Preparation of avidin-labelled gelatin nanoparticles as carriers for biotinylated peptide nucleic acid (PNA)

Incorporation of biodegradable nanoparticles into human airway epithelium cells-in vitro study of the suitability as a vehicle for drug or gene delivery in pulmonary diseases

PURPOSE

Nanoparticles are able to enhance drug or DNA stability for purposes of optimised deposition to targeted tissues. Surface modifications can mediate drug targeting. The suitability of nanoparticles synthesised out of porcine gelatin, human serum albumin, and polyalkylcyanoacrylate as drug and gene carriers for pulmonary application was investigated in vitro on primary airway epithelium cells and the cell line 16HBE14o-.

METHODS

The uptake of nanoparticles into these cells was examined by confocal laser scan microscopy (CLSM) and flow cytometry (FACS). Further the cytotoxicity of nanoparticles was evaluated by an LDH-release-test and the inflammatory potential of the nanoparticles was assessed by measuring IL-8 release.

RESULTS

CLSM and FACS experiments showed that the nanoparticles were incorporated into bronchial epithelial cells provoking little or no cytotoxicity and no inflammation as measured by IL-8 release.

CONCLUSIONS

Based on their low cytotoxicity and the missing inflammatory potential in combination with an efficient uptake in human bronchial epithelial cells, protein-based nanoparticles are suitable drug and gene carriers for pulmonary application.

Signal peptide mimics conjugated to peptide nucleic acid: a promising solution for improving cell membrane permeability

The specific binding ability and biostability of PNA (peptide nucleic acid) with DNA or RNA make PNA not only a good tool for the studies of molecular biology but also the candidate for gene-targeting drugs. However, the main obstacle for its potential usage as a therapeutic is the low cell uptake caused by the poor cell membrane permeability. In this paper the hydrophobic pentadecapeptide and two signal peptide mimics, hexa- and decapeptides ending with a positively charged amino acid, were proposed as the linked carrier for the transportation of PNA T10 through the cell membrane; stable spin label was coupled to the peptide-PNA conjugate so that the ESR measurements can be used for the assessment of their transmembrane movements. The syntheses of spin-labeled peptide-PNA conjugates were carried out on MBHA resin with Boc strategy. The cell membrane permeability of the spin-labeled conjugates of peptides and PNA can be determined with ESR, during the incubation of erythrocyte with the samples. According to ESR measurements, the three conjugates exhibit enhanced uptake into erythrocytes. The hexa- and decapeptide-modified PNA showed suitable water solubility. The peptide-PNA conjugates retained their binding ability to complementary DNA. The results suggest that peptide modification of PNA might be a promising solution for improving cell membrane permeability toward PNA.

Polymeric nanogels produced via inverse microemulsion polymerization as potential gene and antisense delivery agents

Polymeric nanogel vectors were developed for cellular gene and antisense delivery. Inverse microemulsion polymerization was utilized to synthesize biocompatible nanogels with controlled size, morphology, and composition. The chemical composition, size, polydispersity, stability, and swelling behavior of the nanogels were investigated by NMR, light scattering, transmission electron microscopy, and atomic force microscopy. The cell viability, uptake, and physical stability of nanogel-DNA complexes were evaluated under physiological conditions. Monodisperse nonionic and cationic nanogels were produced with controllable sizes ranging from 40 to 200 nm in diameter. The nanogels demonstrated extended stability in aqueous media and exhibited low toxicity in cell culture. Cationic nanogels formed monodisperse complexes with oligonucleotides and showed enhanced oligonucleotide uptake in cell culture. The nanogels synthesized in this study demonstrate potential utility as carriers of oligonucleotides and DNA for antisense and gene delivery.

Preparation of surface modified protein nanoparticles by introduction of sulfhydryl groups

The objective of the present study was to establish several methods for the introduction of thiol groups onto the surface of human serum albumin (HSA) nanoparticles. Besides the epsilon-amino groups of lysine, the carboxyl groups of asparaginic and glutaminic acid, and the carbonyl groups of the cross-linker glutaraldehyde, sulfhydryl groups are possible targets for the covalent linkage of drugs to particle surfaces. In principle, the thiol groups were introduced by the reaction with dithiotreitol (DDT) or 2-iminothiolane, by quenching reactive aldehyde residues with cystaminiumdichloride or by coupling L-cysteine and cystaminiumdichloride by the aqueous carbodiimide reaction. The resulting nanoparticulate systems were characterised concerning the number of available sulfhydryl groups, particle size and particle density. It was shown, that by variation of the reaction conditions, e.g., the concentration of the coupling reagent or the sulfhydryl containing component as well as the reaction time, the proposed methods enabled the preparation of HSA nanoparticles with a well defined surface characteristic. Stability studies showed that the introduced thiol groups were relatively stable and lost their reactivity with a half-life of 28.2 days independently of the method used for the sulfhydryl group introduction. Besides the quantification of free sulfhydryl groups the covalent attachment of cystaminiumdichloride by the carbodiimide reaction was used to calculate the amount of free carboxyl groups on the surface of the nanoparticles. The toxicity of the modified nanoparticles was evaluated in cell culture experiments.