Chitosan-coated ultrapure silicon nanoparticles produced by laser ablation: biomedical potential in nano-oncology as a tumor-targeting nanosystem

Ultrapure silicon nanoparticles (SiNPs) produced by femtosecond laser ablation in water have attracted great interest in the area of cancer therapy as they are efficient as photosensitizers in photodynamic therapy modality and can induce cell hyperthermia under radiofrequency radiation. Recently, we showed that these biocompatible nanoparticles were not able to reach tumors after intravenous injection in mice due to their rapid clearance from the bloodstream. In order to increase their half-life time and therefore their chances to reach and accumulate in tumors by an enhanced permeation retention (EPR) effect, a capping agent on SiNP surface acting as a colloidal stabilizer suspension is required. In this regard, this work focuses for the first time on the functionalization of SiNPs through the modification of their surface by chitosan (SiNPs-CH) in order to enhance their therapeutic properties in cancer therapy. Here, in vivo experiments were carried out during 15 days on nude mice developing a subcutaneously grafted malignant human brain tumor (glioblastoma). The characterization of SiNPs-CH showed an average hydrodynamic size of around 142 ± 65 nm as well as a relatively neutral charge (-5.2 mV) leading to a high colloidal suspension stability. The point of our work concerns the improvement of the biodistribution of SiNPs-CH with regard to tumors, the bloodstream, and organs. After the intravenous administration of 20 mg kg^-1, all the studied parameters (animal behavior, organs' morphology, and histopathology) were in accord with the absence of toxicity due to SiNPs-CH, confirming their biocompatibility and even size and surface charge were modified compared to bare nanoparticles. Moreover an increased time in the bloodstream circulation of up to 7 days was observed, indicating the stealth of the nanoparticles, which could escape opsonization and premature elimination by macrophages and the reticuloendothelial system. As evidenced by silicon assessment, the interaction of the SiNPs-CH with the liver and spleen was significantly reduced compared to the bare nanoparticles. At the same time, SiNPs-CH were concentrated progressively in tumors from 12.03% after 1 day up to 39.55% after 7 days, confirming their uptake by the tumor microenvironment through the enhanced permeability retention effect. Subsequently, the silicon level declined progressively down to 33.6% after 15 days, evidencing the degradation of pH-sensitive SiNPs-CH under the acidic tumor microenvironment. Taken together, the stealthy SiNPs-CH exhibited an ideal biodistribution profile within the tumor microenvironment with a sustainable biodegradation and elimination profile, indicating their promising application in the nano-oncology field as a tumor-targeting system.

Titanate nanotubes as an efficient oral detoxifying agent against drug overdose: application in rat acetaminophen poisoning

Voluntary drug intoxication is mainly due to drug overdose or the interaction of several drugs. Coma and its associated complications such as hypoventilation, aspiration pneumopathy, and heart rhythm disorders are the main hallmarks of drug intoxication. Conventional detoxification treatments, including gastric lavage or vomiting, administration of ipecac or activated charcoal (CH), and the use of antidotes, have proven to be inefficient and are generally associated with severe adverse effects. To overcome these limitations, titanate nanotubes (TiNTs) are proposed as an efficient emerging detoxifying agent because of their tubular shape and high adsorption capacity. In the present study, the detoxifying ability of TiNTs was evaluated on paracetamol (PR)-intoxicated rats. Results indicate that the loading ability of PR into TiNTs (70%) was significantly higher than that recorded for CH (38.6%). In simulated intestinal medium, TiNTs showed a controlled drug release of less than 10% after 72 h of incubation. In PR-intoxicated rats, TiNTs treatment resulted in a 64% decrease of PR after 4 h of poisoning versus 40% for CH. Concomitantly, TiNTs efficiently reduced PR absorption by 90% after 24 h of poisoning, attenuated the elevated levels of biochemical markers (i.e., alanine aminotransferase, aspartate aminotransferase, creatinine, and TNF-α) and mitigated oxidative stress by increasing the activity of superoxide dismutase and reducing the oxidized glutathione/total glutathione ratio, suggesting a histoprotective effect of TiNTs against paracetamol-induced toxicity in rats. In addition to their safety and high stability in the entire gastro-intestinal tract, biodistribution analysis revealed that TiNTs exhibited low intestinal absorption owing to their large cluster size of compact aggregate nanomaterials across the intestinal villi hindering the absorption of paracetamol. Collectively, these data provide a new and promising solution for in vivo detoxification. TiNTs are expected to have great potential for the treatment of voluntary and accidental intoxication in emergency care.

