Biology of TiO2-oligonucleotide nanocomposites

Orthogonal light-triggered multiple effects based on photochromic nanoparticles for DNA cleavage and beyond

Efficient and spatiotemporally controllable cleavage of deoxyribonucleic acid (DNA) is of great significance for both disease treatment (e.g. tumour, bacterial infection, etc) and molecular biology applications (e.g. gene editing). The recently developed light-induced cleavage strategy based on catalytic nanoparticles has been regarded as a promising strategy for DNA controllable cleavage. Although the regulation based on orthogonal light in biomedical applications holds more significant advantages than that based on single light, nanoparticle-mediated DNA cleavage based on orthogonal light has yet to be reported. In this article, for the first time, we demonstrated an orthogonal light-regulated nanosystem for efficient and spatiotemporal DNA cleavage. In this strategy, tungsten oxide (WO₃) nanoparticles with photochromic properties were used as nano-antennae to convert the photoenergy from the orthogonal visible light (405 nm) and near-infrared light (808 nm) into chemical energy for DNA cleavage. We verified that only the orthogonal light can trigger high cleavage efficiency on different types of DNA. Moreover, such an orthogonal light-response nano-system can not only induce significant apoptosis of tumour cells, but also effectively eliminate bacterial biofilms.

Triggering cell death in cancers using self-illuminating nanocomposites

Bioinspired photocatalysis has resulted in efficient solutions for many areas of science and technology spanning from solar cells to medicine. Here we show a new bioinspired semiconductor nanocomposite (nanoTiO₂-DOPA-luciferase, TiDoL) capable of converting light energy within cancerous tissues into chemical species that are highly disruptive to cell metabolism and lead to cell death. This localized activity of semiconductor nanocomposites is triggered by cancer-generated activators. Adenosine triphosphate (ATP) is produced in excess in cancer tissues only and activates nearby immobilized TiDoL composites, thereby eliminating its off-target toxicity. The interaction of TiDoL with cancerous cells was probed in situ and in real-time to establish a detailed mechanism of nanoparticle activation, triggering of the apoptotic signaling cascade, and finally, cancer cell death. Activation of TiDoL with non-cancerous cells did not result in cell toxicity. Exploring the activation of antibody-targeted semiconductor conjugates using ATP is a step toward a universal approach to single-cell-targeted medical therapies with more precision, efficacy, and potentially fewer side effects.

Effect of dopamine-functionalization, charge and pH on protein corona formation around TiO2 nanoparticles

Inorganic nanoparticles (NPs) are gaining increasing attention in nanomedicine because of their stimuli responsiveness, which allows combining therapy with diagnosis. However, little information is known about their interaction with intracellular or plasma proteins when they are introduced in a biological environment. Here we present atomistic molecular dynamics (MD) simulations investigating the case study of dopamine-functionalized TiO₂ nanoparticles and two proteins that are overexpressed in cancer cells, i.e. PARP1 and HSP90, since experiments proved them to be the main components of the corona in cell cultures. The mechanism and the nature of the interaction (electrostatic, van der Waals, H-bonds, etc.) is unravelled by defining the protein residues that are more frequently in contact with the NPs, the extent of contact surface area and the variations in the protein secondary structures, at different pH and ionic strength conditions of the solution where they are immersed to simulate a realistic biological environment. The effects of the NP surface functionalization and charge are also considered. Our MD results suggest that less acidic intracellular pH conditions in the presence of cytosolic ionic strength enhance PARP1 interaction with the nanoparticle, whereas the HSP90 contribution is partly weakened, providing a rational explanation to existing experimental observations.

Dopamine Adsorption on Rutile TiO2(110): Geometry, Thermodynamics, and Core-Level Shifts from First Principles

The modification of the rutile TiO₂(110) surface with dopamine represents the best example of the functionalization of TiO₂-based nanoparticles with catecholamines, which is of great interest for sunlight harvesting and drug delivery. However, there is little information on the dopamine-TiO₂(110) adsorption complex in terms of thermodynamic properties and structural parameters such as bond coordination and orientation of the terminal ethyl-amino group. Here, we report a density functional theory (DFT) investigation of dopamine adsorption on the TiO₂(110) surface using the optB86b-vdW functional with a Hubbard-type correction to the Ti 3d orbitals, where U _eff = 3 eV. Guided by available X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) data, our simulations identify enolate species with bidentate coordination at a submonolayer coverage, which are bonded to two neighboring 5-fold-coordinated Ti atoms at the TiO₂(110) surface through both deprotonated oxygen atoms of the dopamine, i.e., in a bridging fashion. The process is highly exothermic, involving an adsorption energy of -2.90 eV. Calculated structural parameters suggest that the molecule sits approximately upright on the surface with the amino group interacting with the π-like orbitals of the aromatic ring, leading to a gauche-like configuration. The resulting NH···π hydrogen bond in this configuration can be broken by overcoming an energy barrier of 0.22 eV; in this way, the amino group rotation leads to an anti-like conformation, making this terminal group able to bind to other biomolecules. This mechanism is endothermic by 0.07 eV. Comparison of existing spectroscopic data with DFT modeling shows that our computational setup can reproduce most experimentally determined parameters such as tilt angles from NEXAFS and chemical shifts in XPS, which allows us to identify the preferred mode of adsorption of dopamine on the TiO₂(110) surface.

Room temperature bilayer water structures on a rutile TiO2(110) surface: hydrophobic or hydrophilic?

The lack of understanding of the molecular-scale water adsorbed on TiO₂ surfaces under ambient conditions has become a major obstacle for solving the long-time scientific and applications issues, such as the photo-induced wetting phenomenon and designing novel advanced TiO₂-based materials. Here, with the molecular dynamics simulation, we identified an ordered water bilayer structure with a two-dimensional hydrogen bonding network on a rutile TiO₂(110) surface at ambient temperature, corroborated by vibrational sum-frequency generation spectroscopy. The reduced number of hydrogen bonds between the water bilayer and water droplet results in a notable water contact angle (25 ± 5°) of the pristine TiO₂ surface. This surface hydrophobicity can be enhanced by the adsorption of the formate/acetate molecules, and diminishes with dissociated H₂O molecules. Our new physical framework well explained the long-time controversy on the origin of the hydrophobicity/hydrophilicity of the TiO₂ surface, thus help understanding the efficiency of TiO₂ devices in producing electrical energy of solar cells and the photo-oxidation of organic pollutants.

An ordered water bilayer structure was identified on a rutile TiO₂(110) surface at ambient temperature by combining VSFG experiments and MD simulations, which well explained the long-time controversy on the wetting behaviors of the TiO₂ surface.

