Atomic layer deposition-A novel method for the ultrathin coating of minitablets

Atomic Layer Deposition Coating on the Surface of Active Pharmaceutical Ingredients to Reduce Surface Charge Build-Up

Active pharmaceutical ingredients (APIs) typically consist of solid therapeutic particles that may acquire electrostatic charge during milling and grinding operations. This may result in the agglomeration of particles, thereby reducing the flowability and affecting the homogeneity of the drug formulation. Electrostatic charge build-up may also lead to fire explosions. To avoid charge build-up, APIs are often coated with polymers. In this paper, atomic layer deposition (ALD) using metal oxides such as Al2O3 and TiO2 on APIs, namely, palbociclib and pazopanib HCl, has been utilized to demonstrate a uniform coating that results in a significant reduction in the surface charge of the drug particles. Kelvin probe force microscopy (KPFM) shows a 4-fold decrease in the surface contact potential of uncoated pazopanib HCl (2.3 V) to 0.52 and 0.82 V in TiO2-and Al2O3-coated APIs, respectively. Also, the ζ potential indicated a 4-fold decrease in the surface charge on coating pazopanib HCl, i.e., from -32.9 mV to -7.51 and -8.51 mV in Al2O3 and TiO2, respectively. Surface morphology, thermal stability, dissolution studies, and cytotoxicity of the drug particles after coating were also examined. Thermal analysis indicated no change in the melting temperature (Tm) after coating. ALD coating was found to be uniform and conformal as observed in images obtained from scanning electron microscopy (SEM) and scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS). The rate of dissolution was found to be delayed by the coating, and thus ALD offers slower drug release. Coating APIs with TiO2 and Al2O3 did not induce statistically significant cytotoxicity compared to the uncoated samples. The results presented in this study demonstrate that ALD coating can be used to reduce surface charge build-up and enhance the bulk properties of the drug particles without affecting their physicochemical properties.

Retention of surface structure causes lower density in atomic layer deposition of amorphous titanium oxide thin films

Size effects and structural modifications in amorphous TiO₂ films deposited by atomic layer deposition (ALD) were investigated. As with the previously investigated ALD-deposited Al₂O₃ system we found that the film's structure and properties are strongly dependent on its thickness, but here, besides the significant change in the density of the films there is also a change in their chemical state. The thin near-surface layer contained a significantly larger amount of Ti⁺³ species and oxygen vacancies relative to the sample's bulk. We attribute this change in chemistry to the ALD specific deposition process wherein each different atomic species is deposited in turn, thereby forming a "corundum-like" structure of the near-surface layer resembling that found in the Al₂O₃ system. This, combined with the fact that each deposited layer starts out as a surface layer and maintains the surface structure over the next several following deposition cycles, is responsible for the overall decrease in the film density. This is the first time this effect has been shown in detail for TiO₂, expending the previously discovered phenomenon to a new system and demonstrating that while similar effects occur, they can present in different ways for oxide systems with different structures and symmetries.

Novel graphitic sheets with ripple-like folds as an NCA cathode coating layer for high-energy-density lithium-ion batteries

In this work, novel graphitic sheets with ripple-like folds (GSRFs) are synthesized from cheap resin via a facile route. The obtained GSRFs are used as a cladding layer for LiNi0.8Co0.15Al0.05O2 (NCA) particles to construct a GSRF@NCA composite cathode. Electrochemical testing for GSFR@NCA exhibits better cycling and C-rate performance than those of original NCA. Moreover, the capacity retention (85%) of the full-cell (GSFR@NCA versus graphite) is much higher than that (79%) of the full-cell (NCA versus graphite) after 400 cycles. Most importantly, this approach allows the preparation of GSFR@NCA with highly promising applications as a cathode for high-energy-density lithium-ion batteries, since in this contribution just simple equipment and a precursor with low cost are involved.

Titanium Dioxide Nanoparticles: Prospects and Applications in Medicine

Metallic and metal oxide nanoparticles (NPs), including titanium dioxide NPs, among polymeric NPs, liposomes, micelles, quantum dots, dendrimers, or fullerenes, are becoming more and more important due to their potential use in novel medical therapies. Titanium dioxide (titanium(IV) oxide, titania, TiO₂) is an inorganic compound that owes its recent rise in scientific interest to photoactivity. After the illumination in aqueous media with UV light, TiO₂ produces an array of reactive oxygen species (ROS). The capability to produce ROS and thus induce cell death has found application in the photodynamic therapy (PDT) for the treatment of a wide range of maladies, from psoriasis to cancer. Titanium dioxide NPs were studied as photosensitizing agents in the treatment of malignant tumors as well as in photodynamic inactivation of antibiotic-resistant bacteria. Both TiO₂ NPs themselves, as well as their composites and combinations with other molecules or biomolecules, can be successfully used as photosensitizers in PDT. Moreover, various organic compounds can be grafted on TiO₂ nanoparticles, leading to hybrid materials. These nanostructures can reveal increased light absorption, allowing their further use in targeted therapy in medicine. In order to improve efficient anticancer and antimicrobial therapies, many approaches utilizing titanium dioxide were tested. Results of selected studies presenting the scope of potential uses are discussed in this review.

Nanoshells prepared by atomic layer deposition - Long acting depots of indomethacin

There is a trend in pharmaceutical research and development to develop depot formulations with dosing once weekly, once monthly, or even less frequently. A novel approach to achieve long acting injectable suspensions is to produce dense inorganic nanoshells with atomic layer deposition (ALD) on active pharmaceutical ingredients. Such particles can be suspended in an aqueous vehicle and administered subcutaneously. The purpose of this work was to study the release of a model drug, indomethacin, coated with aluminium oxide nanoshells. Indomethacin was ball-milled to a median particle size of 6 µm. The nanoshells were produced with a proprietary ALD process that is trademarked as PharmaShell® by Nanexa AB. The drug load was determined with HPLC-UV to 82 wt%. The test materials were administered subcutaneously in rats (1, 10, and 100 mg/kg) from which blood samples were collected during 12 weeks. Plasma was generated and analyzed with regards to indomethacin using UPLC-MS/MS. The release rate was dramatically slower for the nanoshell coated indomethacin compared with uncoated indomethacin. Drug was released in vivo during more than 12 weeks for the 10 and 100 mg/kg doses, and during 10 weeks for the 1 mg/kg dose, while uncoated indomethacin was eliminated with a half-life of 15 h, as calculated from the release data by fitting a one phase decay function. The exposure levels were similar as earlier reported for therapeutic indomethacin doses, but significantly sustained in the present study using coated drug particles in rats. In conclusion, this is the first long-term in vivo evaluation of nanoshell depot formulations. The stable plasma concentrations for more than 12 weeks demonstrate that nanoshells can enable long-term depot injections with high drug load.