Core-Shell Structure Design of Hollow Mesoporous Silica Nanospheres Based on Thermo-Sensitive PNIPAM and pH-Responsive Catechol-Fe3+ Complex

Magnetic Nanoparticles: A Review on Synthesis, Characterization, Functionalization, and Biomedical Applications

Nowadays, magnetic nanoparticles (MNPs) are applied in numerous fields, especially in biomedical applications. Since biofluidic samples and biological tissues are nonmagnetic, negligible background signals can interfere with the magnetic signals from MNPs in magnetic biosensing and imaging applications. In addition, the MNPs can be remotely controlled by magnetic fields, which make it possible for magnetic separation and targeted drug delivery. Furthermore, due to the unique dynamic magnetizations of MNPs when subjected to alternating magnetic fields, MNPs are also proposed as a key tool in cancer treatment, an example is magnetic hyperthermia therapy. Due to their distinct surface chemistry, good biocompatibility, and inducible magnetic moments, the material and morphological structure design of MNPs has attracted enormous interest from a variety of scientific domains. Herein, a thorough review of the chemical synthesis strategies of MNPs, the methodologies to modify the MNPs surface for better biocompatibility, the physicochemical characterization techniques for MNPs, as well as some representative applications of MNPs in disease diagnosis and treatment are provided. Further portions of the review go into the diagnostic and therapeutic uses of composite MNPs with core/shell structures as well as a deeper analysis of MNP properties to learn about potential biomedical applications.

Environmental stimulus-responsive mesoporous silica nanoparticles as anticancer drug delivery platforms

Currently, cancer poses a significant health challenge in the medical community. Traditional chemotherapeutic agents are often accompanied by toxic side effects and limited therapeutic efficacy, restricting their application and advancement in cancer treatment. Therefore, there is an urgent need for developing intelligent drug release systems. Mesoporous silica nanoparticles (MSNs) have many advantages, such as a large specific surface area, substantial pore volume and size, adjustable mesoporous material pore size, excellent biocompatibility, and thermodynamic stability, making them ideal carriers for drug delivery and release. Additionally, they have been widely used to develop novel anticancer drug carriers. Recently, MSNs have been employed to design responsive systems that react to the tumor microenvironment and external stimuli for controlled release of anticancer drugs. This includes factors within the intratumor environment, such as pH, temperature, enzymes, and glutathione as well as external tumor stimuli, such as light, magnetic field, and ultrasound, among others. In this review, we discuss the research progress on environmental stimulus-responsive MSNs in anticancer drug delivery systems, including internal and external environment single stimulus-responsive release and combined stimulus-responsive release. We also summarize the current challenges associated with environmental stimulus-responsive MSNs and elucidate future directions, providing a reference for the functionalization modification and practical application of these MSNs.

Influence of Dopamine Methacrylamide on Swelling Behavior and Nanomechanical Properties of PNIPAM Microgels

The combination of the catechol-containing comonomer dopamine methacrylamide (DMA) with stimuli-responsive poly(N-isopropylacrylamide) (PNIPAM) microgels bears a huge potential in research and for applications due to the versatile properties of catechols. This research gives the first detailed insights into the influence of DMA on the swelling of PNIPAM microgels and their nanomechanical properties. Dynamic light scattering measurements showed that DMA decreases the volume phase transition temperature and completion temperature due to its higher hydrophobicity when compared to NIPAM, while sharpening the transition. The cross-linking ability of DMA decreases the swelling ratios and mesh sizes of the microgels. Microgels adsorbed at the solid surface are characterized by atomic force microscopy─as the DMA content increases, microgels protrude more from the surface. Force spectroscopy measurements below and above the volume phase transition temperature display a stiffening of the microgels with the incorporation of DMA and upon heating across its entire cross section as evidenced by an increase in the E modulus. This confirms the cross-linking ability of DMA. The affine network factor β, derived from the Flory-Rehner theory, is linearly correlated with the E moduli of both pure PNIPAM and P(NIPAM-co-DMA) microgels. However, large DMA amounts hinder the microgel shrinking while maintaining mechanical stiffness, possibly due to catechol interactions within the microgel network.

