DNA-coated microcrystals

Protein-coated nanoparticles embedded in films as delivery platforms

Objectives

This work aimed to evaluate the performance of nanoparticle-loaded films based on matrices of polymethacrylates and hydroxypropylmethylcellulose (HPMC) intended for delivery of macromolecules.

Methods

Lysozyme (Lys)-loaded nanoparticles were manufactured by antisolvent co-precipitation. After size, loading efficiency and stability characterization, the selected batch of particles was further formulated into films. Films were characterized for mechanical properties, mucoadhesion, Lys release and activity after manufacture.

Key findings

We found that protein-coated nanoparticles could be obtained in USP phosphate buffer pH 6.8. Particles obtained at pH 6.8 had a z-average of 347.2 nm, a zeta-potential of 21.9 mV and 99.2% remaining activity after manufacture. This formulation was further studied for its application in films for buccal delivery. Films loaded with nanoparticles that contained Eudragit RLPO (ERL) exhibited excellent mechanical and mucoadhesive properties. Due to its higher water-swelling and solubility compared with ERL, the use of HPMC allowed us to tailor the release of Lys from films. The formulation composed of equal amounts of ERL and HPMC revealed a sustained release over 4 h, with Lys remaining fully active at the end of the study.

Conclusions

Mucoadhesive films containing protein-coated nanoparticles are promising carriers for the buccal delivery of proteins and peptides in a stable form.

Lyophilized inserts for nasal administration harboring bacteriophage selective for Staphylococcus aureus: in vitro evaluation

Nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA) poses an infection risk and eradication during hospitalization is recommended. Bacteriophage therapy may be effective in this scenario but suitable nasal formulations have yet to be developed. Here we show that lyophilization of bacteriophages in 1ml of a viscous solution of 1-2% (w/v) hydroxypropyl methylcellulose (HPMC) with/without the addition of 1% (w/v) mannitol, contained in Eppendorf tubes, yields nasal inserts composed of a highly porous leaflet-like matrix. Fluorescently labeled bacteriophage were observed to be homogenously distributed throughout the wafers of the dried matrix. The bacteriophage titer fell 10-fold following lyophilization to 10(8)pfu per insert, then falling a further 100- to 1000-fold over 6 to 12months storage at 4°C. This compares well with a total dose of 6×10(5)pfu in 0.2ml liquid applied into the ear during a recent clinical trial in humans. The residual water content of the lyophilized inserts was reduced upon the addition of mannitol to HPMC, but this did not have any correlation to the lytic activity. Mannitol underwent a transition from its amorphous to crystalline state during exposure of the inserts to increasing relative humidities (as would be experienced in the nose), although this transition was suppressed by higher HPMC concentrations and the presence of buffer containing gelatin and bacteriophages. Our results therefore suggest that lyophilized inserts harboring bacteriophage selective for S. aureus may be a novel means for the eradication of MRSA resident in the nose.

Face-selective decoration of an organic single crystal toward photochemical devices

Face-selective decoration of a single crystal constructed from 1-pyrenemethylammonium chloride by an anionic porphyrin dye is reported. CLSM observations indicated that the {001} face of the single crystal was selectively coated by the anionic porphyrin (TPPS). This novel achievement could be the first step for preparation of multi-component composite materials mediated by anisotropy of organic single crystals toward photochemical devices.