Phototherapy and optical waveguides for the treatment of infection

With rapid emergence of multi-drug resistant microbes, it is imperative to seek alternative means for infection control. Optical waveguides are an auspicious delivery method for precise administration of phototherapy. Studies have shown that phototherapy is promising in fighting against a myriad of infectious pathogens (i.e. viruses, bacteria, fungi, and protozoa) including biofilm-forming species and drug-resistant strains while evading treatment resistance. When administered via optical waveguides, phototherapy can treat both superficial and deep-tissue infections while minimizing off-site effects that afflict conventional phototherapy and pharmacotherapy. Despite great therapeutic potential, exact mechanisms, materials, and fabrication designs to optimize this promising treatment option are underexplored. This review outlines principles and applications of phototherapy and optical waveguides for infection control. Research advances, challenges, and outlook regarding this delivery system are rigorously discussed in a hope to inspire future developments of optical waveguide-mediated phototherapy for the management of infection and beyond.

Use of X-Ray Fluorescence Microscopy for Studies on Research Models of Hepatocellular Carcinoma

Introduction: TheraSphere^® microspheres containing yttrium ⁹⁰Y are among many radioembolization agents used clinically to reduce liver tumor burden, and their effects on cancer volume reduction are well-established. At the same time, concerns about off target tissue injury often limit their use. Deeper investigation into tissue distribution and long-term impact of these microspheres could inform us about additional ways to use them in practice.

Methods: Healthy rat liver and rabbit liver tumor samples from animals treated with TheraSpheres were sectioned and their elemental maps were generated by X-ray fluorescence microscopy (XFM) at the Advanced Photon Source (APS) synchrotron at Argonne National Laboratory (ANL).

Results: Elemental imaging allowed us to identify the presence and distribution of TheraSpheres in animal tissues without the need for additional sample manipulation or staining. Ionizing radiation produced by ⁹⁰Y radioactive contaminants present in these microspheres makes processing TheraSphere treated samples complex. Accumulation of microspheres in macrophages was observed.

Conclusions: This is the first study that used XFM to evaluate the location of microspheres and radionuclides in animal liver and tumor samples introduced through radioembolization. XFM has shown promise in expanding our understanding of radioembolization and could be used for investigation of human patient samples in the future.

Development of Multi-Scale X-ray Fluorescence Tomography for Examination of Nanocomposite-Treated Biological Samples

Simple Summary

Metal-oxide nanomaterials enter cancer and normal cells even when not specifically targeted, and often interact with specific cellular structures and biological molecules solely due to their innate physical-chemical properties. This raises concerns for the use of nanoparticles, which can be alleviated only with rigorous studies of nanoparticle–cell interactions, studies independent of post-interaction labeling of nanomaterials. X-ray fluorescence microscopy is an imaging technique that quantifies and maps all chemical elements from the periodic table solely based on their native fluorescence excited by the incoming X-ray. We used two different instruments to interrogate the same sample in 3D at two different resolutions and determine heterogeneity of cell-to-cell interactions with nanomaterials, as well as subcellular nanoparticle distribution. This is the first example of multi-scale 3D X-ray fluorescence imaging. This work begins a new era of study on how nanoparticle-based therapies can be developed to be more predictable and safer for use.

Abstract

Research in cancer nanotechnology is entering its third decade, and the need to study interactions between nanomaterials and cells remains urgent. Heterogeneity of nanoparticle uptake by different cells and subcellular compartments represent the greatest obstacles to a full understanding of the entire spectrum of nanomaterials’ effects. In this work, we used flow cytometry to evaluate changes in cell cycle associated with non-targeted nanocomposite uptake by individual cells and cell populations. Analogous single cell and cell population changes in nanocomposite uptake were explored by X-ray fluorescence microscopy (XFM). Very few nanoparticles are visible by optical imaging without labeling, but labeling increases nanoparticle complexity and the risk of modified cellular uptake. XFM can be used to evaluate heterogeneity of nanocomposite uptake by directly imaging the metal atoms present in the metal-oxide nanocomposites under investigation. While XFM mapping has been performed iteratively in 2D with the same sample at different resolutions, this study is the first example of serial tomographic imaging at two different resolutions. A cluster of cells exposed to non-targeted nanocomposites was imaged with a micron-sized beam in 3D. Next, the sample was sectioned for immunohistochemistry as well as a high resolution “zoomed in” X-ray fluorescence (XRF) tomography with 80 nm beam spot size. Multiscale XRF tomography will revolutionize our ability to explore cell-to-cell differences in nanomaterial uptake.

d-Glucose Adsorption on the TiO2 Anatase (100) Surface: A Direct Comparison Between Cluster-Based and Periodic Approaches

Titanium dioxide (TiO2) has been extensively studied as a suitable material for a wide range of fields including catalysis and sensing. For example, TiO2-based nanoparticles are active in the catalytic conversion of glucose into value-added chemicals, while the good biocompatibility of titania allows for its application in innovative biosensing devices for glucose detection. A key process for efficient and selective biosensors and catalysts is the interaction and binding mode between the analyte and the sensor/catalyst surface. The relevant features regard both the molecular recognition event and its effects on the nanoparticle electronic structure. In this work, we address both these features by combining two first-principles methods based on periodic boundary conditions and cluster approaches (CAs). While the former allows for the investigation of extended materials and surfaces, CAs focus only on a local region of the surface but allow for using hybrid functionals with low computational cost, leading to a highly accurate description of electronic properties. Moreover, the CA is suitable for the study of reaction mechanisms and charged systems, which can be cumbersome with PBC. Here, a direct and detailed comparison of the two computational methodologies is applied for the investigation of d-glucose on the TiO2 (100) anatase surface. As an alternative to the commonly used PBC calculations, the CA is successfully exploited to characterize the formation of surface and subsurface oxygen vacancies and to determine their decisive role in d-glucose adsorption. The results of such direct comparison allow for the selection of an efficient, finite-size structural model that is suitable for future investigations of biosensor electrocatalytic processes and biomass conversion catalysis.

Development of Fe3O4 core–TiO2 shell nanocomposites and nanoconjugates as a foundation for neuroblastoma radiosensitization

Background

Neuroblastoma is the most common extracranial solid malignancy in childhood which, despite the current progress in radiotherapy and chemotherapy protocols, still has a high mortality rate in high risk tumors. Nanomedicine offers exciting and unexploited opportunities to overcome the shortcomings of conventional medicine. The photocatalytic properties of Fe3O4 core-TiO2 shell nanocomposites and their potential for cell specific targeting suggest that nanoconstructs produced using Fe3O4 core-TiO2 shell nanocomposites could be used to enhance radiation effects in neuroblastoma. In this study, we evaluated bare, metaiodobenzylguanidine (MIBG) and 3,4-Dihydroxyphenylacetic acid (DOPAC) coated Fe3O4@TiO2 as potential radiosensitizers for neuroblastoma in vitro.

