Polymer/Metal Organic Framework (MOF) Nanocomposites for Biomedical Applications.

The utilization of polymer/metal organic framework (MOF) nanocomposites in various biomedical applications has been widely studied due to their unique properties that arise from MOFs or hybrid composite systems. This review focuses on the types of polymer/MOF nanocomposites used in drug delivery and imaging applications. Initially, a comprehensive introduction to the synthesis and structure of MOFs and bio-MOFs is presented. Subsequently, the properties and the performance of polymer/MOF nanocomposites used in these applications are examined, in relation to the approach applied for their synthesis: (i) non-covalent attachment, (ii) covalent attachment, (iii) polymer coordination to metal ions, (iv) MOF encapsulation in polymers, and (v) other strategies. A critical comparison and discussion of the effectiveness of polymer/MOF nanocomposites regarding their synthesis methods and their structural characteristics is presented.

Use of mesoporous cellular foam (MCF) in preparation of polymeric microspheres for long acting injectable release formulations of paliperidone antipsychotic drug.

In this study, high surface area mesoporous silica foam with cellular pore morphology (MCF) was used for injectable delivery of paliperidone, an antipsychotic drug used in patients suffering from bipolar disorder. The aim was to enhance paliperidone solubility and simultaneously to prepare long active intractable microspheres. For this reason paliperidone was first loaded in MCF silica, and the whole system was further encapsulated into PLA and PLGA 75/25w/w copolymer in the form of microspheres. It was found that paliperidone, after its adsorption into MCF, was transformed in its amorphous state, thus leading to enhanced in vitro dissolution profile. Furthermore, incorporation of the drug-loaded MCF to polymeric microparticles (PLA and PLGA) prolonged the release time of paliperidone from 10 to 15days.

PLGA/SBA-15 mesoporous silica composite microparticles loaded with paclitaxel for local chemotherapy.

In this work, high surface area mesoporous silica (SBA-15) was loaded with paclitaxel (taxol, PTX) and was further entrapped into poly(lactic acid-co-glycolic acid) (PLGA) microparticles (MPs). A modified solvent evaporation-emulsion method was used in order to formulate the composite microparticles with sizes of 8-12µm. PTX loaded SBA-15 as well as the PLGA/PTX-SBA-15 composites were characterized in terms of their morphology, crystal structure and thermal properties. Drug content, loading efficiency, particle size and the in-vitro drug release kinetics of the PLGA/PTΧ-SBA-15 microspheres were also investigated. The in vitro release studies were carried out using Simulated Body Fluid (SBF) at 37°C revealing that the prepared formulations present higher dissolution rate than pure PTX and sustained pattern which is ideal for anticancer carriers. Modeling and data analysis of the in vitro drug release was also investigated. It was also shown that all microparticles have low cytotoxicity in HUVE cells. Finally, it was found that drug loaded microparticles are very effective in Human Cervical Adenocarcinoma (HeLa) cells.

Evaluating the effects of crystallinity in new biocompatible polyester nanocarriers on drug release behavior.

Four new polyesters based on 1,3-propanediol and different aliphatic dicarboxylic acids were used to prepare ropinirole HCl-loaded nanoparticles. The novelty of this study lies in the use of polyesters with similar melting points but different degrees of crystallinity, varying from 29.8% to 67.5%, as drug nanocarriers. Based on their toxicity to human umbilical vein endothelial cells, these aliphatic polyesters were found to have cytotoxicity similar to that of polylactic acid and so may be considered as prominent drug nanocarriers. Drug encapsulation in polyesters was performed via an emulsification/solvent evaporation method. The mean particle size of drug-loaded nanoparticles was 164-228 nm, and the drug loading content was 16%-23%. Wide angle X-ray diffraction patterns showed that ropinirole HCl existed in an amorphous state within the nanoparticle polymer matrices. Drug release diagrams revealed a burst effect for ropinirole HCl in the first 6 hours, probably due to release of drug located on the nanoparticle surface, followed by slower release. The degree of crystallinity of the host polymer matrix seemed to be an important parameter, because higher drug release rates were observed in polyesters with a low degree of crystallinity.

Nanoencapsulation of a water soluble drug in biocompatible polyesters. Effect of polyesters melting point and glass transition temperature on drug release behavior.

Five polyesters based on 1,3-propanediol or ethylene glycol and an aliphatic dicarboxylic acid were used for the preparation of Ropinirole HCl-loaded nanoparticles. The advantage of the present study is that the used polyesters - as well as poly(lactic acid) (PLA) - have similar degree of crystallinity but different melting points, varying from 46.7 to 166.4°C. Based on polymer toxicity on HUVEC, the biocompatibility of these aliphatic polyesters was found comparable to that of PLA and thus the studied polyesters could be used as drug carriers. Drug encapsulation in polyesters was performed via emulsification/solvent evaporation method. Particle size of drug-loaded nanoparticles was between 140 and 190 nm, as measured by light scattering. Drug loading content for all the polyesters varies between 10 and 16% and their entrapment efficiency is relatively high (32-48%). WAXD patterns of nanoparticles show that Ropinirole HCl lies in amorphous state within polymer matrices. Drug release diagrams reveal that the higher percentage of Ropinirole HCl is released during the first 6h after its insertion in the dissolution medium. Fast release rates of the drug are attributed to high hydrophilicity of Ropinirole HCl. Melting point (T(m)) and glass transition temperature (T(g)) of the host polymer matrices seem to be important parameters, since higher drug release rates are observed in polyesters with low T(m) and T(g).

Correlation between chemical and solid-state structures and enzymatic hydrolysis in novel biodegradable polyesters. The case of poly(propylene alkanedicarboxylate)s.

A series of seven fast-biodegrading aliphatic polyesters were prepared from 1,3-propanediol and aliphatic diacids with increasing number of methylene units (x). Melting points decreased from PPSu to PPAd and then increased again to PPAz and PPSeb. Crystallization rates and thermal stability increased steadily with increasing x. Glass transition temperatures decreased steadily to PPPim and subsequently increased. Enzymatic degradation of the polymers in the presence of a mixture of Rhizopus delemar and Pseudomonas cepacia lipases was much faster than that of poly(epsilon-caprolactone). All the polyester specimens were almost disintegrated within 36 h. PPSub exhibited the fastest enzymatic hydrolysis rates, PPAd and PPSuc the slowest.