DNA protection from extracapsular nucleases, within chitosan- or poly-L-lysine-coated alginate beads

Quong, D.; Neufeld, Ronald J.

doi:10.1002/(sici)1097-0290(19981005)60:1<124::aid-bit14>3.0.co;2-q

Cited by 82 publications

(37 citation statements)

References 28 publications

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“…However, in a study (Quong & Neufeld 1998) involving the immobilisation of DNA within an alginate gel matrix coated with chitosan, almost total hydrolysis of DNA was observed in alginate beads following exposure to nucleases and less than 1 % of the total double stranded DNA remained unhydrolysed within chitosan beads corresponding with an increase in DNA residuals. It was further noted that chitosan membranes did not offer sufficient protection against DNase diffusion.…”

Section: Colon Targetingmentioning

confidence: 99%

Chitosan: some pharmaceutical and biological aspects - an update

Singla

Chawla

2001

Journal of Pharmacy and Pharmacology

705

363

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Chitosan, a natural polysaccharide, is being widely used as a pharmaceutical excipient. It is obtained by the partial deacetylation of chitin, the second most abundant natural polymer.Chitosan comprises a series of polymers varying in their degree of deacetylation, molecular weight, viscosity, pKa etc. The presence of a number of amino groups permit chitosan to chemically react with anionic systems, thereby resulting in alteration of physicochemical characteristics of such combinations.Chitosan has found wide applicability in conventional pharmaceutical devices as a potential formulation excipient, some of which include binding, disintegrating and tablet coating properties. The polymer has also been investigated as a potential adjuvant for swellable controlled drug delivery systems. Use of chitosan in novel drug delivery as mucoadhesive, gene and peptide drug administration via the oral route as well as its absorption enhancing effects have been explored by a number of researchers.Chitosan exhibits myriad biological actions, namely hypocholesterolemic, antimicrobial and wound healing properties. Low toxicity coupled with wide applicability makes it a promising candidate not only for the purpose of drug delivery for a host of drug moieties (antiinflammatories, peptides etc.) but also as a biologically active agent.It is the endeavour of the present review to provide an insight into the biological and pharmaceutical profile of chitosan. Various investigations carried out recently are reported, although references to research performed on chitosan prior to the recent reviews have also been included, where appropriate.

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Section: Colon Targetingmentioning

confidence: 99%

Chitosan: some pharmaceutical and biological aspects - an update

Singla

Chawla

2001

Journal of Pharmacy and Pharmacology

705

363

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“…It is a linear copolymer composed of 1,4-linked-␤-d-mannuronic acid and ␣-l-guluronic acid residues that gels in the presence of divalent cations, such as calcium, due to the stacking of guluronic acid (G) blocks with the formation of "egg-box" calcium linked junctions (Martinsen et al, 1989). Alginate microspheres have been used for the encapsulation of a wide variety of biologically active agents, including proteins (Coppi et al, 2002), enzymes (Boadi and Neufeld, 2001), antibodies (Albarghouthi et al, 2000), cells (Klinkenberg et al, 2001) and DNA (Quong and Neufeld, 1998), due to the relatively mild crosslinking conditions of preparation. In particular, calcium-alginate microspheres were used to encapsulate insulin by using an extrusion process (Gray and Dowsett, 1988) and an encapsulation efficiency of 65% was obtained.…”

Section: Introductionmentioning

confidence: 99%

Alginate microspheres prepared by internal gelation: Development and effect on insulin stability

Silva

Ribeiro

Figueiredo

et al. 2006

International Journal of Pharmaceutics

187

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Recombinant human insulin was encapsulated within alginate microspheres by the emulsification/internal gelation technique with the objective of preserving protein stability during encapsulation procedure. The influence of process and formulation parameters was evaluated on the morphology and encapsulation efficiency of insulin. The in vitro release of insulin from microspheres was studied under simulated gastrointestinal conditions and the in vivo activity of protein after processing was assessed by subcutaneous administration of extracted insulin from microspheres to streptozotocin-induced diabetic rats. Microspheres mean diameter, ranging from 21 to 287 m, decreased with the internal phase ratio, emulsifier concentration, mixer rotational speed and increased with alginate concentration. Insulin encapsulation efficiency, near 75%, was not affected by emulsifier concentration, mixer rotational speed and zinc/insulin hexamer molar ratio but decreased either by increasing internal phase ratio and calcium/alginate mass ratio or by decreasing acid/calcium molar ratio and alginate concentration. A high insulin release, above 75%, was obtained at pH 1.2 and under simulated intestinal pH a complete dissolution of microspheres occurred. Extracted insulin from microspheres decreased hyperglycemia of diabetic rats proving to be bioactive and showing that encapsulation in alginate microspheres using the emulsification/internal gelation is an appropriate method for protein encapsulation.

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“…58 The ability of chitosan-based nanoparticles to protect siRNA mimicking dsODN sequences was assessed using a DNAse I protection assay against different chitosan formulations complexed with dsODN-RecQL1 or dsODN-ApoB. Upon incubatio n Figure 3A-D).…”

Section: Nanoparticle Protection Assaymentioning

confidence: 99%

Low molecular weight chitosan nanoparticulate system at low N:P ratio for nontoxic polynucleotide delivery

Alameh¹,

DeJesus²,

Jean³

et al. 2012

IJN

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Chitosan, a natural polymer, is a promising system for the therapeutic delivery of both plasmid DNA and synthetic small interfering RNA. Reports attempting to identify the optimal parameters of chitosan for synthetic small interfering RNA delivery were inconclusive with high molecular weight at high amine-to-phosphate (N:P) ratios apparently required for efficient transfection. Here we show, for the first time, that low molecular weight chitosan (LMW-CS) formulations at low N:P ratios are suitable for the in vitro delivery of small interfering RNA. LMW-CS nanoparticles at low N:P ratios were positively charged (ζ-potential ∼20 mV) with an average size below 100 nm as demonstrated by dynamic light scattering and environmental scanning electron microscopy, respectively. Nanoparticles were spherical, a shape promoting decreased cytotoxicity and enhanced cellular uptake. Nanoparticle stability was effective for at least 20 hours at N:P ratios above two in a slightly acidic pH of 6.5. At a higher basic pH of 8, these nanoparticles were unravelled due to chitosan neutralization, exposing their polynucleotide cargo. Cellular uptake ranged from 50% to 95% in six different cell lines as measured by cytometry. Increasing chitosan molecular weight improved nanoparticle stability as well as the ability of nanoparticles to protect the oligonucleotide cargo from nucleases at supraphysiological concentrations. The highest knockdown efficiency was obtained with the specific formulation 92-10-5 that combines sufficient nuclease protection with effective intracellular release. This system attained .70% knockdown of the messenger RNA, similar to commercially available lipoplexes, without apparent cytotoxicity. Contrary to previous reports, our data demonstrate that LMW-CS at low N:P ratios are efficient and nontoxic polynucleotide delivery systems capable of transfecting a plethora of cell lines.

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DNA protection from extracapsular nucleases, within chitosan- or poly-L-lysine-coated alginate beads

Cited by 82 publications

References 28 publications

Chitosan: some pharmaceutical and biological aspects - an update

Chitosan: some pharmaceutical and biological aspects - an update

Alginate microspheres prepared by internal gelation: Development and effect on insulin stability

Low molecular weight chitosan nanoparticulate system at low N:P ratio for nontoxic polynucleotide delivery

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