Flumequine-loaded titanate nanotubes as antibacterial agents for aquaculture farms

Flumequine (FLUM), a quinolone-derived antibiotic is one of the most prescribed drugs in aquaculture farms. However, its intensive use becomes worrisome because of its environmental risks and the emergence of FLUM-resistant bacteria. To overcome these problems we propose in this study the encapsulation and the delivery of FLUM by titanate nanotubes (TiNTs). Optimal FLUM loading was reached by suspending the dehydrated powder nanomaterials (FLUM : TiNTs ratio = 1 : 5) in ethanol. The drug entrapment efficiency was calculated to be 80% approximately with a sustained release in PBS at 37 °C up to 5 days. Then FLUM@TiNTs was evaluated for both its in vitro drug release and antimicrobial activity against Escherichia coli (E. coli). Spectacularly high antibacterial activity compared to those of free FLUM antibiotic was obtained confirming the efficiency of TiNTs to protect FLUM from rapid degradation and transformation within bacteria improving thereby its antibacterial effect. Indeed FLUM@TiNTs was efficient to decrease gradually the bacterial viability to reach ≈5% after 5 days versus ≈75% with free FLUM. Finally, the ex vivo permeation experiments on sea bass (Dicentrachus labrax) intestine shows that TiNTs act to increase the intestinal permeation of FLUM during the experiment. Indeed the encapsulated FLUM flux increased 12 fold (1.46 μg cm² h⁻¹) compared to the free antibiotic (0.18 μg cm² h⁻¹). Thanks to its physical properties (diameter 10 nm, tubular shape…) and its high stability in the simulated intestinal medium, TiNTs are easy internalized by enterocytes, thus involving an endocytosis mechanism, and then improve intestinal permeation of FLUM. Taken together, FLUM@TiNTs hold potential as an effective approach for enhancing the antimicrobial activity of FLUM and pave the way not only for future pharmacokinetic studies in the treatment and targeting of fish infections but also for instating of novel strategies that overcome the challenges associated with the abusive use of antibiotics in fish farming.

Flumequine (FLUM), a quinolone-derived antibiotic is one of the most prescribed drugs in aquaculture farms.

Titanium Dioxide Nanotubes as Solid-Phase Extraction Adsorbent for the Determination of Copper in Natural Water Samples

To increase the sensitivity of the analysis method of good copper sample preparation is essential. In this context, an analytical method was developed for sensitive determination of Cu (II) in environmental water samples by using TiO₂ nanotubes as a solid-phase extraction absorbent (SPE). Factors affecting the extraction efficiency including the type, volume, concentration, and flow rate of the elution solvent, the mass of the adsorbent, and the volume, pH, and flow rate of the sample were evaluated and optimized. TiO₂ nanotubes exhibited their good enrichment capacity for Cu (II) (~98%). Under optimal conditions, the method of the analysis showed good linearity in the range of 0–22 mg L⁻¹ (R² > 0.99), satisfactory repeatability (relative standard deviation: RSD was 3.16, n = 5), and a detection limit of about 32.5 ng mL⁻¹. The proposed method was applied to real water samples, and the achieved recoveries were above 95%, showing minimal matrix effect and the robustness of the optimized SPE method.

