Chitosan immobilization on bio-mof nanostructures: a biocompatible ph-responsive nanocarrier for doxorubicin release in treatment of breast cancer

Reza Abazari,1 Ali reza mahjoub,2,*

1. Department of Chemistry, Tarbiat Modares University, P.O. Box 14115–175, Tehran, Iran
2. Department of Chemistry, Tarbiat Modares University, P.O. Box 14115–175, Tehran, Iran

Abstract

Introduction

One of the current research areas of medicinal chemistry is devoted to the development of manageable and targeted drug delivery systems to deliver effective doses of medicines to the targets of interest and avoid the intrinsic drawbacks of traditional therapeutic drugs. another example of inorganic drug delivery tools refers to metal-organic frameworks (mofs), which have received a great deal of attention due to their huge surface area, adjustable pore size, functionalizability, biological inertness and adjustable properties. to solve the solubility issue of bio-mofs, composites of bio-mofs and polymers, such as chitosan (cs), can be employed. cs is a multifunctional natural polysaccharide that is comprised of the β-(1,4)-linked glucosamine and n-acetyl glucosamine units. this polymer is highly biodegradable, bioavailable and nontoxic, and possesses many important medicinal properties. moreover, it can be converted to soluble polycationic salts or other derivatives to produce films, fibers, hydrogels and other agents with suitable traits. as combining both bio-mof and cs with an appropriate material can help to surpass the limitations of their application in drug delivery, this study proposes combining bio-mof and cs with each other to obtain their desirable properties and overcome their disadvantages.

Methods

Dox was considered as a model drug for the drug-loading and release tests. the two ph values of 6.8 and 7.4 were used to simulate the conditions of cancerous and healthy cells, respectively. mtt assay was performed to investigate cell viability. separate samples of the mcf-7 cells were incubated in solutions of free dox, pure cs/bio-mof and dox@cs/bio-mof for 12 h.

Results

The ft-ir spectra of the samples obtained through synthesizing cs/bio-mof from the pure bio-mof, along with the spectrum of cs, were recorded over the range of 400 to 4000 cm-1 to verify the presence of cobalt and adenine bonds and the other functional groups. pxrd analysis was employed to determine the crystallographic properties of the synthesized samples over the 2θ range of 5 to 70º. the zeta potential of the prepared nanocarrier was measured as a function of ph. at ph 5, the zeta potential of cs/bio-mof is +33.0 mv due to the cationic nature of the polysaccharide chains of cs whereas the value of zeta potential declines to +2.4 mv at ph 7 as an outcome of cs deprotonation. application of uv/vis spectrophotometry determined that the dlc and dle parameters of the cs/bio-mof carrier are 48.1% and 92.5% while the dlc and dle values of the bio-mof carrier are 39% and 76%, respectively. results reveal the dramatic effect of the ph-responsive swelling and contracting mechanism of the cs chains on dox release. cell viability in the presence of different concentrations of free dox and dox@cs/bio-mof was investigated by performing the mtt assay on the mcf-7 cell line in acidic media (ph 6.8). according to the results of mcf-7 cell viability, the 50% maximal inhibitory concentration (ic50) of dox@cs/bio-mof is 3.125 µg ml-1 while the ic50 value of free dox is 25 µg ml-1. based on the results, the mcf-7 cells exposed to dox@cs/bio-mof experience a significant increase in the percentage of apoptosis (27.34%) compared with the cells exposed to just free dox (12.21%). in other words, the flow cytometry results imply that dox@cs/bio-mof triggers a substantially higher extent of apoptosis in the mcf-7 cells relative to free dox. the endocytosis capacity of the carrier was determined by incubating the mcf–7 cells with the dox@cs/bio-mofs for 6 and 12 h in the dark and following localization of the released dox molecules in the cells’ nuclei by the means of the dapi fluorescent nuclear marker. these emissions are observed after both incubation times and signify the significant endocytosis capacity of the cs/bio-mof carrier. these results approve that the dox@cs/bio-mofs can diffuse into cytoplasm and release dox, in addition to verifying that the released dox molecules can reach the nuclei of cancerous cells to pose their anticancer effect.

Conclusion

This study immobilized chitosan onto a biological metal-organic framework to create a ph-responsive system (cs/bio-mof) for controlled drug delivery to cancerous cells. throughout the study, optical microscopy, mtt assay, fluorescence microscopy and the trypan blue test were used to determine the in vitro cytotoxicity of the carrier against mcf-7 cells.

Keywords

bio-mof nanostructures, ph-responsive, breast cancer, doxorubicin.