potential. Effects on the cell layer concerning absorption enhancement, transepithelial electrical resistance (TEER) and cytotoxicity were investigated. Permeation enhancement was evaluated with respect to in vitro transport of FD4 across Caco-2 cells, while mucoadhesion was indirectly examined in terms of adsorption behaviour when cells were covered with a mucus layer. Lyophilized particles displayed around 1000 μmol/g of free thiol groups, particle sizes of less than 300 nm and a zeta potential of 18 mV (CS-TGA) and -14 mV (PAA-Cys). Cytotoxicity studies confirmed that all polymer samples were used at nontoxic concentrations (0.5% m/v). Permeation studies revealed that all thiolated formulations had pronounced effects on the paracellular permeability of mucus-free Caco-2 layers and enhanced the permeation of FD4 3.0- to 5.3-fold. Moreover, polymers administered as particles showed a higher permeation enhancement than their corresponding solutions. However, the absorption-enhancing effect of each thiolated formulation was significantly (p<0.05) reduced when cells were covered with mucus layer. In addition, all formulations were able to decrease the TEER of the cell layer significantly (p<0.05). Therefore, both thiolated polymers as nanoparticulate delivery systems represent a promising tool for the oral administration of hydrophilic macromolecules.
authors.affiliation: University of Innsbruck, Institute of Pharmacy/Pharmaceutical Technology, CCB-Centrum of Chemistry and Biomedicine, Innrain 80-82, 6020 Innsbruck, Austria.
authors.forename: S
authors.initials: S
authors.lastname: Dünnhaupt
authors.affiliation: University of Innsbruck, Institute of Pharmacy/Pharmaceutical Technology, CCB-Centrum of Chemistry and Biomedicine, Innrain 80-82, 6020 Innsbruck, Austria.
authors.forename: J
authors.initials: J
authors.lastname: Barthelmes
authors.affiliation: University of Innsbruck, Institute of Pharmacy/Pharmaceutical Technology, CCB-Centrum of Chemistry and Biomedicine, Innrain 80-82, 6020 Innsbruck, Austria.
authors.forename: S
authors.initials: S
authors.lastname: Köllner
authors.affiliation: Faculty of Pharmaceutical Sciences, Khon Kaen University, Khon Kaen 40002, Thailand.
authors.forename: D
authors.initials: D
authors.lastname: Sakloetsakun
authors.affiliation: Department of Pharmacy, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad 54320, Pakistan.
authors.forename: G
authors.initials: G
authors.lastname: Shahnaz
authors.affiliation: Medical University of Innsbruck, Department of Experimental Urology, Anichstrasse 35, 6020 Innsbruck, Austria.
authors.forename: A
authors.initials: A
authors.lastname: Düregger
authors.affiliation: University of Innsbruck, Institute of Pharmacy/Pharmaceutical Technology, CCB-Centrum of Chemistry and Biomedicine, Innrain 80-82, 6020 Innsbruck, Austria. Electronic address: Andreas.Bernkop@uibk.ac.at.
authors.forename: A
authors.initials: A
authors.lastname: Bernkop-Schnürch
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D000284:Administration, Oral; D018938:Caco-2 Cells; D002470:Cell Survival / Q000187:drug effects; D048271:Chitosan / Q000737:chemistry; D003911:Dextrans / Q000737:chemistry / Q000494:pharmacology*; D004337:Drug Carriers / Q000737:chemistry*; D016503:Drug Delivery Systems; D004847:Epithelial Cells / Q000187:drug effects; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D007422:Intestines / Q000187:drug effects; D046911:Macromolecular Substances / Q000737:chemistry / Q000494:pharmacology; D015394:Molecular Structure; D053758:Nanoparticles / Q000737:chemistry*; D013329:Structure-Activity Relationship; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D000180:Acrylic Resins; D003911:Dextrans; D004337:Drug Carriers; D046911:Macromolecular Substances; D013438:Sulfhydryl Compounds; C015219:fluorescein isothiocyanate dextran; C006903:carbopol 940; D048271:Chitosan; D016650:Fluorescein-5-isothiocyanate
keywords: Adhesion; Chitosan (PubChem CID: CID 21896651); Cytotoxic effects; Dithionitrobenzoic acid (PubChem CID: 6254); Nanoparticles; Permeation enhancement; Polymer synthesis; Sodium borohydride (PubChem CID: 22959485); Thiazolyl blue tetrazolium bromide (MTT) (PubChem CID: 64965); Thioglycolic acid (PubChem CID: 1133); l-Cysteine hydrochloride (PubChem CID: 60960)