Silica-based organic-inorganic hybrid nanoparticles and nanoconjugates for improved anticancer drug delivery

Natural compounds-based nanomedicines for cancer treatment: Future directions and challenges

Several efforts have been extensively accomplished for the amelioration of the cancer treatments using different types of new drugs and less invasives therapies in comparison with the traditional therapeutic modalities, which are widely associated with numerous drawbacks, such as drug resistance, non-selectivity and high costs, restraining their clinical response. The application of natural compounds for the prevention and treatment of different cancer cells has attracted significant attention from the pharmaceuticals and scientific communities over the past decades. Although the use of nanotechnology in cancer therapy is still in the preliminary stages, the application of nanotherapeutics has demonstrated to decrease the various limitations related to the use of natural compounds, such as physical/chemical instability, poor aqueous solubility, and low bioavailability. Despite the nanotechnology has emerged as a promise to improve the bioavailability of the natural compounds, there are still limited clinical trials performed for their application with various challenges required for the pre-clinical and clinical trials, such as production at an industrial level, assurance of nanotherapeutics long-term stability, physiological barriers and safety and regulatory issues. This review highlights the most recent advances in the nanocarriers for natural compounds secreted from plants, bacteria, fungi, and marine organisms, as well as their role on cell signaling pathways for anticancer treatments. Additionally, the clinical status and the main challenges regarding the natural compounds loaded in nanocarriers for clinical applications were also discussed.

Polysaccharide/Silica Microcapsules Prepared via Ionic Gelation Combined with Spray Drying: Application in the Release of Hydrophilic Substances and Catalysis

Polysaccharide/silica hybrid microcapsules were prepared using ionic gelation followed by spray-drying. Chitosan and alginate were used as biopolymer matrices, and in situ prepared silica was used as a structuring additive. The prepared microparticles were used in two very different applications: the encapsulation of hydrophilic molecules, and as a support for palladium nanoparticles used as catalysts for a model organic reaction, namely the reduction of p-nitrophenol by sodium borhydride. In the first application, erioglaucine disodium salt, taken as a model hydrophilic substance, was encapsulated in situ during the preparation of the microparticles. The results indicate that the presence of silica nanostructures, integrated within the polymer matrix, affect the morphology and the stability of the particles, retarding the release of the encapsulated substance. In the second application, chloropalladate was complexed on the surface of chitosan microparticles, and palladium(II) was subsequently reduced to palladium(0) to obtain heterogeneous catalysts with an excellent performance.

Molecularly Targeted Fluorescent Sensors for Visualizing and Tracking Cellular Senescence

Specific identification and monitoring of senescent cells are essential for the in-depth understanding and regulation of senescence-related life processes and diseases. Fluorescent sensors providing real-time and in situ information with spatiotemporal resolution are unparalleled tools and have contributed greatly to this field. This review focuses on the recent progress in fluorescent sensors for molecularly targeted imaging and real-time tracking of cellular senescence. The molecular design, sensing mechanisms, and biological activities of the sensors are discussed. The sensors are categorized by the types of markers and targeting ligands. Accordingly, their molecular recognition and fluorescent performance towards senescence biomarkers are summarized. Finally, the perspective and challenges in this field are discussed, which are expected to assist future design of next-generation sensors for monitoring cellular senescence.

Internally bridged nanosilica for loadings and release of sparsely soluble compounds

The engineering of a new monodisperse colloid with a sea urchin-like structure with a large complex internal structure is reported, in which silica surfaces are bridged by an aromatic organic cross-linker to serve as a nanocarrier host for drugs such as doxorubicin (DOX) against breast cancer cells. While dendritic fibrous nanosilica (DFNS) was employed and we do not observe a dendritic structure, these particles are referred to as sea urchin-like nanostructured silica (SNS). Since the structure of SNS consists of many silica fibrils protruding from the core, similar to the hairs of a sea urchin. For the aromatic structured cross-linker, bis(propyliminomethyl)benzene (b(PIM)B-S or silanated terephtaldehyde) were employed, which are prepared with terephtaldehyde and 3-aminopropyltriethoxy-silane (APTES) through a simple Schiff base reaction. b(PIM)B-S bridges were introduced into SNS under open vessel reflux conditions. SPS refers to the product obtained by incorporating the cross-linker b(PIM)B-S in ultra-small colloidal SNS particles. In-situ incorporation of DOX molecules resulted in SPS-DOX. The pH-responsive SPS nanocomposites were tested as biocompatible nanocarriers for controllable doxorubicin (DOX) delivery. We conclude that SPS is a unique colloid which has promising potential for technological applications such as advanced drug delivery systems, wastewater remediation and as a catalyst for green organic reactions in water.

