High-performance method for specific effect on nucleic acids in cells using TiO2~DNA nanocomposites

Synthetic and Biogenic Materials for Oral Delivery of Biologics: From Bench to Bedside

The development of nucleic acid and protein drugs for oral delivery has lagged behind their production for conventional nonoral routes. Over the past decade, the evolution of DNA- and RNA-based technologies combined with the innovation of state-of-the-art delivery vehicles for nucleic acids has brought rapid advancements to the biopharmaceutical field. Nucleic acid therapies have the potential to achieve long-lasting effects, or even cures, by inhibiting or editing genes, which is not possible with conventional small-molecule drugs. However, challenges and limitations must be addressed before these therapies can provide cures for chronic conditions and rare diseases, rather than only offering temporary relief. Nucleic acids and proteins face premature degradation in the acidic, enzyme-rich stomach environment and are rapidly cleared by the liver. To overcome these challenges, various delivery vehicles have been developed to transport therapeutic compounds to the intestines, where the active compounds are released and gut microbiota and mucosal immune system also play an important role. This review provides a comprehensive overview of the promises and pitfalls associated with the oral route of administration of biologics, current delivery systems, applications of orally delivered therapeutics, and the challenges and considerations for translation of nucleic acid and protein therapeutics into clinical practice.

Decoding the role of RNA sequences and their interactions in influenza A virus infection and adaptation

Influenza viruses (types A, B, C, and D) belong to the family orthomyxoviridae. Out of all the influenza types, influenza A virus (IAV) causes human pandemic outbreaks. Its pandemic potential is predominantly attributed to the genetic reassortment favored by a broad spectrum of host species that could lead to an antigenic shift along with a high rate of mutations in its genome, presenting a possibility of subtypes with heightened pathogenesis and virulence in humans (antigenic drift). In addition to antigenic shift and drift, there are several other inherent properties of its viral RNA species (vRNA, vmRNA, and cRNA) that significantly contribute to the success of specific stages of viral infection. In this review, we compile the key features of IAV RNA, such as sequence motifs and secondary structures, their functional significance in the infection cycle, and their overall impact on the virus's adaptive and evolutionary fitness. Because many of these motifs and folds are conserved, we also assess the existing antiviral approaches focused on targeting IAV RNA. This article is categorized under: RNA Structure and Dynamics > Influence of RNA Structure in Biological Systems RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications RNA in Disease and Development > RNA in Disease.

Review of Antimicrobial Properties of Titanium Dioxide Nanoparticles

There is a growing interest in the utilization of metal oxide nanoparticles as antimicrobial agents. This review will focus on titanium dioxide nanoparticles (TiO2 NPs), which have been demonstrated to exhibit high antimicrobial activity against bacteria and fungi, chemical stability, low toxicity to eukaryotic cells, and therefore high biocompatibility. Despite the extensive research conducted in this field, there is currently no consensus on how to enhance the antimicrobial efficacy of TiO2 NPs. The aim of this review is to evaluate the influence of various factors, including particle size, shape, composition, and synthesis parameters, as well as microbial type, on the antibacterial activity of TiO2 NPs against bacteria and fungi. Furthermore, the review offers a comprehensive overview of the methodologies employed in the synthesis and characterization of TiO2 NPs. The antimicrobial activity of TiO2 exhibits a weak dependence on the microorganism species. A tendency towards increased antibacterial activity is observed with decreasing TiO2 NP size. The dependence on the shape and composition is more pronounced. The most pronounced antimicrobial potential is exhibited by amorphous NPs and NPs doped with inorganic compounds. This review may be of interest to specialists in biology, medicine, chemistry, and other related fields.