Results

The uptake of bare and MIBG coated nanocomposites modestly sensitized neuroblastoma cells to ionizing radiation. Conversely, cells exposed to DOPAC coated nanocomposites exhibited a five-fold enhanced sensitivity to radiation, increased numbers of radiation induced DNA double-strand breaks, and apoptotic cell death. The addition of a peptide mimic of the epidermal growth factor (EGF) to nanoconjugates coated with MIBG altered their intracellular distribution. Cryo X-ray fluorescence microscopy tomography of frozen hydrated cells treated with these nanoconjugates revealed cytoplasmic as well as nuclear distribution of the nanoconstructs.

Conclusions

The intracellular distribution pattern of different nanoconjugates used in this study was different for different nanoconjugate surface molecules. Cells exposed to DOPAC covered nanoconjugates showed the smallest nanoconjugate uptake, with the most prominent pattern of large intracellular aggregates. Interestingly, cells treated with this nanoconjugate also showed the most pronounced radiosensitization effect in combination with the external beam x-ray irradiation. Further studies are necessary to evaluate mechanistic basis for this increased radiosensitization effect. Preliminary studies with the nanoparticles carrying an EGF mimicking peptide showed that this approach to targeting could perhaps be combined with a different approach to radiosensitization – use of nanoconjugates in combination with the radioactive iodine. Much additional work will be necessary in order to evaluate possible benefits of targeted nanoconjugates carrying radionuclides.

Graphic abstract

X-ray Fluorescence Uptake Measurement of Functionalized Gold Nanoparticles in Tumor Cell Microsamples

Quantitative cellular in vitro nanoparticle uptake measurements are possible with a large number of different techniques, however, all have their respective restrictions. Here, we demonstrate the application of synchrotron-based X-ray fluorescence imaging (XFI) on prostate tumor cells, which have internalized differently functionalized gold nanoparticles. Total nanoparticle uptake on the order of a few hundred picograms could be conveniently observed with microsamples consisting of only a few hundreds of cells. A comparison with mass spectroscopy quantification is provided, experimental results are both supported and sensitivity limits of this XFI approach extrapolated by Monte-Carlo simulations, yielding a minimum detectable nanoparticle mass of just 5 pg. This study demonstrates the high sensitivity level of XFI, allowing non-destructive uptake measurements with very small microsamples within just seconds of irradiation time.

Plant synthetic biology for producing potent phyto-antimicrobials to combat antimicrobial resistance

Inappropriate and injudicious use of antimicrobial drugs in human health, hygiene, agriculture, animal husbandry and food industries has contributed significantly to rapid emergence and persistence of antimicrobial resistance (AMR), one of the serious global public health threats. The crisis of AMR versus slower discovery of newer antibiotics put forth a daunting task to control these drug-resistant superbugs. Several phyto-antimicrobials have been identified in recent years with direct-killing (bactericidal) and/or drug-resistance reversal (re-sensitization of AMR phenotypes) potencies. Phyto-antimicrobials may hold the key in combating AMR owing to their abilities to target major microbial drug-resistance determinants including cell membrane, drug-efflux pumps, cell communication and biofilms. However, limited distribution, low intracellular concentrations, eco-geographical variations, beside other considerations like dynamic environments, climate change and over-exploitation of plant-resources are major blockades in full potential exploration phyto-antimicrobials. Synthetic biology (SynBio) strategies integrating metabolic engineering, RNA-interference, genome editing/engineering and/or systems biology approaches using plant chassis (as engineerable platforms) offer prospective tools for production of phyto-antimicrobials. With expanding SynBio toolkit, successful attempts towards introduction of entire gene cluster, reconstituting the metabolic pathway or transferring an entire metabolic (or synthetic) pathway into heterologous plant systems highlight the potential of this field. Through this perspective review, we are presenting herein the current situation and options for addressing AMR, emphasizing on the significance of phyto-antimicrobials in this apparently post-antibiotic era, and effective use of plant chassis for phyto-antimicrobial production at industrial scales along with major SynBio tools and useful databases. Current knowledge, recent success stories, associated challenges and prospects of translational success are also discussed.

Toxicological effects of Ag2O and Ag2CO3 doped TiO2 nanoparticles and pure TiO2 particles on zebrafish (Danio rerio)

In this study, the toxic effects of silver oxide and silver carbonate doped TiO₂ nanoparticles (Ag₂O-TiO₂ NPs and Ag₂CO₃-TiO₂NPs), TiO₂ nanoparticles (TiO₂ NPs), and bulk TiO₂ on gene expression, lipid peroxidation, genotoxicity, and histological alterations in zebrafish (Danio rerio) was assessed. The physicochemical properties of the synthesized nanoparticles were evaluated by X-ray diffraction (XRD), Scanning Electron Microscope (SEM), diffuse reflectance spectroscopy (DRS), dynamic light scattering (DLS), and Zeta potential analyses. TiO₂NPs after doping with Ag showed shift to higher wavelengths and decrease of band gap energy. Also, remarkable reduction in the size of Ag-doped TiO₂NPs in comparison with the TiO₂ NPs was observed. According to our results, acute toxicity increased in the order of bulk TiO₂ < TiO₂ NPs < Ag₂O-TiO₂NPs < Ag₂CO₃-TiO₂NPs, respectively. Results of sub-lethal experiments after 30 days of exposure, showed higher expression of Gpx, Hsp70, Ucp-2, and Bax genes, and lower expression of Bcl-2 gene in Ag-doped TiO₂NPs than pure TiO₂ particles (TiO₂ NPs and bulk TiO₂) treatments (p < 0.05). However, the mRNA levels of SOD and CAT genes were significantly higher in pure TiO₂ particles than doped TiO₂NPs (p < 0.05). Moreover, levels of malondialdehyde, abnormalities of peripheral blood cells and severity of histological lesions in liver, gill, intestine and kidney tissues were more evident in Ag-dopedTiO₂ NPs than pure TiO₂ particles. It can be concluded that Ag doping of TiO₂ NPs significantly increased their toxicity and resulted in more histological lesions, apoptosis and oxidative stress than pure TiO₂ particles in adult zebrafish.

