Retraction notice to "Evaluation of the surface chemistry and drug-polymer interaction of semi-crystalline micro-particles for the development of controlled release formulations" [Mater. Sci. Eng. C (2017) 559-567].

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editor in Chief following the internal investigation at the University of Sussex and University of Greenwich. The investigation found that the corresponding author, Dr Mohammed Maniruzzaman, used unpublished experimental data from earlier research projects without securing the necessary permissions and approvals from the University of Greenwich.

Evaluation of the surface chemistry and drug-polymer interaction of semi-crystalline micro-particles for the development of controlled release formulations.

This research work explores the surface chemistry and drug-polymer interaction in the manufactured controlled release micro-particles. Isoniazid (INH) was used as a model anti-tubercular drug while Eudragit® S100 (S100), Eudragit® L100-55 based co-processed Acryl EZE (EZE) and Ethylcellulose ECN10 (ECN10) were used as polymeric carriers. INH containing micro-particles were prepared using a mini spray dryer B-290 (Buchi, Switzerland). The drug polymer ratios were optimized at 1:1 and 1:3 to evaluate the effect of polymers on the release of the drug from the micro-particles. Solid state characterization via SEM and particle size analysis of the manufactured micro-particles showed densely aggregated spherical particles with a mean diameter <10µm. The advanced surface analysis via EDS revealed a homogenous drug distribution on the spray dried micro-particles. The physico-chemical characterization carried out by using DSC and XRPD showed an increase in the amorphicity of the drug during the spray drying process while the chemical elemental analysis via XPS revealed a strong intermolecular interaction between the amine group of the drug and the carboxyl group of the polymers. As expected, the in vitro dissolution study showed a slow release pattern for the highly water soluble drug INH in acidic media (pH1.2) for the first 2h followed by a burst release upon changing the pH to 6.8. It was concluded that emerging spray drying processing can be used as a valuable tool to encapsulate drug for controlled release dosage forms by means of facilitating a possible drug/polymer interaction as outlined by novel XPS analysis.