RNA-Based Vaccines and Therapeutics Against Intracellular Pathogens

RNA-based vaccines have sparked a paradigm shift in the treatment and prevention of diseases by nucleic acid medicines. There has been a notable surge in the development of nucleic acid therapeutics and vaccines following the global approval of the two messenger RNA-based COVID-19 vaccines. This growth is fueled by the exploration of numerous RNA products in preclinical stages, offering several advantages over conventional methods, i.e., safety, efficacy, scalability, and cost-effectiveness. In this chapter, we provide an overview of various types of RNA and their mechanisms of action for stimulating immune responses and inducing therapeutic effects. Furthermore, this chapter delves into the varying delivery systems, particularly emphasizing the use of nanoparticles to deliver RNA. The choice of delivery system is an intricate process involved in developing nucleic acid medicines that significantly enhances their stability, biocompatibility, and site-specificity. Additionally, this chapter sheds light on the current landscape of clinical trials of RNA therapeutics and vaccines against intracellular pathogens.

From Whispering Gallery Mode Resonators to Biochemical Sensors

Optical biosensors are frontrunners for the rapid and real-time detection of analytes, particularly for low concentrations. Among them, whispering gallery mode (WGM) resonators have recently attracted a growing focus due to their robust optomechanical features and high sensitivity, measuring down to single binding events in small volumes. In this review, we provide a broad overview of WGM sensors along with critical advice and additional "tips and tricks" to make them more accessible to both biochemical and optical communities. Their structures, fabrication methods, materials, and surface functionalization chemistries are discussed. We propose this reflection under a pedagogical approach to describe and explain these biochemical sensors with a particular focus on the most recent achievements in the field. In addition to highlighting the advantages of WGM sensors, we also discuss and suggest strategies to overcome their current limitations, leaving room for further development as practical tools in various applications. We aim to provide new insights and combine different knowledge and perspectives to advance the development of the next generation of WGM biosensors. With their unique advantages and compatibility with different sensing modalities, these biosensors have the potential to become major game changers for biomedical and environmental monitoring, among many other relevant target applications.

Antisense Oligonucleotide-Based Therapy of Viral Infections

Nucleic acid-based therapeutics have demonstrated their efficacy in the treatment of various diseases and vaccine development. Antisense oligonucleotide (ASO) technology exploits a single-strand short oligonucleotide to either cause target RNA degradation or sterically block the binding of cellular factors or machineries to the target RNA. Chemical modification or bioconjugation of ASOs can enhance both its pharmacokinetic and pharmacodynamic performance, and it enables customization for a specific clinical purpose. ASO-based therapies have been used for treatment of genetic disorders, cancer and viral infections. In particular, ASOs can be rapidly developed for newly emerging virus and their reemerging variants. This review discusses ASO modifications and delivery options as well as the design of antiviral ASOs. A better understanding of the viral life cycle and virus-host interactions as well as advances in oligonucleotide technology will benefit the development of ASO-based antiviral therapies.

Effective Inhibition of Newly Emerged A/H7N9 Virus with Oligonucleotides Targeted to Conserved Regions of the Virus Genome

Newly emerged highly pathogenic A/H7N9 viruses with pandemic potential are effectively transmitted from birds to humans and require the development of novel antiviral drugs. For the first time, we studied the in vitro and in vivo antiviral activity against A/H7N9 of oligodeoxyribonucleotides (ODNs), which were delivered into the cells in the proposed TiO₂-based nanocomposites (TiO₂∼ODN). The highest inhibition of A/H7N9 in vitro (∼400-fold) and efficient, sequence-specific, and dose-dependent protection (up to 100%) of A/H7N9-infected mice was revealed when ODN was targeted to the conserved terminal 3'-noncoding region of viral (-)RNA. After the treatment with ODN, the virus titer values in the lungs of mice decreased by several orders of magnitude. The TiO₂∼ODN nanocomposite did not show toxicity in mice under the treatment conditions. The proposed approach for effective inhibition of the A/H7N9 can be tested against other viruses, for example, new emerging influenza viruses and coronaviruses with pandemic potential.