Loco-regional treatment with temozolomide-loaded thermogels prevents glioblastoma recurrences in orthotopic human xenograft models

Glioblastoma multiforme (GBM) is the most aggressive primary tumor of the central nervous system and the diagnosis is often dismal. GBM pharmacological treatment is strongly limited by its intracranial location beyond the blood-brain barrier (BBB). While Temozolomide (TMZ) exhibits the best clinical performance, still less than 20% crosses the BBB, therefore requiring administration of very high doses with resulting unnecessary systemic side effects. Here, we aimed at designing new negative temperature-responsive gel formulations able to locally release TMZ beyond the BBB. The biocompatibility of a chitosan-β-glycerophosphate-based thermogel (THG)-containing mesoporous SiO₂ nanoparticles (THG@SiO₂) or polycaprolactone microparticles (THG@PCL) was ascertained in vitro and in vivo by cell counting and histological examination. Next, we loaded TMZ into such matrices (THG@SiO₂-TMZ and THG@PCL-TMZ) and tested their therapeutic potential both in vitro and in vivo, in a glioblastoma resection and recurrence mouse model based on orthotopic growth of human cancer cells. The two newly designed anticancer formulations, consisting in TMZ-silica (SiO₂@TMZ) dispersed in the thermogel matrix (THG@SiO₂-TMZ) and TMZ, spray-dried on PLC and incorporated into the thermogel (THG@PCL-TMZ), induced cell death in vitro. When applied intracranially to a resected U87-MG-Red-FLuc human GBM model, THG@SiO₂-TMZ and THG@PCL-TMZ caused a significant reduction in the growth of tumor recurrences, when compared to untreated controls. THG@SiO₂-TMZ and THG@PCL-TMZ are therefore new promising gel-based local therapy candidates for the treatment of GBM.

Hollow Silica Nano and Micro Spheres with Polystyrene Templating: A Mini-Review

Synthesis of monodisperse hollow silica nanospheres, especially using a hard template route, has been shown to be successful, but a high yield is needed for this strategy to be used on an industrial scale. On the other hand, there is a research gap in the synthesis of hollow silica microspheres due to the popularity and easiness of the synthesis of silica nanospheres despite the larger spheres being beneficial in some fields. In this review, current trends in producing hollow silica nanospheres using hard templates, especially polystyrene, are briefly presented. Soft templates have also been used to make highly polydisperse hollow silica spheres, and complex designs have improved polydispersity. The effect of the main parameters on the coating is presented here to provide a basic understanding of the interactions between the silica and template surface in the absence or presence of surfactants. Surface charge, surface modification, parameters in the sol-gel method and interaction between the silica and templates need to be further improved to have a uniform coating and better control over the size, dispersity, wall thickness and porosity. As larger organic templates will have lower surface energy, the efficiency of the micro sphere synthesis needs to be improved. Control over the physical structure of hollow silica spheres will open up many opportunities for them to be extensively used in fields ranging from waste removal to energy storage.

Exogenous nano-silicon application improves ion homeostasis, osmolyte accumulation and palliates oxidative stress in Lens culinaris under NaCl stress

Lentil is one of the highly nutritious legumes but is highly susceptible to salinity stress. Silicon has been known to reduce the effect of various environmental stresses including salinity. Moreover, silicon when applied in its nano-form is expected to augment the beneficial attributes of silicon. However, very little is known regarding the prospect of nano-silicon (nSi) application for alleviating the effect of salinity stress in non-silicified plants like lentil. In this study, the primary objective was to evaluate the efficacy of nSi in the alleviation of NaCl stress during germination and early vegetative stages. In this context, different concentrations of nSi (0, 1, 5, 10 g L-1) was applied along with four different concentrations of NaCl (0, 100, 200, 300 mM). The results indicated the uptake of nSi which was confirmed by the better accumulation of silica in the plant tissues. Most importantly, the enhanced accumulation of silica increased the K+/Na+ ratio of the NaCl-stressed seedlings. Moreover, nSi efficiently improved germination, growth, photosynthetic pigments, and osmotic balance. On the other hand, the relatively reduced activities of antioxidative enzymes were surmounted by the higher activity of non-enzymatic antioxidants which mainly scavenged the increased ROS. Reduced ROS accumulation in return ensured better membrane integrity and reduced electrolyte leakage up on nSi application. Therefore, it can be concluded that the application of nSi (more specifically at 10 g L-1) facilitated the uptake of silica and improved the K+/Na+ ratio to reclaim the growth and physiological status of NaCl-stressed seedlings.

Smart Strategies for Precise Delivery of CRISPR/Cas9 in Genome Editing

The emergence of CRISPR/Cas technology has enabled scientists to precisely edit genomic DNA sequences. This approach can be used to modulate gene expression for the treatment of genetic disorders and incurable diseases such as cancer. This potent genome-editing tool is based on a single guide RNA (sgRNA) strand that recognizes the targeted DNA, plus a Cas nuclease protein for binding and processing the target. CRISPR/Cas has great potential for editing many genes in different types of cells and organisms both in vitro and in vivo. Despite these remarkable advances, the risk of off-target effects has hindered the translation of CRISPR/Cas technology into clinical applications. To overcome this hurdle, researchers have devised gene regulatory systems that can be controlled in a spatiotemporal manner, by designing special sgRNA, Cas, and CRISPR/Cas delivery vehicles that are responsive to different stimuli, such as temperature, light, magnetic fields, ultrasound (US), pH, redox, and enzymatic activity. These systems can even respond to dual or multiple stimuli simultaneously, thereby providing superior spatial and temporal control over CRISPR/Cas gene editing. Herein, we summarize the latest advances on smart sgRNA, Cas, and CRISPR/Cas nanocarriers, categorized according to their stimulus type (physical, chemical, or biological).