Dopamine-Decorated TiO2 Nanoparticles in Water: A QM/MM vs an MM Description

Nanoparticle functionalization is a modern strategy in nanotechnology to build up devices for several applications. Modeling fully decorated metal oxide nanoparticles of realistic size (few nanometers) in an aqueous environment is a challenging task. In this work, we present a case study relevant for solar-light exploitation and for biomedical applications, i.e., a dopamine-functionalized TiO₂ nanoparticle (1700 atoms) in bulk water, for which we have performed an extensive comparative investigation with both MM and QM/MM approaches of the structural properties and of the conformational dynamics. We have used a combined multiscale protocol for a more efficient exploration of the complex conformational space. On the basis of the results of this study and of some QM and experimental data, we have defined strengths and limitations of the existing force field parameters. Our findings will be useful for an improved modeling and simulation of many other similar hybrid bioinorganic nanosystems in an aqueous environment that are pivotal in a broad range of nanotechnological applications.

Comprehensive Survey on Nanobiomaterials for Bone Tissue Engineering Applications

One of the most important ideas ever produced by the application of materials science to the medical field is the notion of biomaterials. The nanostructured biomaterials play a crucial role in the development of new treatment strategies including not only the replacement of tissues and organs, but also repair and regeneration. They are designed to interact with damaged or injured tissues to induce regeneration, or as a forest for the production of laboratory tissues, so they must be micro-environmentally sensitive. The existing materials have many limitations, including impaired cell attachment, proliferation, and toxicity. Nanotechnology may open new avenues to bone tissue engineering by forming new assemblies similar in size and shape to the existing hierarchical bone structure. Organic and inorganic nanobiomaterials are increasingly used for bone tissue engineering applications because they may allow to overcome some of the current restrictions entailed by bone regeneration methods. This review covers the applications of different organic and inorganic nanobiomaterials in the field of hard tissue engineering.

Protein Binding Effects of Dopamine Coated Titanium Dioxide Shell Nanoparticles

Non-targeted nanoparticles are capable of entering cells, passing through different subcellular compartments and accumulating on their surface a protein corona that changes over time. In this study, we used metal oxide nanoparticles with iron-oxide core covered with titanium dioxide shell (Fe3O4@TiO2), with a single layer of covalently bound dopamine covering the nanoparticle surface. Mixing nanoparticles with cellular protein isolates showed that these nanoparticles can form complexes with numerous cellular proteins. The addition of non-toxic quantities of nano-particles to HeLa cell culture resulted in their non-specific uptake and accumulation of protein corona on nanoparticle surface. TfRC, Hsp90 and PARP were followed as representative protein components of nanoparticle corona; each protein bound to nanoparticles with different affinity. The presence of nanoparticles in cells also mildly modulated gene expression on the level of mRNA. In conclusion, cells exposed to non-targeted nanoparticles show subtle but numerous changes that are consistent from one experiment to another.

Proton Transfers at a Dopamine-Functionalized TiO2 Interface

Despite the many successful syntheses and applications of dopamine-functionalized TiO₂ nanohybrids, there has not yet been an atomistic understanding of the interaction of this 1,2-dihydroxybenzene derivative ligand with the titanium dioxide surfaces. In this work, on the basis of a wide set of dispersion-corrected hybrid density functional theory (DFT) calculations and density functional tight binding (DFTB) molecular dynamics simulations, we present a detailed study of the adsorption modes, patterns of growth, and configurations of dopamine on the anatase (101) TiO₂ surface, with reference to the archetype of 1,2-dihydroxybenzene ligands, i.e., catechol. At low coverage, the isolated dopamine molecule prefers to bend toward the surface, coordinating the NH₂ group to a Ti_5c ion. At high coverage, the packed molecules succeed in bending toward the surface only in some monolayer configurations. When they do, we observe a proton transfer from the surface to the ethyl-amino group, forming terminal NH₃ ⁺ species, which highly interact with the O atoms of a neighboring dopamine molecule. This strong Coulombic interaction largely stabilizes the self-assembled monolayer. On the basis of these results, we predict that improving the probability of dopamine molecules being free to bend toward the surface through thermodynamic versus kinetic growth conditions will lead to a monolayer of fully protonated dopamine molecules.

Exogenous Physical Irradiation on Titania Semiconductors: Materials Chemistry and Tumor-Specific Nanomedicine

Titania semiconductors can be activated by external physical triggers to produce electrons (e-) and holes (h+) pairs from the energy-band structure and subsequently induce the generation of reactive oxygen species for killing cancer cells, but the traditional ultraviolet light with potential phototoxicity and low-tissue-penetrating depth as the irradiation source significantly hinders the further in vivo broad biomedical applications. Here, the very-recent development of novel exogenous physical irradiation of titania semiconductors for tumor-specific therapies based on their unique physiochemical properties, including near infrared (NIR)-triggered photothermal hyperthermia and photodynamic therapy, X-ray/Cerenkov radiation-activated deep-seated photodynamic therapy, ultrasound-triggered sonodynamic therapy, and the intriguing synergistic therapeutic paradigms by combined exogenous physical irradiations are in focus. Most of these promising therapeutic modalities are based on the semiconductor nature of titania nanoplatforms, together with their defect modulation for photothermal hyperthermia. The biocompatibility and biosafety of these titania semiconductors are also highlighted for guaranteeing their further clinical translation. Challenges and future developments of titania-based therapeutic nanoplatforms and the corresponding developed therapeutic modalities for potential clinical translation of tumor-specific therapy are also discussed and outlooked.

High-spatial-resolution x-ray fluorescence tomography with spectrally matched nanoparticles

Present macroscopic biomedical imaging methods provide either morphology with high spatial resolution (e.g. CT) or functional/molecular information with lower resolution (e.g. PET). X-ray fluorescence (XRF) from targeted nanoparticles allows molecular or functional imaging but sensitivity has so far been insufficient resulting in low spatial resolution, despite long exposure times and high dose. In the present paper, we show that laboratory XRF tomography with metal-core nanoparticles (NPs) provides a path to functional/molecular biomedical imaging with ~100 µm resolution in living rodents. The high sensitivity and resolution rely on the combination of a high-brightness liquid-metal-jet x-ray source, pencil-beam optics, photon-counting energy-dispersive detection, and spectrally matched NPs. The method is demonstrated on mice for 3D tumor imaging via passive targeting of in-house-fabricated molybdenum NPs. Exposure times, nanoparticle dose, and radiation dose agree well with in vivo imaging.