Pronounced therapeutic potential of oligonucleotides fixed on inorganic nanoparticles against highly pathogenic H5N1 influenza A virus in vivo

This study describes the effective attack of oligonucleotides on the viral genome of highly pathogenic H5N1 influenza A virus (IAV) in vivo using for the first time the new delivery system consisting of biocompatible low-toxic titanium dioxide nanoparticles and immobilized polylysine-containing oligonucleotides with the native (ODN) and partially modified (ODN_m) internucleotide bonds. Intraperitoneal injection of the TiO₂•PL-ODN nanocomposite provided 65-70% survival of mice, while intraperitoneal or oral administration of TiO₂•PL-ODN_m was somewhat more efficient (~80% survival). The virus titer in the lung was reduced by two-three orders of magnitude. The nanocomposites are nontoxic to mice under the used conditions. TiO₂ nanoparticles, unbound ODN, and the nanocomposite bearing the random oligonucleotide showed an insignificant protective effect, which indicates the ability of targeted oligonucleotides delivered in mice in the nanocomposites to site-specifically interact with complementary RNAs. The protection of oligonucleotides in nanocomposites by TiO₂ nanoparticles and partial modification of the internucleotide bonds provides a continued presence of oligonucleotides in the body for the effective and specific action on the viral RNA. The proposed oligonucleotide delivery system can claim not only to effectively inhibit IAV genes but also to turn off other genes responsible for diseases caused by nucleic acids.

Anti-Influenza Strategies Based on Nanoparticle Applications

Influenza virus has the potential for being one of the deadliest viruses, as we know from the pandemic's history. The influenza virus, with a constantly mutating genome, is becoming resistant to existing antiviral drugs and vaccines. For that reason, there is an urgent need for developing new therapeutics and therapies. Despite the fact that a new generation of universal vaccines or anti-influenza drugs are being developed, the perfect remedy has still not been found. In this review, various strategies for using nanoparticles (NPs) to defeat influenza virus infections are presented. Several categories of NP applications are highlighted: NPs as immuno-inducing vaccines, NPs used in gene silencing approaches, bare NPs influencing influenza virus life cycle and the use of NPs for drug delivery. This rapidly growing field of anti-influenza methods based on nanotechnology is very promising. Although profound research must be conducted to fully understand and control the potential side effects of the new generation of antivirals, the presented and discussed studies show that nanotechnology methods can effectively induce the immune responses or inhibit influenza virus activity both in vitro and in vivo. Moreover, with its variety of modification possibilities, nanotechnology has great potential for applications and may be helpful not only in anti-influenza but also in the general antiviral approaches.

RNA Secondary Structure as a First Step for Rational Design of the Oligonucleotides towards Inhibition of Influenza A Virus Replication

Influenza is an important research subject around the world because of its threat to humanity. Influenza A virus (IAV) causes seasonal epidemics and sporadic, but dangerous pandemics. A rapid antigen changes and recombination of the viral RNA genome contribute to the reduced effectiveness of vaccination and anti-influenza drugs. Hence, there is a necessity to develop new antiviral drugs and strategies to limit the influenza spread. IAV is a single-stranded negative sense RNA virus with a genome (viral RNA—vRNA) consisting of eight segments. Segments within influenza virion are assembled into viral ribonucleoprotein (vRNP) complexes that are independent transcription-replication units. Each step in the influenza life cycle is regulated by the RNA and is dependent on its interplay and dynamics. Therefore, viral RNA can be a proper target to design novel therapeutics. Here, we briefly described examples of anti-influenza strategies based on the antisense oligonucleotide (ASO), small interfering RNA (siRNA), microRNA (miRNA) and catalytic nucleic acids. In particular we focused on the vRNA structure-function relationship as well as presented the advantages of using secondary structure information in predicting therapeutic targets and the potential future of this field.