Solid-state emitting twisted π-conjugate as AIE-active DSE-gen: in vitro anticancer properties against FaDu and 4T1 with biocompatibility and bioimaging

Dual-state emissive fluorogens (DSE-gens) are currently defining their importance as a transpiring tool in biological and biomedical applications. This work focuses on designing and synthesizing indole-anthracene-based solid-state emitting twisted π-conjugates using a metal-free protocol to achieve AIE-active DSE-gens, expanding their scope in biological applications. Special effort has been made to introduce proficient and photo/thermostable DSE-gens that inhibit cancer but not normal cells. Here, the lead DSE-gen initially detects cancer and normal cells by bioimaging; however, it could also confirm and distinguish cancer cells from normal cells by its abated fluorescence signal after killing cancer cells. In contrast, the fluorescence signals for a normal cell remain unscathed. Surprisingly, these molecules displayed decent anticancer properties against FaDu and 4T1 but not MCF-7 cell lines. From a series of newly designed indole-based molecules, we report one single 2,3,4-trimethoxybenzene-linked DSE-gen (the lead), exhibiting high ROS generation, less haemolysis, and less cytotoxicity than doxorubicin (DOX) for normal cells, crucial parameters for a biocompatible in vitro anticancer probe. Thus, we present a potentially applicable anticancer drug, offering a bioactive material with bioimaging efficacy and a way to detect dead cancer cells selectively. The primary mechanism behind the identified outcomes is deciphered with the support of experimental (steady-state and time-resolved fluorescence, biological assays, cellular uptake) and molecular docking studies.

Oxygen and Drug-Carrying Periodic Mesoporous Organosilicas for Enhanced Cell Viability under Normoxic and Hypoxic Conditions

Over the last decade, inorganic/organic hybrids have been exploited for oxygen-carrying materials and drug delivery. Its low-cost synthesis, controlled shape and size, and stability have made it a viable delivery strategy for therapeutic agents. Rutin (quercetin-3-O-rutinoside) is a bioflavonoid found in fruits and vegetables. Rutin has a variety of pharmaceutical applications, but its low water solubility reduces its stability and bioavailability. As a result, we introduce a new and stable nanosystem for loading a low-soluble drug (rutin) into oxygen-carrying periodic mesoporous organosilicas (PMO-PFCs). Over the course of 14 days, this nanosystem provided a sustained oxygen level to the cells in both normoxic and hypoxic conditions. At different pH values, the drug release (rutin) profile is also observed. Furthermore, the rutin-coated PMO-PFCs interacted with both healthy and malignant cells. The healthy cells have better cell viability on the rutin-coated oxygen-carrying PMO-PFCs, while the malignant cells have a lower cell viability.

Optimized hydration dynamics in mucoadhesive xanthan-based trilayer vaginal films for the controlled release of tenofovir

Karaya gum, pectin and xanthan gum have been tested as candidates for manufacturing mucoadhesive trilayer films containing ethylcellulose and chitosan for the vaginal administration of the antiviral Tenofovir (TFV). The swelling profile correlated with the amount of mobile dipoles determined by impedance spectroscopy allows the determination of the hydration dynamics of these films. The fast water penetration has been demonstrated to favor the formation of polyelectrolyte complexes (PEC) via hydrogen or ionic bonds which would favor a controlled release. The incorporation of an inorganic drug release regulator induces the weakness of the polymeric chains thus enhancing the ionic mobility via the formation of low molecular weight PECs in films manufactured with karaya gum. Due to the different mechanical properties of the individual components, pectin-based films failed for a potential pharmaceutical formulation. However, mucoadhesive trilayer films produced with xanthan gum have demonstrated a moderate swelling, improved wettability and a controlled release of TFV.

