Complexation of anthracene with folic acid studied by FTIR and UV spectroscopies

Formation of polydopamine nanofibers with the aid of folic acid

Polydopamine (PDA) generated by the oxidative self-polymerization of dopamine shows great potential for surface modification. Observed PDA nanostructures are nanoparticles and thin films. The formation mechanism of PDA is still unclear; thus, the manipulation of PDA nanostructures is a big challenge. In this study, we first demonstrated that folic acid shows a dramatic effect on the PDA nanostructure: New aggregated nanostructures of PDA, nanobelts and nanofibers, were generated in a dopamine/folic acid system. We hypothesized that folic acid may be involved in the stacking of protomolecules of PDA by π-π interactions and hydrogen bonding. Herein we describe the first experimental strategy to manipulate the aggregation of PDA by using small molecules. This study not only provides a new method for generating PDA nanofibers, which are proposed bioorganic electronic materials, but also a possible way to understand the formation mechanism of PDA and its analogues in nature, melanins.

Characterization of ZnO nanoparticles grown in presence of folic acid template

Background

ZnO nanoparticles (grown in the template of folic acid) are biologically useful, luminescent material. It can be used for multifunctional purposes, e.g., as biosensor, bioimaging, targeted drug delivery and as growth promoting medicine.

Methods

Sol–gel chemical method was used to develop the uniform ZnO nanoparticles, in a folic acid template at room temperature and pH ~ 7.5. Agglomeration of the particles was prevented due to surface charge density of folic acid in the medium. ZnO nanoparticle was further characterized by different physical methods.

Results

Nanocrystalline, wurtzite ZnO particles thus prepared show interesting structural as well as band gap properties due to capping with folic acid.

Conclusions

A rapid, easy and chemical preparative method for the growth of ZnO nanoparticles with important surface physical properties is discussed. Emphatically, after capping with folic acid, its photoluminescence properties are in the visible region. Therefore, the same can be used for monitoring local environmental properties of biosystems.

Weak interactions between folate and osmolytes in solution

Previous osmotic stress studies on the role of solvent in two structurally unrelated dihydrofolate reductases (DHFRs) found weaker binding of dihydrofolate (DHF) to either enzyme in the presence of osmolytes. To explain these unusual results, weak interactions between DHF and osmolytes were proposed, with a competition between osmolyte and DHFR for DHF. High osmolyte concentrations will inhibit binding of the cognate pair. To evaluate this hypothesis, we devised a small molecule approach. Dimerization of folate, monitored by nuclear magnetic resonance, was weakened 2-3-fold upon addition of betaine or dimethyl sulfoxide (DMSO), supporting preferential interaction of either osmolyte with the monomer (as it possesses a larger surface area). Nuclear Overhauser effect (NOE) spectroscopy experiments found a positive NOE for the interaction of the C3'/C5' benzoyl ring protons with the C9 proton in buffer; however, a negative NOE was observed upon addition of betaine or DMSO. This change indicated a decreased tumbling rate, consistent with osmolyte interaction. Osmotic stress experiments also showed that betaine, DMSO, and sucrose preferentially interact with folate. Further, studies with the folate fragments, p-aminobenzoic acid and pterin 6-carboxylate, revealed interactions for both model compounds with betaine and sucrose. In contrast, DMSO was strongly excluded from the pterin ring but preferentially interacted with the p-aminobenzoyl moiety. These interactions are likely to be important in vivo because of the crowded conditions of the cell where weak contacts can more readily compete with specific binding interactions.

Morphological properties of nanoporous folic acid materials and in vitro assessment of their biocompatibility

Background: Mesoporous silica-based particles are of potential interest for the development of novel therapeutic targeted delivery vehicles. Their ability to load and release large quantities of active pharmaceutical products with varying properties, combining controlled and targeted release functions make them unique amongst nanotechnology-based carrier systems. Materials & methods: In this study, nanoporous folic acid-templated materials (NFM-1) were prepared and the synthetic strategies for the control of textural and morphology properties of NFM-1 are described. The potential biocompatibility of NFM-1 particles with different morphology (gyroid shaped, fibers and rod-shaped) was assessed using a panel of human cell lines. Results: The results reveal that NFM-1 morphology has an impact on cell viability such that particles showing higher aspect ratios possess increased cytotoxicity. Conclusion: These studies provide useful information for the development of novel mesoporous materials for biomedical applications, including cell-specific drug delivery.

Original submitted: 12 April 2011; Revised submitted: 25 May 2011