Ribonucleic acid (RNA) condensation by thermal cycling with metal cations: yield of nanoparticles and their applicability for transfection

To the present, different efficient but expensive, multistage, and time-consuming technologies have been developed to deliver ribonucleic acids (RNA) into eukaryotic cells. Here, we report a simple and feasible solution to design RNA nanocarriers based on nucleic acid condensation by bi- and trivalent metal ions during thermal cycling. Efficient RNA conversion to nanoparticles with small size (10-50 nm) suitable for transfection was achieved using cations Ni²⁺, Co²⁺ or Cu²⁺ alone or in combination with Ca²⁺ at the specially selected concentrations (2.0 mM-3.5 mM), low ionic strength, and narrow pH range (8.0-8.5). Other ions - Mn²⁺, Zn²⁺, Tb³⁺, or Gd³⁺ - caused RNA-cleaving effect that was abolished in the presence of Ni²⁺, Co²⁺, Zn²⁺, or Cu²⁺. Naked RNA-metal ion nanoparticles were extremely unstable in phosphate buffer and sensitive to serum ribonucleases (RNases), and this problem was solved by treatment with polyarginines-16 and 8. Polyarginine-stabilized nanoparticles, containing malachite green (MG) aptamer RNA and metal cations, crossed the cell membrane, dissociated in the cytoplasm, and preserved the functionality of transported RNA, as judged from efficient transfection of human embryonic kidney 293 cells. The technology, involving RNA condensation by metal cations, can be used as a cheap alternative to produce nanoscale carriers to deliver various RNAs into cells in vitro and in vivo.Communicated by Ramaswamy H. Sarma.

Non-agglomerated silicon-organic nanoparticles and their nanocomplexes with oligonucleotides: synthesis and properties

The development of efficient and convenient systems for the delivery of nucleic-acid-based drugs into cells is an urgent task. А promising approach is the use of various nanoparticles. Silica nanoparticles can be used as vehicles to deliver nucleic acid fragments into cells. In this work, we developed a method for the synthesis of silicon-organic (Si-NH2) non-agglomerated nanoparticles by the hydrolysis of aminopropyltriethoxysilane (APTES). The resulting product forms a clear solution containing nanoparticles in the form of low molecular weight polymer chains with [─Si(OH)(C3H6NH2)O─] monomer units. Oligonucleotides (ODN) were conjugated to the prepared Si-NH2 nanoparticles using the electrostatic interaction between positively charged amino groups of nanoparticles and negatively charged internucleotide phosphate groups in oligonucleotides. The Si-NH2 nanoparticles and Si-NH2·ODN nanocomplexes were characterized by transmission electron microscopy, atomic force microscopy and IR and electron spectroscopy. The size and zeta potential values of the prepared nanoparticles and nanocomplexes were evaluated. Oligonucleotides in Si-NH2·ODN complexes retain their ability to form complementary duplexes. The Si-NH2 Flu nanoparticles and Si-NH2·ODNFlu nanocomplexes were shown by fluorescence microscopy to penetrate into human cells. The Si-NH2 Flu nanoparticles predominantly accumulated in the cytoplasm whereas ODNFlu complexes were predominantly detected in the cellular nuclei. The Si-NH2·ODN nanocomplexes demonstrated a high antisense activity against the influenza A virus in a cell culture at a concentration that was lower than their 50% toxic concentration by three orders of magnitude.

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.

Efficient inhibition of influenza A viral replication in cells by deoxyribozymes delivered by nanocomposites

Nucleic-acid-based drugs are a promising class of novel therapeutics; however, their use in medicine is widely limited because of insufficient delivery into cells. This article proposes a new delivery strategy of nucleic acid fragments into cells as components of TiO₂-based nanocomposites. For the first time, unmodified Dz molecules were non-covalently immobilized on TiO₂ nanoparticles precovered with polylysine (TiO₂•PL) with the formation of (TiO₂•PL)•Dz nanocomposites. DNAzymes in the proposed nanocomposites were shown to retain their ability to cleave the RNA target in a cell-free system with the same selectivity as unbound Dz molecules. It was shown by confocal laser microscopy that the fluorescein-labelled (TiO₂•PL)•Dz^Flu nanocomposites penetrate into eukaryotic cells, where Dz^Flu is internalized in the cytoplasm and predominantly in nuclei. Delivery of deoxyribozymes into cells in the proposed nanocomposites permits very efficient interactions with RNA targets inside cells. This was demonstrated by an example of inhibition of H5N1 influenza A virus replication (inhibition by a factor of ca. 3000). This effect was one order of magnitude higher than with using lipofectamine as the transfection agent. The proposed (TiO₂•PL)•Dz nanocomposites demonstrated high antiviral activity and are thus potent as nucleic-acid-based drugs.