About the Influence of PEG Spacers on the Cytotoxicity of Titanate Nanotubes-Docetaxel Nanohybrids against a Prostate Cancer Cell Line

The association between chemotherapeutic drugs and metal oxide nanoparticles has sparked a rapidly growing interest in cancer nanomedicine. The elaboration of new engineered docetaxel (DTX)-nanocarriers based on titanate nanotubes (TiONts) was reported. The idea was to maintain the drug inside cancer cells and avoid multidrug resistance mechanisms, which often limit drug efficacy by decreasing their intracellular concentrations in tumor cells. HS-PEGn-COOH (PEG: polyethylene glycol, n = 3000, 5000, 10,000) was conjugated, in an organic medium by covalent linkages, on TiONts surface. This study aimed to investigate the influence of different PEG derivatives chain lengths on the TiONts colloidal stability, on the PEGn density and conformation, as well as on the DTX biological activity in a prostate cancer model (human PC-3 prostate adenocarcinoma cells). In vitro tests highlighted significant cytotoxicities of the drug after loading DTX on PEGn-modified TiONts (TiONts-PEGn-DTX). Higher grafting densities for shorter PEGylated chains were most favorable on DTX cytotoxicity by promoting both colloidal stability in biological media and cells internalization. This promising strategy involves a better understanding of nanohybrid engineering, particularly on the PEGylated chain length influence, and can thus become a potent tool in nanomedicine to fight against cancer.

Assessment of Pharmacokinetics, Toxicity, and Biodistribution of a High Dose of Titanate Nanotubes Following Intravenous Injection in Mice: A Promising Nanosystem of Medical Interest

Titanate nanotubes (TiNTs) produced by the static hydrothermal process present a promising nanosystem for nanomedicine. However, the behavior of these nanotubes in vivo is not yet clarified. In this work, for the first time, we investigated the toxicity of these materials, their pharmacokinetic profile, and their biodistribution in mice. A high dose of TiNTs (45 mg/kg) was intravenously injected in mice and monitored from 6 h to 45 days. The histological examination of organs and the analysis of liver and kidney function markers and then the inflammatory response were in agreement with a long-term innocuity of these nanomaterials. The parameters of pharmacokinetics revealed the rapid clarification of TiNTs from the bloodstream after 6 h of the intravenous injection which then mainly accumulated in the liver and spleen, and their degradation and clearance in these tissues were relatively slow (>4 weeks). Interestingly, an important property of these materials is their slow dissolution under the lysosome acid environment, rendering them biodegradable. It is noteworthy that TiNTs were directly eliminated in urine and bile ducts without obvious toxicity in mice. Altogether, all these typical in vivo tests studying the TiNT pharmacokinetics, toxicity, and biodistribution are supporting the use of these biocompatible nanomaterials in the biomedical field, especially as a nanocarrier-based drug delivery system.

New quercetin-coated titanate nanotubes and their radiosensitization effect on human bladder cancer

Interest in nanostructures such as titanate nanotubes (TNT) has grown notably in recent years due to their biocompatibility and economic viability, making them promising for application in the biomedical field. Quercetin (Qc) has shown great potential as a chemopreventive agent and has been widely studied for the treatment of diseases such as bladder cancer. Motivated by the possibilities of developing a new hybrid nanostructure with potential in biomedical applications, this study aimed to investigate the incorporation of quercetin in sodium (NaTNT) and zinc (ZnTNT) titanate nanotubes, and characterize the nanostructures formed. Qc release testing was also performed and cytotoxicity in Vero and T24 cell lines evaluated by the MTT assay. The effect of TNTs on T24 bladder cancer cell radiosensitivity was also assessed, using cell proliferation and a clonogenic assay. The TNT nanostructures were synthesized and characterized by FESEM, EDS, TEM, FTIR, XRD and TGA. The results showed that the nanostructures have a tubular structure and that the exchange of Na⁺ ions for Zn²⁺ and incorporation of quercetin did not alter this morphology. In addition, interaction between Zn and Qc increased the thermal stability of the nanostructures. The release test showed that maximum Qc delivery occurred after 24 h and the presence of Zn controlled its release. Biological assays indicated that the NaTNTQc and ZnTNTQc nanostructures decreased the viability of T24 cells after 48 h at high concentrations. Furthermore, the clonogenic assay showed that NaTNT, NaTNTQc, ZnTNT and ZnTNTQc combined with 5 Gy reduced the formation of polyclonal colonies of T24 cells after 48 h. The results suggest that the nanostructures synthesized in this study interfere in cell proliferation and can therefore be a powerful tool in the treatment of bladder cancer.

