Titanium is one of the most abundant elements in the earth’s crust and while there are many examples of its bioactive properties and use by living organisms, there are few studies that have probed its biochemical reactivity in physiological environments. In the cosmetic industry, TiO₂ nanoparticles are widely used. They are often incorporated in sunscreens as inorganic physical sun blockers, taking advantage of their semiconducting property, which facilitates absorbing ultraviolet (UV) radiation. Sunscreens are formulated to protect human skin from the redox activity of the TiO₂ nanoparticles (NPs) and are mass-marketed as safe for people and the environment. By closely examining the biological use of TiO₂ and the influence of biomolecules on its stability and solubility, we reassess the reactivity of the material in the presence and absence of UV energy. We also consider the alarming impact that TiO₂ NP seepage into bodies of water can cause to the environment and aquatic life, and the effect that it can have on human skin and health, in general, especially if it penetrates into the human body and the bloodstream.

One of the major drawbacks of many of the currently used cancer drugs are off-target effects. Targeted delivery is one method to minimize such unwanted and detrimental events. To actively target lung cancer cells, we have developed a conjugate of the apoptosis inducing protein cytochrome c with transferrin because the transferrin receptor is overexpressed by many rapidly dividing cancer cells. Cytochrome c and transferrin were cross-linked with a redox sensitive disulfide bond for the intra-cellular release of the protein upon endocytosis by the transferrin receptor. Confocal results demonstrated the cellular uptake of the cytochrome c-transferrin conjugate by transferrin receptor overexpressing A549 lung cancer cells. Localization studies further validated that this conjugate escaped the endosome. Additionally, an in vitro assay showed that the conjugate could induce apoptosis by activating caspase-3. The neo-conjugate not only maintained an IC₅₀ value similar to the well known drug cisplatin (50 μM) in A549 cancer cells but also was nontoxic to the normal lung (MRC5) cells. Our neo-conjugate holds promise for future development to target cancers with enhanced transferrin receptor expression.

We developed a nanoparticulate Rhizopus arrhizus lipase formulation to enhance its activity and to increase the conversion yield of lipids into fatty acid methyl esters (FAME, a.k.a., biodiesel). More than 95% purity of the lipase was achieved in a two-step purification. Nanoparticle formulation was afforded by co-lyophilization of the lipase with methyl-β-cyclodextrin (MβCD), an established lyoprotectant. Scanning electron microscopy and dynamic light scattering measurements showed a size of 75–200 nm for the nanoparticles depending on the ratio of lipase-to-MβCD employed during co-lyophilization. Fourier transform infrared spectroscopic analysis by Gaussian curve fitting of the resolution-enhanced amide I region of lyophilized and nanoparticulate lipase indicated a more native-like secondary structure in the latter. A 98% substrate-to-FAME conversion was achieved in 10 h in n-hexane by lipase nanoparticles, whereas the crude and lyophilized enzyme showed 65 and 70% conversion in 18 h, respectively. In this aspect, the lipase nanoparticles were superior to all other reported systems. Operational stability after 5 catalytic conversions of nanoparticles was found to be >81%. In summary, we herein developed a novel lipase formulation for efficient catalysis in lipid-to-biodiesel conversion.

Curcumin, a natural polyphenol derived from the spice turmeric (Curcuma longa), contains antioxidant, anti-inflammatory, and anti-cancer properties. However, curcumin bioavailability is inherently low due to poor water solubility and rapid metabolism. Here, we further refined for use curcumin incorporated into “biomimetic” nanolipoprotein particles (cNLPs) consisting of a phospholipid bilayer surrounded by apolipoprotein A1 and amphipathic polymer scaffolding moieties. Our cNLP formulation improves the water solubility of curcumin over 30-fold and produces nanoparticles with ~350 µg/mL total loading capacity for downstream in vitro and in vivo applications. We found that cNLPs were well tolerated in AG05965/MRC-5 human primary lung fibroblasts compared to cultures treated with curcumin solubilized in DMSO (curDMSO). Pre-treatment with cNLPs of quiescent G0/G1-phase MRC-5 cultures improved cell survival following ¹³⁷Cs gamma ray irradiations, although this finding was reversed in asynchronously cycling log-phase cell cultures. These findings may be useful for establishing cNLPs as a method to improve curcumin bioavailability for administration as a radioprotective and/or radiomitigative agent against ionizing radiation (IR) exposures in non-cycling cells or as a radiosensitizing agent for actively dividing cell populations, such as tumors.