Toward Gene Therapy of Hypertension: Experimental Study on Hypertensive ISIAH Rats

TiO₂-based nanocomposites were prepared to deliver oligonucleotides into cells. The nanocomposites were designed by the immobilization of polylysine-containing oligonucleotides on TiO₂-nanoparticles (TiO₂·PL-DNA). We showed for the first time the possibility of using the proposed nanocomposites for treatment of hypertensive disease by introducing them into hypertensive ISIAH rats developed as a model of stress-sensitive arterial hypertension. The mRNA of the gene encoding angiotensin I-converting enzyme (ACE1) involved in the synthesis of angiotensin II was chosen as a target. Administration (intraperitoneal injection and inhalation) of the nanocomposite showed a significant (by 20-30 mm Hg) decrease in systolic blood pressure when the nanocomposite contained the ACE1 gene-targeted oligonucleotide. When using the oligonucleotide with a random sequence, no effect was observed. Further development and improvement of the inhalation nanocomposite drug delivery to systemic hypertensive disease treatment promises new possibilities for clinical practice.

Potential toxicity of engineered nanoparticles in mammalian germ cells and developing embryos: treatment strategies and anticipated applications of nanoparticles in gene delivery

BACKGROUND

Engineered nanoparticles (ENPs) offer technological advantages for a variety of industrial and consumer products as well as show promise for biomedical applications. Recent progress in the field of nanotechnology has led to increased exposure to nanoparticles by humans. To date, little is known about the adverse effects of these ENPs on reproductive health, although interest in nanotechnology area is growing. A few biocompatible ENPs have a high loading capacity for exogenous substances, including drugs, DNA or proteins, and can selectively deliver molecular cargo into cells; however, they represent a potential tool for gene delivery into gametes and embryos.

OBJECTIVE AND RATIONALE

Understanding the reprotoxicological aspects of these ENPs is of the utmost importance to reliably estimate its potential impact on human health. In addition, a search for protective agents to combat ENP-mediated reproductive toxicity is warranted. Therefore, in this review we summarize the toxic effects of a few ENPs (metal and metal oxides, carbon-based nanoparticles, quantum dots and chitosan) in mammalian germ cells and developing embryos, and propose some treatment strategies that could mitigate nanoparticle-mediated toxicity. In addition, we outline the anticipated applications of ENPs in transgenic animal production in order to generate models for investigations into the mechanisms for human disease.

SEARCH METHODS

A literature search was performed using the National Center for Biotechnology Information PubMed database up until March 2016 and relevant keywords were used to obtain information regarding mammalian germ cell-specific toxicity and embryotoxicity of ENPs, possible treatment strategies, as well as the anticipated applications of nanoparticles in gene delivery in germ cells and embryos. Only English language publications were included.

OUTCOMES

Here, we demonstrate the toxicological effects of ENPs in mammalian germ cells and developing embryos by considering both in vitro and in vivo experimental models based on the existing literature. The biodistribution and cellular uptake of ENPs and the observed toxicities are mostly dependent on ENP size and surface-coating agents (surface functional groups/surface charge). ENPs have been shown to induce toxicity via oxidative stress, inflammation and DNA damage in both human and mouse germ cells. Use of antioxidant, anti-inflammatory drugs and selective metal chelators would be beneficial against nanoparticle-induced toxicity.