Titanate Nanotubes Engineered with Gold Nanoparticles and Docetaxel to Enhance Radiotherapy on Xenografted Prostate Tumors

Nanohybrids based on titanate nanotubes (TiONts) were developed to fight prostate cancer by intratumoral (IT) injection, and particular attention was paid to their step-by-step synthesis. TiONts were synthesized by a hydrothermal process. To develop the custom-engineered nanohybrids, the surface of TiONts was coated beforehand with a siloxane (APTES), and coupled with both dithiolated diethylenetriaminepentaacetic acid-modified gold nanoparticles (Au@DTDTPA NPs) and a heterobifunctional polymer (PEG₃₀₀₀) to significantly improve suspension stability and biocompatibility of TiONts for targeted biomedical applications. The pre-functionalized surface of this scaffold had reactive sites to graft therapeutic agents, such as docetaxel (DTX). This novel combination, aimed at retaining the AuNPs inside the tumor via TiONts, was able to enhance the radiation effect. Nanohybrids have been extensively characterized and were detectable by SPECT/CT imaging through grafted Au@DTDTPA NPs, radiolabeled with ¹¹¹In. In vitro results showed that TiONts-AuNPs-PEG₃₀₀₀-DTX had a substantial cytotoxic activity on human PC-3 prostate adenocarcinoma cells, unlike initial nanohybrids without DTX (Au@DTDTPA NPs and TiONts-AuNPs-PEG₃₀₀₀). Biodistribution studies demonstrated that these novel nanocarriers, consisting of AuNP- and DTX-grafted TiONts, were retained within the tumor for at least 20 days on mice PC-3 xenografted tumors after IT injection, delaying tumor growth upon irradiation.

Polymer nanocomposites having a high filler content: synthesis, structures, properties, and applications

The recent development of nanoscale fillers, such as carbon nanotubes, graphene, and nanocellulose, allows the functionality of polymer nanocomposites to be controlled and enhanced. However, conventional synthesis methods of polymer nanocomposites cannot maximise the reinforcement of these nanofillers at high filler content. Approaches for the synthesis of high content filler polymer nanocomposites are suggested to facilitate future applications. The fabrication methods address the design of the polymer nanocomposite architecture, which encompasses one, two, and three dimensional morphologies. Factors that hamper the reinforcement of nanostructures, such as alignment, dispersion of the filler and interfacial bonding between the filler and polymer, are outlined. Using suitable approaches, maximum potential reinforcement of nanoscale fillers can be anticipated without limitations in orientation, dispersion, and the integrity of the filler particle-matrix interface. High filler content polymer composites containing emerging materials such as 2D transition metal carbides, nitrides, and carbonitrides (MXenes) are expected in the future.

Taxane-Grafted Metal-Oxide Nanoparticles as a New Theranostic Tool against Cancer: The Promising Example of Docetaxel-Functionalized Titanate Nanotubes on Prostate Tumors

The combination of anticancer drugs and metal oxide nanoparticles is of great interest in cancer nanomedicine. Here, the development of a new nanohybrid, titanate nanotube-docetaxel (TiONts-DTX) is reported, the two parts of which are conjugated by covalent linkages. Unlike most nanoparticles currently being developed for biomedical purposes, TiONts present a needle-shaped morphology. The surface of TiONts is linked with 3-aminopropyl triethoxysilane and with a hetero-bifunctional polymer (polyethylene glycol) to create well-dispersed and biocompatible nanovectors. The prefunctionalized surface of this scaffold has valuable attachments to graft therapeutic agents (DTX in our case) as well as chelating agents (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) to monitor the nanohybrids. To evaluate drug efficacy, in vitro tests have demonstrated that the association between TiONts and DTX shows cytotoxic activity against a hormone-refractory prostate cancer cell line (22Rv1) whereas TiONts without DTX do not. Finally, the first in vivo tests with intratumoral injections show that more than 70% of TiONts nanovectors are retained within the tumor for at least 7 d. Moreover, tumor growth in mice receiving TiONts-DTX is significantly slower than that in mice receiving free DTX. This nanohybrid can thus become a promising new tool in biomedicine to fight against prostate cancer.