Optimization of Nanoparticles for Smart Drug Delivery: A Review

Nanoparticle delivery systems have good application prospects in the treatment of various diseases, especially in cancer treatment. The effect of drug delivery is regulated by the properties of nanoparticles. There have been many studies focusing on optimizing the structure of nanoparticles in recent years, and a series of achievements have been made. This review summarizes the optimization strategies of nanoparticles from three aspects-improving biocompatibility, increasing the targeting efficiency of nanoparticles, and improving the drug loading rate of nanoparticles-aiming to provide some theoretical reference for the subsequent drug delivery of nanoparticles.

Response to "Comment on Bulk Nanobubbles or Not Nanobubbles: That is the Question"

Advanced techniques that combine high spatial resolution with chemical sensitivity to directly probe the observed nanoentities and provide direct evidence that they are truly gas-filled nanobubbles do not exist. Therefore, in our paper, we focused on providing, for the first time, multiple types of indirect evidence using a variety of physical and chemical techniques that the nanoentities are not due to contamination and, hence, they must be bulk nanobubbles (BNBs). It should be noted that such techniques require good experimental skills, sound protocols, good scientific expertise, and reliable equipment. While no single piece of indirect evidence on its own can be considered as conclusive proof, we estimate that our results combined provide strong evidence that bulk nanobubbles do exist and they are stable. The work presented in our paper is the culmination of a series of studies, and many authors have either directly or indirectly confirmed our findings. Nonetheless, in their Comment, Rak & Sedlak reject all of the work we reported. We here address their comments point by point and show that their criticisms are unwarranted and unfounded, as follows.

Glucosamine Modified the Surface of pH-Responsive Poly(2-(diethylamino)ethyl Methacrylate) Brushes Grafted on Hollow Mesoporous Silica Nanoparticles as Smart Nanocarrier

This work presents the synthesis of pH-responsive poly(2-(diethylamino) ethyl methacrylate) (PDEAEMA) brushes anchored on hollow mesoporous silica nanoparticles (HMSN-PDEAEMA) via a surface-initiated ARGET ATRP technique. The average size of HMSNs was ca. 340 nm, with a 90 nm mesoporous silica shell. The dry thickness of grafted PDEAEMA brushes was estimated to be ca 30 nm, as estimated by SEM and TEM. The halogen group on the surface of PDEAMA brushes was successfully derivatized with glucosamine, as confirmed by XPS. The effect of pH on the size of the hybrid nanoparticles was investigated by DLS. The size of fabricated nanoparticle decreased from ca. 950 nm in acidic media to ca. 500 nm in basic media due to the deprotonation of tertiary amine in the PDEAEMA. The PDEAEMA modified HMSNs nanocarrier was efficiently loaded with doxorubicin (DOX) with a loading capacity of ca. 64%. DOX was released in a relatively controlled pH-triggered manner from hybrid nanoparticles. The cytotoxicity studies demonstrated that DOX@HMSN-PDEAEMA-Glucosamine showed a strong ability to kill breast cancer cells (MCF-7 and MCF-7/ADR) at low drug concentrations, in comparison to free DOX.

Recent Advances in Functionalized Mesoporous Silica Frameworks for Efficient Desulfurization of Fuels

Considerable health and climate benefits arising from the use of low-sulfur fuels has propelled the research on desulfurization of fossil fuels. Ideal fuels are urgently needed and are expected to be ultra-low in sulfur (10-15 ppm), with no greater than 50 ppm sulfur content. Although several sulfur removal techniques are available in refineries and petrochemical units, their high operational costs, complex operational needs, low efficiencies, and higher environmental risks render them unviable and challenging to implement. In recent years, mesoporous silica-based materials have emerged as promising desulfurizing agents, owing to their high porosity, high surface area, and easier functionalization compared to conventional materials. In this review, we report on recent progress in the synthesis and chemistry of new functionalized mesoporous silica materials aiming to lower the sulfur content of fuels. Additionally, we discuss the role of special active sites in these sorbent materials and investigate the formulations capable of encapsulating and trapping the sulfur-based molecules, which are challenging to remove due to their complexity, for example the species present in JP-8 jet fuels.