WIDER IMPLICATIONS

Our review provides the reproductive scientists a mechanistic insight into the reprotoxicological aspects of ENPs to reliably estimate its potential impact on human health and help to select/design protective agents to combat ENP-mediated toxicity. Furthermore, research regarding the detailed mechanism(s) of ENP toxicity in mammalian germ cells and developing embryos as well as the search for protective agents to combat ENP-mediated reproductive toxicity is warranted. Furthermore, we anticipate that investigations into the possibility of applying nanovectors to gene delivery in germ cells and early embryos will open new horizons in reproductive biology.

High antiviral effect of TiO2·PL-DNA nanocomposites targeted to conservative regions of (-)RNA and (+)RNA of influenza A virus in cell culture

Background: The development of new antiviral drugs based on nucleic acids is under scrutiny. An important problem in this aspect is to find the most vulnerable conservative regions in the viral genome as targets for the action of these agents. Another challenge is the development of an efficient system for their delivery into cells. To solve this problem, we proposed a TiO₂·PL-DNA nanocomposite consisting of titanium dioxide nanoparticles and polylysine (PL)-containing oligonucleotides. Results: The TiO₂·PL-DNA nanocomposites bearing the DNA fragments targeted to different conservative regions of (-)RNA and (+)RNA of segment 5 of influenza A virus (IAV) were studied for their antiviral activity in MDCK cells infected with the H1N1, H5N1, and H3N2 virus subtypes. Within the negative strand of each of the studied strains, the efficiency of DNA fragments increased in the direction of its 3'-end. Thus, the DNA fragment aimed at the 3'-noncoding region of (-)RNA was the most efficient and inhibited the reproduction of different IAV subtypes by 3-4 orders of magnitude. Although to a lesser extent, the DNA fragments targeted at the AUG region of (+)RNA and the corresponding region of (-)RNA were also active. For all studied viral subtypes, the nanocomposites bearing the DNA fragments targeted to (-)RNA appeared to be more efficient than those containing fragments aimed at the corresponding (+)RNA regions. Conclusion: The proposed TiO₂·PL-DNA nanocomposites can be successfully used for highly efficient and site-specific inhibition of influenza A virus of different subtypes. Some patterns of localization of the most vulnerable regions in IAV segment 5 for the action of DNA-based drugs were found. The (-)RNA strand of IAV segment 5 appeared to be more sensitive as compared to (+)RNA.

Formation of a thermally stable bilayer of coadsorbed intact and deprotonated thymine exploiting the surface corrugation of rutile TiO2(110)

Adsorption of thymine on rutile TiO₂(110) leads to a room temperature stable bilayer which follows the corrugation of the oxide surface and consists of both intact and deprotonated molecules.

[Eficient inhibition of human influenza A virus by oligonucleotides electrostatically fixed on polylysine-containing TiO2 nanoparticles]

Antiviral activity of TiO2 * PL * DNA nanobiocomposites was studied on the MDCK cell culture infected with influenza A virus (subtype H3N2). DNA fragments in the nanocomposites are electrostatically bound to titanium dioxide nanoparticles pre-covered with polylysine. It was shown that TiO2 * PL * DNA(v3') nanocomposite bearing the DNA(v3') fragment targeted to the 3'-end of the noncoding region of segment 5 of viral RNA specifically inhibited the virus reproduction with the efficiency of 99.8 and 99.9% (or by factors of~400 and 1000) at a low concentration of DNA(v3') in nanocomposite (0.1 and 0.2 µM, respectively). The TiO2 * PL * DNA(r) nanocomposite containing oligonucleotide noncomplementary to viral RNA or the oligonucleotide unbound to the nanoparticles show very low antiviral activity (inhibition by factors of~3.5 and 1.3, respectively).