Antisense oligonucleotides for the arterial hypertension mechanisms study and therapy

Arterial hypertension is one of the most common chronic diseases in adults all over the world. This pathology can not only reduce patients’ life quality, but can also be accompanied by a number of complications. Despite the fact that there is a large group of antihypertensive drugs on the market, mainly representing different combinations of inhibitors of the renin-angiotensin system, adrenoreceptor blockers in combination with diuretics, there is no generally accepted “gold standard” for drugs that would not have side effects. The review discusses the main aspects of antisense oligonucleotides use in the context of arterial hypertension. It is well known that the medical implementation of antisense oligonucleotides aims to block the expression of particular genes involved in the pathology development, and a key advantage of this technique is a high selectivity of the effect. However, with the undoubted advantages of the method, there are difficulties in its application, related both to the properties of the oligonucleotides themselves (insufficient stability and poor penetration into cells), and to the variety of mechanisms of the origin of a particular pathology, arterial hypertension, in our case. The review provides a brief description of the main molecular targets for antisense treatment of hypertensive disease. The newest targets for therapy with oligonucleotides – microRNAs – are discussed. The main modifications of antisense nucleotides, designed to increase the duration of their effects and simplify the delivery of this type of drugs to the targets are discussed, in particular, combining antisense oligonucleotides with adenovirus-based expression vectors. Particular attention is given to antisense oligonucleotides in the complex with nanoparticles. The review discusses the results of the use of titanium dioxide (TiO2) containing antisense nanocomposites for the angiotensin converting enzyme in rats with stress induced arterial hypertension (ISIAH). It was shown that the use of antisense oligonucleotides continues to be a promising technique for studying the mechanisms of various forms of hypertensive disease and has a high potential for therapeutic use.

Towards the Identification of an In Vitro Tool for Assessing the Biological Behavior of Aerosol Supplied Nanomaterials

Nanoparticles (NP)-based inhalation systems for drug delivery can be administered in liquid form, by nebulization or using pressurized metered dose inhalers, and in solid form by means of dry powder inhalers. However, NP delivery to the lungs has many challenges including the formulation instability due to particle-particle interactions and subsequent aggregation, causing poor deposition in the small distal airways and subsequent alveolar macrophages activity, which could lead to inflammation. This work aims at providing an in vitro experimental design for investigating the correlation between the physico-chemical properties of NP, and their biological behavior, when they are used as NP-based inhalation treatments, comparing two different exposure systems. By means of an aerosol drug delivery nebulizer, human lung cells cultured at air–liquid interface (ALI) were exposed to two titanium dioxide NP (NM-100 and NM-101), obtained from the JRC repository. In parallel, ALI cultures were exposed to NP suspension by direct inoculation, i.e., by adding the NP suspensions on the apical side of the cell cultures with a pipette. The formulation stability of NP, measured as hydrodynamic size distributions, the cell viability, cell monolayer integrity, cell morphology and pro-inflammatory cytokines secretion were investigated. Our results demonstrated that the formulation stability of NM-100 and NM-101 was strongly dependent on the aggregation phenomena that occur in the conditions adopted for the biological experiments. Interestingly, comparable biological data between the two exposure methods used were observed, suggesting that the conventional exposure coupled to ALI culturing conditions offers a relevant in vitro tool for assessing the correlation between the physico-chemical properties of NP and their biological behavior, when NP are used as drug delivery systems.

Effect of heating on the structural and optical properties of TiO2 nanoparticles: antibacterial activity

TiO2 nanoparticles were synthesized at room temperature by chemical precipitation method and were then heated at 120, 300, 600 and 900 °C temperatures. The phase transition and crystallite size variation were determined by X-rays diffraction (XRD) analysis. The surface area, pore volume and pore size were measured using Brunauer–Emmet–Teller (BET) and Barrett–Joyner–Halenda (BJH) methods. The optical activity of heat treated and non-heat treated samples were carried out by diffuse reflectance (DR) spectroscopy. Four different methods were used to calculate band gap energy. The results obtained from thermogravimetric and differential thermal gravimetric (TG/TDG) analyses and Fourier transform infra-red (FTIR) spectroscopy agreed with each other. Agar well diffusion method has been applied to explore the antibacterial activity of nanoparticles against different bacterial strains such as Bacillus subtilis, Staphylococcus Aureus, Escherichia coli and Pseudomonas Aeruginosa. It was observed that TiO2 nanoparticles heated at 120 °C displayed maximum antibacterial activity while those heated at higher temperature showed no activity against the examined bacteria.

Intracellular in situ labeling of TiO2 nanoparticles for fluorescence microscopy detection

Titanium dioxide (TiO₂) nanoparticles are produced for many different purposes, including development of therapeutic and diagnostic nanoparticles for cancer detection and treatment, drug delivery, induction of DNA double-strand breaks, and imaging of specific cells and subcellular structures. Currently, the use of optical microscopy, an imaging technique most accessible to biology and medical pathology, to detect TiO₂ nanoparticles in cells and tissues ex vivo is limited with low detection limits, while more sensitive imaging methods (transmission electron microscopy, X-ray fluorescence microscopy, etc.) have low throughput and technical and operational complications. Herein, we describe two in situ post-treatment labeling approaches to stain TiO₂ nanoparticles taken up by the cells. The first approach utilizes fluorescent biotin and fluorescent streptavidin to label the nanoparticles before and after cellular uptake; the second approach is based on the copper-catalyzed azide-alkyne cycloaddition, the so-called Click chemistry, for labeling and detection of azide-conjugated TiO₂ nanoparticles with alkyne-conjugated fluorescent dyes such as Alexa Fluor 488. To confirm that optical fluorescence signals of these nanoparticles match the distribution of the Ti element, we used synchrotron X-ray fluorescence microscopy (XFM) at the Advanced Photon Source at Argonne National Laboratory. Titanium-specific XFM showed excellent overlap with the location of optical fluorescence detected by confocal microscopy. Therefore, future experiments with TiO₂ nanoparticles may safely rely on confocal microscopy after in situ nanoparticle labeling using approaches described here.

Ag-doping regulates the cytotoxicity of TiO2 nanoparticles via oxidative stress in human cancer cells

We investigated the anticancer potential of Ag-doped (0.5-5%) anatase TiO2 NPs. Characterization study showed that dopant Ag was well-distributed on the surface of host TiO2 NPs. Size (15 nm to 9 nm) and band gap energy (3.32 eV to 3.15 eV) of TiO2 NPs were decreases with increasing the concentration of Ag dopant. Biological studies demonstrated that Ag-doped TiO2 NP-induced cytotoxicity and apoptosis in human liver cancer (HepG2) cells. The toxic intensity of TiO2 NPs was increases with increasing the amount of Ag-doping. The Ag-doped TiO2 NPs further found to provoke reactive oxygen species (ROS) generation and antioxidants depletion. Toxicity induced by Ag-doped TiO2 NPs in HepG2 cells was efficiently abrogated by antioxidant N-acetyl-cysteine (ROS scavenger). We also found that Ag-doped TiO2 NPs induced cytotoxicity and oxidative stress in human lung (A549) and breast (MCF-7) cancer cells. Interestingly, Ag-doped TiO2 NPs did not cause much toxicity to normal cells such as primary rat hepatocytes and human lung fibroblasts. Overall, we found that Ag-doped TiO2 NPs have potential to selectively kill cancer cells while sparing normal cells. This study warranted further research on anticancer potential of Ag-doped TiO2 NPs in various types of cancer cells and in vivo models.