Modern Nanocarriers as a Factor in Increasing the Bioavailability and Pharmacological Activity of Flavonoids

This review is devoted to modern systems of nanocarriers that ensure the targeted delivery of flavonoids to various organs and systems. Flavonoids have wide range of effects on the human body due to their antioxidant, anti-inflammatory, antitumor, antimicrobial, antiplatelet and other types of activity. However, the low bioavailability of flavonoids significantly limits their practical application. To overcome this disadvantage, serious efforts have been made in recent years to develop nanoscale carriers for flavonoids. This is particularly important in view of the known antitumor effect of these compounds, which allows them to target tumor cells without affecting surrounding healthy tissues. Nanocarriers provide increased penetration of biologicals into specific organs in combination with controlled and prolonged release, which markedly improves their effectiveness. This review summarizes data on the use of phytosomes, lipid-based nanoparticles, as well as polymeric and inorganic nanoparticles; their advantages and drawbacks are analyzed; the prospect of their use is discussed that opens new possibilities for the clinical application of flavonoids.

Synthesis of Resveratrol Loaded Hybrid Silica-PAMAM Dendrimer Nanoparticles With Emphases on Inducible Nitric Oxide Synthase and Cytotoxicity

Resveratrol is a naturally occurring polyphenolic compound exhibiting therapeutic activities. However, the stability can be altered by UV light, pH and changes in temperature. Encapsulation would be an ideal strategy to improve the stability and bioavailability. Thus, trans-resveratrol (Res) was encapsulated within hybrid nanoparticles consisted with silica and G4 polyamidoamine dendrimer (PAMAM) by sol-gel method. The diameters of synthesized nanoparticles (NPs) were at a range of 212-574 nm and the encapsulation efficiency was 86 %. RAW 264.7 murine macrophage cell line induced with endotoxin/lipopolysaccharide was treated with free resveratrol and Res-loaded NPs for assessing inhibition of inducible nitric oxide synthase (iNOS), where IC₅₀ values of free resveratrol and Res-loaded NPs were 122.68 µM and 249.74 µM. As for cytotoxicity, IC₅₀ values of free resveratrol were found as 176.57 µM and 201.54 µM for MCF-7 and MDA-MB-231 cells, whereas 197.16 µM and 219.07 µM for Res-loaded NPs for the respective cell lines. Overall, sol-gel technique proved to be an ideal technology as can be carried out under mild conditions and Res-loaded NPs have potential to be utilized in the industry.

Quaternary Oxidized Carbon Nanohorns—Based Nanohybrid as Sensing Coating for Room Temperature Resistive Humidity Monitoring

We report the relative humidity (RH) sensing response of a resistive sensor, employing sensing layers, based on a quaternary organic–inorganic hybrid nanocomposite comprising oxidized carbon nanohorns (CNHox), graphene oxide (GO), tin dioxide, and polyvinylpyrrolidone (PVP), at 1/1/1/1 and 0.75/0.75/1/1/1 mass ratios. The sensing structure comprises a silicon substrate, a SiO2 layer, and interdigitated transducer (IDT) electrodes. The sensing film was deposited via the drop-casting method on the sensing structure. The morphology and the composition of the sensing layers were investigated through Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), and RAMAN spectroscopy. The organic–inorganic quaternary hybrid-based thin film’s resistance increased when the sensors were exposed to relative humidity ranging from 0 to 100%. The manufactured devices show a room temperature response comparable to that of a commercial capacitive humidity sensor and characterized by excellent linearity, rapid response and recovery times, and good sensitivity. While the sensor with CNHox/GO/SnO2/PVP at 0.75/0.75/1/1 as the sensing layer has the best performance in terms of linearity and recovery time, the structures employing the CNHox/GO/SnO2/PVP at 1/1/1/1 (mass ratio) have a better performance in terms of relative sensitivity. We explained each constituent of the quaternary hybrid nanocomposites’ sensing role based on their chemical and physical properties, and mutual interactions. Different alternative mechanisms were taken into consideration and discussed. Based on the sensing results, we presume that the effect of the p-type semiconductor behavior of CNHox and GO, correlated with swelling of PVP, dominates and leads to the overall increasing resistance of the sensing layer. The hard–soft acid–base (HSAB) principle also supports this mechanism.