Knockdown of different influenza A virus subtypes in cell culture by a single antisense oligodeoxyribonucleotide

Influenza is a heavy socially significant viral infection that affects humans, birds, and wild and domestic animals. The threat of existing and new highly pathogenic subtypes of influenza A virus (IAV) makes it necessary to develop an effective drug that may affect different IAV strains. For this purpose, oligodeoxynucleotides (DNA fragments) attached to titanium dioxide (TiO2) nanoparticles through a polylysine linker, forming TiO2·PL-DNA nanocomposites, that penetrated into cells without transfection agents were used. For the first time, efficient (≥99.9%) suppression of the reproduction of different subtypes of IAV, including highly pathogenic H5N1 and H1N1, was achieved. These results were obtained using the TiO2·PL-DNA nanocomposite bearing a single antisense oligodeoxynucleotide (0.1μM) targeted to the conserved 3'-noncoding region of RNA segment 5, which is common to all tested strains. Very efficient suppression of the reproduction of different subtypes of IAV was probably achieved due to the use of the proposed delivery system for oligonucleotides in the form of the TiO2·PL-DNA nanocomposites. These results indicate the possibility of creating an efficient drug to affect existing and newly emerging pathogenic IAV strains.

Investigation of the antibacterial effects of silver-modified TiO2 and ZnO plasmonic photocatalysts embedded in polymer thin films

Nanosilver-modified TiO2 and ZnO photocatalysts were studied against methicillin-resistant Staphylococcus aureus on the surface and against naturally occurring airborne microorganisms. The photocatalysts/polymer nanohybrid films were prepared by spray coating technique on the surface of glass plates and on the inner surface of the reactive light source. The photoreactive surfaces were activated with visible light emitting LED light at λ = 405 nm. The optical properties of the prepared photocatalyst/polymer nanohybrid films were characterized by diffuse reflectance measurements. The photocatalytic properties were verified with the degradation of ethanol by gas chromatography measurements. The destruction of the bacterial cell wall component was examined with transmission electron microscope. The antibacterial effect of the photocatalyst/polymer nanohybrid films was tested with different methods and with the associated standard ISO 27447:2009. With the photoreactive coatings, an extensive disinfectant film was developed and successfully prepared. The cell wall component of S. aureus was degraded after 1 h of illumination. The antibacterial effect of the nanohybrid films has been proven by measuring the decrease of the number of methicillin-resistant S. aureus on the surface and in the air as the function of illumination time. The photocatalyst/polymer nanohybrid films could inactivate 99.9 % of the investigated bacteria on different thin films after 2 h of illumination with visible light source. The reactive light source with the inner-coated photocatalyst could kill 96 % of naturally occurring airborne microorganisms after 48 h of visible light illumination in indoor air sample. The TEM results and the microbiological measurements were completed with toxicity tests carried out with Vibrio fischeri bioluminescence bacterium.

Adsorption of DNA oligonucleotides by titanium dioxide nanoparticles

Titanium dioxide (TiO2) or titania shows great promise in detoxification and drug delivery. To reach its full potential, it is important to interface TiO2 with biomolecules to harness their molecular recognition function. To this end, DNA attachment is an important topic. Previous work has mainly focused on long double-stranded DNA or single nucleotides. For biosensor development and targeted drug delivery, it is more important to use single-stranded oligonucleotides. Herein, the interaction between fluorescently labeled oligonucleotides and TiO2 nanoparticles is reported. The point of zero charge (PZC) of TiO2 is around 6 in water or acetate buffer; therefore, the particles are positively charged at lower pH. However, if in phosphate or citrate buffer, the particles are negatively charged, even at pH ∼2, suggesting strong adsorption of buffer anions. DNA adsorption takes place mainly via the phosphate backbone, although the bases might also have moderate contributions. Peptide nucleic acids (PNAs) with an amide backbone cannot be adsorbed. DNA adsorption is strongly affected by inorganic anions, where phosphate and citrate can strongly inhibit DNA adsorption. DNA adsorption is promoted by adding salt or lowering pH. DNA adsorption is accompanied with fluorescence quenching, and double-stranded DNA showed reduced quenching, allowing for the detection of DNA using TiO2 nanoparticles.