AgNPs-decorated 3D printed PEEK implant for infection control and bone repair

Polyetheretherketone (PEEK) is an ideal substitute material for bone tissue engineering, which can avoid the stress shielding phenomenon due to its similar mechanical properties to natural human bone. Complex bone defect and postoperative infection are still two enormous challenges in orthopedic clinics. It's well-known that additive manufacturing possesses the merits of high-precision and rapid prototyping, thus it easily meets the needs of mold processing. In the present study, we developed a novel Ag-decorated 3D printed PEEK via catecholamine chemistry. SEM image showed that silver nanoparticles (AgNPs) were evenly anchored on the surface. The following antibacterial tests, including bacterial inhibition ring, bacterial dynamics curves and antibiofilm test, indicated that the Ag-decorated 3D PEEK scaffolds displayed significant antibacterial effect towards Gram-negative and Gram-positive bacteria. Then MG-63 cells were seeded on samples for cell proliferation and ALP activity tests. The results demonstrated the scaffold modified with AgNPs could support cell proliferation, and enhanced higher alkaline phosphatase activity compared with pure PEEK scaffold. Expectedly, this dual functional 3D material holds great potential application in clinical bone tissue repair.

Black TiO2 based core-shell nanocomposites as doxorubicin carriers for thermal imaging guided synergistic therapy of breast cancer

TiO₂ nanomaterials have been widely used for anticancer drug carriers and UV/980 nm NIR triggered cancer synergistic platforms. However, traditional pure TiO₂ nanocarriers encounter some serious drawbacks, such as low drug loading ability, limited tissue penetration of UV light, and heating effect of 980 nm NIR on normal tissue, which obstruct their further application in cancer treatment. To overcome those challenges, novel mesoporous silica (mSiO₂) coated black TiO₂ core-shell nanocomposites are designed and constructed as doxorubicin carriers for 808 nm NIR triggered thermal imaging guided photothermal therapy combined chemotherapy of breast cancer. Properties of the nanocomposites such as micro-morphology, size, drug loading ability and release, targeting performance, and therapy efficiency in vitro and in vivo were evaluated. The results indicated the core-shell nanocomposites with dramatically increased loading ability were pH-responsive/NIR-accelerated doxorubicin release nanocarriers and showed synergistic breast cancer treatment in vitro and in vivo. This study verifies that the newly prepared mSiO₂ coated black TiO₂ core-shell nanocarriers can overcome the limitations of traditional TiO₂ nanocarriers and thus improve and broaden usage of TiO₂ nanoparticles in nanomedicine.

Synchrotron-based X-ray microscopy for sub-100nm resolution cell imaging

Microscopic imaging provides a straightforward approach to deepen our understanding of cellular events. While the resolution of optical microscopes is generally limited to 200-300nm due to the diffraction limit, there has been ever growing interest in studying cells at the sub-100nm regime. By exploiting the short wavelength, long penetration depth and elemental specificity of X-rays, synchrotron-based X-ray microscopy (XRM) has demonstrated its power in exploring the structure and function of cells at the nanometer resolution. Here we summarize recent advances in using XRM for imaging ultrastructure of organelles and specific biomolecular locations in cells, and provide a perspective on potentials and applications of XRM.

Characterization of the Interactions between Titanium Dioxide Nanoparticles and Polymethoxyflavones Using Surface-Enhanced Raman Spectroscopy

Nanosized titanium dioxide (TiO₂) particles are commonly present in TiO₂ food additives (E171) and have been associated with potential adverse effects on health. However, little knowledge is available regarding the interactions between TiO₂ nanoparticles (NPs) and other food components, such as flavonoids. In this study, we aim to study the molecular interactions between TiO₂ anatase NPs and three structurally closely related polymethoxyflavones (PMFs, flavonoids found in citrus fruits), namely, 3',4'-didemethylnobiletin (DDN), 5-demethylnobiletin (5DN), and 5,3',4'-tridemethylnobiletin (TDN), using ultraviolet-visible (UV-vis) spectrometry and surface-enhanced Raman spectroscopy (SERS). In the UV-vis absorption spectra, bathochromic effects were observed after DDN and TDN conjugated with TiO₂ NPs. The results from SERS analysis clearly demonstrated that DDN and TDN could bind TiO₂ NPs with the functional groups 3'-OH and 4'-OH on ring B and formed charge-transfer complexes. However, 5DN with functional groups C═O on ring C and 5-OH on ring A could not bind TiO₂ NPs. Knowledge on the molecular interactions between TiO₂ NPs and food components, such as flavonoids, will facilitate the understanding of the fate of TiO₂ NPs during food processing and in the gastrointestinal tract after oral consumption.

Preserving elemental content in adherent mammalian cells for analysis by synchrotron-based x-ray fluorescence microscopy

Trace metals play important roles in biological function, and x-ray fluorescence microscopy (XFM) provides a way to quantitatively image their distribution within cells. The faithfulness of these measurements is dependent on proper sample preparation. Using mouse embryonic fibroblast NIH/3T3 cells as an example, we compare various approaches to the preparation of adherent mammalian cells for XFM imaging under ambient temperature. Direct side-by-side comparison shows that plunge-freezing-based cryoimmobilization provides more faithful preservation than conventional chemical fixation for most biologically important elements including P, S, Cl, K, Fe, Cu, Zn and possibly Ca in adherent mammalian cells. Although cells rinsed with fresh media had a great deal of extracellular background signal for Cl and Ca, this approach maintained cells at the best possible physiological status before rapid freezing and it does not interfere with XFM analysis of other elements. If chemical fixation has to be chosen, the combination of 3% paraformaldehyde and 1.5 % glutaraldehyde preserves S, Fe, Cu and Zn better than either fixative alone. When chemically fixed cells were subjected to a variety of dehydration processes, air drying was proved to be more suitable than other drying methods such as graded ethanol dehydration and freeze drying. This first detailed comparison for x-ray fluorescence microscopy shows how detailed quantitative conclusions can be affected by the choice of cell preparation method.

Distribution of Iron Oxide Core-Titanium Dioxide Shell Nanoparticles in VX2 Tumor Bearing Rabbits Introduced by Two Different Delivery Modalities

This work compares intravenous (IV) versus fluoroscopy-guided transarterial intra-catheter (IC) delivery of iron oxide core-titanium dioxide shell nanoparticles (NPs) in vivo in VX2 model of liver cancer in rabbits. NPs coated with glucose and decorated with a peptide sequence from cortactin were administered to animals with developed VX2 liver cancer. Two hours after NPs delivery tumors, normal liver, kidney, lung and spleen tissues were harvested and used for a series on histological and elemental analysis tests. Quantification of NPs in tissues was done both by bulk inductively coupled plasma mass spectrometry (ICP-MS) analysis and by hard X-ray fluorescence microscopy. Both IV and IC NPs injection are feasible modalities for delivering NPs to VX2 liver tumors with comparable tumor accumulation. It is possible that this is an outcome of the fact that VX2 tumors are highly vascularized and hemorrhagic, and therefore enhanced permeability and retention (EPR) plays the most significant role in accumulation of nanoparticles in tumor tissue. It is, however, interesting to note that IV delivery led to increased sequestration of NPs by spleen and normal liver tissue, while IC delivery lead to more NP positive Kupffer cells. This difference is most likely a direct outcome of blood flow dynamics. Armed with this knowledge about nanoparticle delivery, we plan to test them as radiosensitizers in the future.

Layered bismuth oxyhalide nanomaterials for highly efficient tumor photodynamic therapy

Layered bismuth oxyhalide nanomaterials have received much more interest as promising photocatalysts because of their unique layered structures and high photocatalytic performance, which can be used as potential inorganic photosensitizers in tumor photodynamic therapy (PDT). In recent years, photocatalytic materials have been widely used in PDT and photothermal therapy (PTT) as inorganic photosensitizers. This investigation focuses on applying layered bismuth oxyhalide nanomaterials toward cancer PDT, an application that has never been reported so far. The results of our study indicate that the efficiency of UV-triggered PDT was highest when using BiOCl nanoplates followed by BiOCl nanosheets, and then TiO2. Of particular interest is the fact that layered BiOCl nanomaterials showed excellent PDT effects under low nanomaterial dose (20 μg mL(-1)) and low UV dose (2.2 mW cm(-2) for 10 min) conditions, while TiO2 showed almost no therapeutic effect under the same parameters. BiOCl nanoplates and nanosheets have shown excellent performance and an extensive range of applications in PDT.

Bio-effect of nanoparticles in the cardiovascular system

Nanoparticles (NPs; < 100 nm) are increasingly being applied in various fields due to their unique physicochemical properties. The increase in human exposure to NPs has raised concerns regarding their health and safety profiles. The potential correlation between NP exposure and several cardiovascular (CV) events has been demonstrated. The aim of this review is to provide a comprehensive evaluation of the current knowledge regarding the bio-toxic impacts of titanium oxide, silver, silica, carbon black, carbon nanotube, and zinc oxide NPs exposure on the CV system in terms of in vivo and in vitro experiments, which is not fully understood presently. Moreover, the potential toxic mechanisms of NPs in the CV system that are still being questioned are elaborately discussed, and the underlying capacity of NPs used in medicine for CV events are summarized. It will be an important instrument to extrapolate relevant data for human CV risk evaluation and management. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2881-2897, 2016.

ROS-generating TiO2 nanoparticles for non-invasive sonodynamic therapy of cancer

The non-invasive photodynamic therapy has been limited to treat superficial tumours, primarily ascribed to poor tissue penetration of light as the energy source. Herein, we designed a long-circulating hydrophilized titanium dioxide nanoparticle (HTiO2 NP) that can be activated by ultrasound to generate reactive oxygen species (ROS). When administered systemically to mice, HTiO2 NPs effectively suppressed the growth of superficial tumours after ultrasound treatments. In tumour tissue, the levels of proinflammatory cytokines were elevated several fold and intense vascular damage was observed. Notably, ultrasound treatments with HTiO2 NPs also suppressed the growth of deeply located liver tumours at least 15-fold, compared to animals without ultrasound treatments. This study provides the first demonstration of the feasibility of using HTiO2 NPs as sensitizers for sonodynamic therapy in vivo.

Application of Lateral and Distance Spacers in an Oligonucleotide Based Immobilization System for Bioactive Molecules onto Titanium Implants

Immobilization of bioactive molecules (BAMs) on a nanometer scale is of great interest for functionalization of implant and scaffold surfaces in current biomaterials research. A system for immobilization of one or more compounds is described, which is based on nanomechanical fixation of single-stranded nucleic acids into an anodic titanium oxide layer and their subsequent hybridization with BAMs conjugated to the respective complementary strands. This paper focuses on further development and in depth understanding of the immobilization system, as some of the major findings established for common sensor applications for immobilization of single-stranded DNA onto gold surfaces cannot be transferred to the TiO2 surface. The first approach concerning the influence of the internal spacer sequence revealed the best performance for a polyadenine based sequence out of four homologous spacer sequences (A30, T30, C30, and G30). This overall best performance of the A30 spacer is attributed to an increased contour length by nucleotide staggering, which resulted in the best protection of the hybridization sequence from unfavorable interactions with the surface or damaging attacks by reactive oxygen species. The second approach comprises the implementation of a lateral spacer, also based on a homologous sequence of A30. Simultaneous as well as sequential adsorption of anchor strands and spacer strands were performed, and it could be shown that a preadsorption with high density of the spacer was most effective to increase hybridization efficiency.

Preparation of Au-polydopamine functionalized carbon encapsulated Fe₃O₄ magnetic nanocomposites and their application for ultrasensitive detection of carcino-embryonic antigen

A novel carbon encapsulated Fe3O4 nanoparticles embedded in two-dimensional (2D) porous graphitic carbon nanocomposites (Fe3O4@C@PGC nanocomposites) were synthesized by situ synthesis strategy, which provided a sensor platform owing to a large aspect ratio and porous structure. Polydopamine (PDA) were modified on the surface of Fe3O4@C@PGC nanocomposites through self-polymerization of dopamine, acting as both the reductant and template for one-step synthesis of gold nanoparticles. The prepared Au/PDA/Fe3O4@C@PGC nanocomposites show ferromagnetic features, extremely excellent electron transfer, large specific surface area and excellent dispersing property. These are conducive to the electrochemical signal output and the immobilization of antibody. In this work, a highly label-free sensitive magnetic immunosensor was developed based on Au/PDA/Fe3O4@C@PGC nanocomposites for the detection of carcino-embryonic antigen (CEA). The magnetic glassy carbon electrode was used to fix the Au/PDA/Fe3O4@C@PGC nanocomposites with the help of magnetic force. Under the optimal conditions, the immunosensor exhibited a wide linear range (0.001 ng/mL-20.0 ng/mL), a low detection limit (0.33 pg/mL), good reproducibility, selectivity and acceptable stability. The proposed sensing strategy may provide a potential application in the detection of other cancer biomarkers.

Combination of Sonodynamic and Photodynamic Therapy against Cancer Would Be Effective through Using a Regulated Size of Nanoparticles

Nanoparticles have been used for many functional materials in nano-sciences and photo-catalyzing surface chemistry. The titanium oxide nanoparticles will be useful for the treatment of tumor by laser and/or ultrasound as the sensitizers in nano-medicine. We have studied the combination therapy of photo- and sono-dynamic therapies in an animal tumor model. Oral-administration of two sensitizers titanium oxide, 0.2%-TiO2 nanoparticles for sono-dynamic and 1 mM 5-aminolevulinic acid for photodynamic therapies have resulted in the best combination therapeutic effects for the cancer treatment. Our light microscopic and Raman spectroscopic studies revealed that the titanium nanoparticles were distributed inside the blood vessel of the cancer tissue (1-3 μm sizes). Among these nanoparticles with a broad size distribution, only particular-sized particles could penetrate through the blood vessel of the cancer tissue, while other particles may only exhibit the side effects in the model mouse. Therefore, it may be necessary to separate the optimum size particles. For this purpose we have separated TiO2 nanoparticles by countercurrent chromatography with a flat coiled column (1.6 mm ID) immersed in an ultrasonic bath (42 KHz). Separation was performed with a two-phase solvent system composed of 1-butanol-acetic acid-water at a volume ratio of 4:1:5 at a flow rate of 0.1 ml/min. Countercurrent chromatographic separation yielded fractions containing particle aggregates at 31 and 4400 nm in diameter.

Quantification of endocytosis using a folate functionalized silica hollow nanoshell platform

A quantification method to measure endocytosis was designed to assess cellular uptake and specificity of a targeting nanoparticle platform. A simple N -hydroxysuccinimide ester conjugation technique to functionalize 100-nm hollow silica nanoshell particles with fluorescent reporter fluorescein isothiocyanate and folate or polyethylene glycol (PEG) was developed. Functionalized nanoshells were characterized using scanning electron microscopy and transmission electron microscopy and the maximum amount of folate functionalized on nanoshell surfaces was quantified with UV-Vis spectroscopy. The extent of endocytosis by HeLa cervical cancer cells and human foreskin fibroblast (HFF-1) cells was investigated in vitro using fluorescence and confocal microscopy. A simple fluorescence ratio analysis was developed to quantify endocytosis versus surface adhesion. Nanoshells functionalized with folate showed enhanced endocytosis by cancer cells when compared to PEG functionalized nanoshells. Fluorescence ratio analyses showed that 95% of folate functionalized silica nanoshells which adhered to cancer cells were endocytosed, while only 27% of PEG functionalized nanoshells adhered to the cell surface and underwent endocytosis when functionalized with 200 and 900  μg , respectively. Additionally, the endocytosis of folate functionalized nanoshells proved to be cancer cell selective while sparing normal cells. The developed fluorescence ratio analysis is a simple and rapid verification/validation method to quantify cellular uptake between datasets by using an internal control for normalization.

A Near Infrared Light Triggered Hydrogenated Black TiO2 for Cancer Photothermal Therapy

White TiO2 nanoparticles (NPs) have been widely used for cancer photodynamic therapy based on their ultraviolet light-triggered properties. To date, biomedical applications using white TiO2 NPs have been limited, since ultraviolet light is a well-known mutagen and shallow penetration. This work is the first report about hydrogenated black TiO2 (H-TiO2 ) NPs with near infrared absorption explored as photothermal agent for cancer photothermal therapy to circumvent the obstacle of ultraviolet light excitation. Here, it is shown that photothermal effect of H-TiO2 NPs can be attributed to their dramatically enhanced nonradiative recombination. After polyethylene glycol (PEG) coating, H-TiO2 -PEG NPs exhibit high photothermal conversion efficiency of 40.8%, and stable size distribution in serum solution. The toxicity and cancer therapy effect of H-TiO2 -PEG NPs are relative systemically evaluated in vitro and in vivo. The findings herein demonstrate that infrared-irradiated H-TiO2 -PEG NPs exhibit low toxicity, high efficiency as a photothermal agent for cancer therapy, and are promising for further biomedical applications.

Mitochondrial biology, targets, and drug delivery

In recent years, mitochondrial medicine has emerged as a new discipline resting at the intersection of mitochondrial biology, pathology, and pharmaceutics. The central role of mitochondria in critical cellular processes such as metabolism and apoptosis has placed mitochondria at the forefront of cell science. Advances in mitochondrial biology have revealed that these organelles continually undergo fusion and fission while functioning independently and in complex cellular networks, establishing direct membrane contacts with each other and with other organelles. Understanding the diverse cellular functions of mitochondria has contributed to understanding mitochondrial dysfunction in disease states. Polyplasmy and heteroplasmy contribute to mitochondrial phenotypes and associated dysfunction. Residing at the center of cell biology, cellular functions, and disease pathology and being laden with receptors and targets, mitochondria are beacons for pharmaceutical modification. This review presents the current state of mitochondrial medicine with a focus on mitochondrial function, dysfunction, and common disease; mitochondrial receptors, targets, and substrates; and mitochondrial drug design and drug delivery with a focus on the application of nanotechnology to mitochondrial medicine. Mitochondrial medicine is at the precipice of clinical translation; the objective of this review is to aid in the advancement of mitochondrial medicine from infancy to application.

Breaking the depth dependency of phototherapy with Cerenkov radiation and low-radiance-responsive nanophotosensitizers

The combination of light and photosensitizers for phototherapeutic interventions, such as photodynamic therapy, has transformed medicine and biology. However, the shallow penetration of light into tissues and the reliance on tissue oxygenation to generate cytotoxic radicals have limited the method to superficial or endoscope-accessible lesions. Here we report a way to overcome these limitations by using Cerenkov radiation from radionuclides to activate an oxygen-independent nanophotosensitizer, titanium dioxide (TiO2). We show that the administration of transferrin-coated TiO2 nanoparticles and clinically used radionuclides in mice and colocalization in tumours results in either complete tumour remission or an increase in their median survival. Histological analysis of tumour sections showed the selective destruction of cancerous cells and high numbers of tumour-infiltrating lymphocytes, which suggests that both free radicals and the activation of the immune system mediated the destruction. Our results offer a way to harness low-radiance-sensitive nanophotosensitizers to achieve depth-independent Cerenkov-radiation-mediated therapy.