Emerging Nanopharmaceuticals and Nanonutraceuticals in Cancer Management

Nanotechnology is the science of nanoscale, which is the scale of nanometers or one billionth of a meter. Nanotechnology encompasses a broad range of technologies, materials, and manufacturing processes that are used to design and/or enhance many products, including medicinal products. This technology has achieved considerable progress in the oncology field in recent years. Most chemotherapeutic agents are not specific to the cancer cells they are intended to treat, and they can harm healthy cells, leading to numerous adverse effects. Due to this non-specific targeting, it is not feasible to administer high doses that may harm healthy cells. Moreover, low doses can cause cancer cells to acquire resistance, thus making them hard to kill. A solution that could potentially enhance drug targeting and delivery lies in understanding the complexity of nanotechnology. Engineering pharmaceutical and natural products into nano-products can enhance the diagnosis and treatment of cancer. Novel nano-formulations such as liposomes, polymeric micelles, dendrimers, quantum dots, nano-suspensions, and gold nanoparticles have been shown to enhance the delivery of drugs. Improved delivery of chemotherapeutic agents targets cancer cells rather than healthy cells, thereby preventing undesirable side effects and decreasing chemotherapeutic drug resistance. Nanotechnology has also revolutionized cancer diagnosis by using nanotechnology-based imaging contrast agents that can specifically target and therefore enhance tumor detection. In addition to the delivery of drugs, nanotechnology can be used to deliver nutraceuticals like phytochemicals that have multiple properties, such as antioxidant activity, that protect cells from oxidative damage and reduce the risk of cancer. There have been multiple advancements and implications for the use of nanotechnology to enhance the delivery of both pharmaceutical and nutraceutical products in cancer prevention, diagnosis, and treatment.

Indocyanine Green Loaded Modified Mesoporous Silica Nanoparticles as an Effective Photothermal Nanoplatform

Photothermal therapy possesses great advantages for the treatment of drug-resistant tumors. Herein, Near Infrared (NIR)-triggered photothermal nanoparticles were developed through loading indocyanine green (ICG), a kind of NIR dye, into amino group-modified silica nanoparticles (SiO₂-NH₂ NPs). SiO₂-NH₂ NPs were prepared with immobilization of the amino groups into the framework of silica nanoparticles (SiO₂ NPs) by employing (3-aminopropyl)-triethoxysilane (APTES). Before and after the modification of the amino group, the particle sizes of SiO₂ NPs showed similar value, around 100 nm. ICG was further adsorbed into SiO₂-NH₂ NPs by electrostatic attraction to enable SiO₂-NH₂@ICG NPs as a kind of photothermal agent. The loading rate of ICG to SiO₂-NH₂ was greatly increased compared to unmodified SiO₂, and the stability of ICG was also improved. Moreover, the SiO₂-NH₂@ICG NPs exhibited efficient photothermal effects due to ICG transforming laser power into local heat through the connected ICG, when NIR laser irradiation turned on for a couple of minutes. Finally, the in vitro antitumor efficacy of SiO₂-NH₂@ICG NPs was investigated by recording cell proliferation rate and further chronicled the apoptotic morphology evidence by a Calcein-AM/PI fluorescent staining assay, indicating the efficient photothermal targeted therapy for the HepG2 tumor cells.

Recent developments in the use of organic-inorganic nanohybrids for drug delivery

Organic-inorganic nanohybrid (OINH) structures providing a versatile platform for drug delivery with improved characteristics are an area which has gained recent attention. Much effort has been taken to develop these structures to provide a viable treatment options for much alarming diseases such as cancer, bone destruction, neurological disorders, and so on. This review focuses on current work carried out in producing different types of hybrid drug carriers identifying their properties, fabrication techniques, and areas where they have been applied. A brief introduction on understating the requirement for blending organic-inorganic components into a nanohybrid drug carrier is followed with an elaboration given about the different types of OINHs developed currently highlighting their properties and applications. Then, different fabrication techniques are discussed given attention to surface functionalization, one-pot synthesis, wrapping, and electrospinning methods. Finally, it is concluded by briefing the challenges that are remaining to be addressed to obtain multipurpose nanohybrid drug carriers with wider applicability. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies.