pH-responsive drug release and real-time fluorescence detection of porous silica nanoparticles

Curcumin encapsulated in milk small extracellular vesicles as a nanotherapeutic alternative in experimental chronic liver disease

Curcumin is a natural molecule widely tested in preclinical and clinical studies due to its antioxidant and anti-inflammatory activity. Nevertheless, its high hydrophobicity and low bioavailability limit in vivo applications. To overcome curcumin´s drawbacks, small extracellular vesicles (sEVs) have emerged as potential drug delivery systems due to their non-immunogenicity, nanometric size and amphiphilic composition. This work presents curcumin cargo into milk sEV structure and further in vitro and in vivo evaluation as a therapeutic nanoplatform. The encapsulation of curcumin into sEV was performed by two methodologies under physiological conditions: a passive incorporation and active cargo employing saponin. Loaded sEVs (sEVCurPas and sEVCurAc) were fully characterized by physicochemical techniques, confirming that neither methodology affects the morphology or size of the nanoparticles (sEV: 113.3±5.1 nm, sEVCurPas: 127.0±4.5 nm and sEVCurAc: 98.5±3.6 nm). Through the active approach with saponin (sEVCurAc), a three-fold higher cargo was obtained (433.5 µg/mL) in comparison with the passive approach (129.1 µg/mL). These sEVCurAc were further evaluated in vitro by metabolic activity assay (MTT), confocal microscopy, and flow cytometry, showing a higher cytotoxic effect in the tumoral cells RAW264.7 and HepG2 than in primary hepatocytes, specially at high doses of sEVCurAc (4%, 15% and 30% of viability). In vivo evaluation in an experimental model of liver fibrosis confirmed sEVCurAc therapeutic effects, leading to a significant decrease of serum markers of liver damage (ALT) (557 U/L to 338 U/L with sEVCurAc therapy) and a tendency towards decreased liver fibrogenesis and extracellular matrix (ECM) deposition.

A Novel pH-Responsive Iron Oxide Core-Shell Magnetic Mesoporous Silica Nanoparticle (M-MSN) System Encapsulating Doxorubicin (DOX) and Glucose Oxidase (Gox) for Pancreatic Cancer Treatment

Introduction

This study developed a pancreatic cancer targeted drug delivery system that responds to changes in acidity. The system was based on iron oxide core-shell magnetic mesoporous silica nanoparticles (M-MSNs) to treat pancreatic cancer through combined chemotherapy and starvation therapy.

Methods

Glucose oxidase (Gox) was coupled to the cancer cell surface to reduce glucose availability for cancer cells, exacerbating the heterogeneity of the tumor microenvironment. Reduced pH accelerated the depolymerization of pH-sensitive polydopamine (PDA), thereby controlling the spatial distribution of Gox and release of doxorubicin (DOX) within tumor cells.

Results

Characterization results showed the successful synthesis of DG@M-MSN-PDA-PEG-FA (DG@NPs) with a diameter of 66.02 ± 3.6 nm. In vitro data indicated DG@NPs were highly effective and stable with good cellular uptake shown by confocal laser scanning microscopy (CLSM). DG@NPs exhibited high cytotoxicity and induced apoptosis. Additionally, in vivo experiments confirmed DG@NPs effectively inhibited tumor growth in nude mice with good biosafety. The combination of starvation therapy and chemotherapy facilitated drug release, suggesting DG@NPs as a novel drug delivery system for pancreatic cancer treatment.

Conclusion

This study successfully constructed a doxorubicin release system responsive to acidity changes for targeted delivery in pancreatic cancer, providing a new strategy for combination therapy.

Functionalized europium-doped hollow mesoporous silica nanospheres as a cell imaging and drug delivery agents

In an effort to enhance the antitumor efficacy of breast cancer treatment, the chemotherapeutic agent Paclitaxel (PTX) was encapsulated within hyaluronic acid (HA) modified hollow mesoporous silica (HMSNs). In vitro drug release assays showed that the resulting formulation, Eu-HMSNs-HA-PTX, exhibited enzyme-responsive drug release. In addition, cell cytotoxicity and hemolysis assays demonstrated the favorable biocompatibility of both Eu-HMSNs and Eu-HMSNs-HA. Notably, compared to Eu-HMSNs alone, Eu-HMSNs-HA showed enhanced accumulation within CD44-expressing cancer cells (MDA-MB-231). As anticipated, apoptosis experiments indicated that Eu-HMSNs-HA-PTX displayed significantly greater cytotoxicity toward MDA-MB-231 cells than non-targeted Eu-HMSNs-PTX and free PTX. In conclusion, Eu-HMSNs-HA-PTX demonstrated excellent anticancer effects and holds promise as a potent candidate for the efficient therapy of breast cancer.

cRGD-Conjugated GdIO Nanoclusters for the Theranostics of Pancreatic Cancer through the Combination of T1-T2 Dual-Modal MRI and DTX Delivery

Clinically, magnetic resonance imaging (MRI) often uses contrast agents (CAs) to improve image contrast, but single-signal MRI CAs are often susceptible to calcification, hemorrhage, and magnetic sensitivity. Herein, iron acetylacetone and gadolinium acetylacetone were used as raw materials to synthesize a T1-T2 dual-mode imaging gadolinium-doped iron oxide (GdIO) nanocluster. Moreover, to endow the nanoclusters with targeting properties and achieve antitumor effects, the cyclic Arg-Gly-Asp (cRGD) peptide and docetaxel (DTX) were attached to the nanocluster surface, and the efficacy of the decorated nanoclusters against pancreatic cancer was evaluated. The final synthesized material cRGD-GdIO-DTX actively targeted αvβ3 on the surface of Panc-1 pancreatic cancer cells. Compared with conventional passive targeting, the enrichment of cRGD-GdIO-DTX in tumor tissues improved, and the diagnostic accuracy was significantly enhanced. Moreover, the acidic tumor microenvironment triggered the release of DTX from cRGD-GdIO-DTX, thus achieving tumor treatment. The inhibition of the proliferation of SW1990 and Panc-1 pancreatic cancer cells by cRGD-GdIO-DTX was much stronger than that by the untargeted GdIO-DTX and free DTX in vitro. In addition, in a human pancreatic cancer xenograft model, cRGD-GdIO-DTX considerably slowed tumor development and demonstrated excellent magnetic resonance enhancement. Our results suggest that cRGD-GdIO-DTX has potential applications for the precise diagnosis and efficient treatment of pancreatic cancer.

Scalable and High-Performance Radiative Cooling Fabrics through an Electrospinning Method

Reduction in human body temperature under hot conditions is a subject of extensive research. Radiative cooling fabrics have attracted considerable attention because the material reduces body temperature without any energy input, saving both energy and the environment. Researchers have been exploring effective and scalable preparation methods for radiative cooling fabrics. Herein, we employed the electrospinning method to prepare a radiative cooling fabric comprising the poly(vinylidene fluoride-co-hexafluoropropene) nanofiber and SiO₂ nanoparticles. The fabric had a reflectivity exceeding 0.97 in the solar band and an emissivity of over 0.94 within the atmospheric window. The material achieved a radiative cooling effect of 15.9 °C under direct sunlight using a testing device built in-house. The method is simple and scalable and uses abundant and inexpensive raw materials; the technique can help promote the widespread adoption of radiative cooling fabrics.

pH-Responsive Drug Delivery and Imaging Study of Hybrid Mesoporous Silica Nanoparticles

A system of pH-responsive and imaging nanocarriers was developed using mesoporous silica nanoparticles (MSNs), in which gadolinium (Gd) was doped through in situ doping (Gd₂O₃@MSN). Sodium alginate (SA) was attached to the surfaces of the amino groups of MSNs (NH₂-Gd₂O₃@MSN) through the electrostatic adsorption between the amino groups and the carboxyl groups with the formation of hybrid SA-Gd₂O₃@MSN nanoparticles (NPs). The SA-coated NPs were spherical or near-spherical in shape with an average size of nearly 83.2 ± 8.7 nm. The in vitro drug release experiments of a model rhodamine B (RhB) cargo were performed at different pH values. The result confirmed the pH-responsiveness of the nanocarriers. The results of the cytotoxicity studies indicated that the SA-Gd₂O₃@MSN NPs were not cytotoxic by themselves. The results of the in vivo safety evaluation and the hemolysis assay confirmed that the system is highly biocompatible. It is noteworthy that the T1 contrast of the system was significantly enhanced by the Gd, as indicated by the result of the MR imaging. This study confirms that the synthesized hybrid nanosystem is promising for pH-responsive drug delivery and MR imaging for cancer diagnosis and treatment.

Doxorubicin-loaded Mn-doped SiO2 nanospheres coated with carboxymethyl chitosan: fabrication, characterization, and in vitro evaluation

This work describes the preparation of manganese-doped mesoporous silica nanospheres via an in situ doping method. The results of scanning electron microscopy and N2 adsorption demonstrate that mesoporous silica possesses a spherical shape, a highly porous structure, a large specific surface area of 922.21 m2 g−1, and a pore volume of 0.257 cm3 g−1. The mesoporous silica nanocarrier is loaded with doxorubicin, and carboxymethyl chitosan encapsulation is performed to prevent doxorubicin leakage. The easy release characteristics of manganese under acidic conditions and the swelling properties of carboxymethyl chitosan endow the drug-loading system with an excellent pH/responsive release property. A cytotoxicity test shows that mesoporous silica nanospheres–doxorubicin–carboxymethyl chitosan had significant biocompatibility and enhanced cytotoxicity, thus revealing mesoporous silica nanospheres–doxorubicin–carboxymethyl chitosan as a promising delivery system.

Nano‐silica/chitosan composite coatings on biodegradable magnesium alloys for enhanced corrosion resistance in simulated body fluid

Chitosan (CTS) coatings have been studied as a biocompatible coating on biodegradable magnesium (Mg) alloys to improve the corrosion resistance and bioactivity for medical implants. However, the loose structure of the CTS coating cannot provide ideal long‐time corrosion resistance in the physiological environment. In this study, a nano‐SiO2/CTS composite coating was applied on an Mg alloy substrate using the sol–gel method. The surface characteristics of the samples were examined by Fourier‐transform infrared analysis, X‐ray diffraction, scanning electron microscopy‐energy‐dispersive spectrometry, and contact angle measurements. The particle size and suitable dispersion of the SiO2 nanoparticles inside the composite coating were confirmed by transmission electron microscopy. Further, the corrosion protection behavior of the coatings was examined in a simulated body fluid using potentiodynamic polarization, electrochemical impedance spectroscopy, and scanning electrochemical microscopy analyses. Atomic force microscopy was used to determine the surface morphologies of the samples after the polarization test. The surface characteristics, electrochemical measurements, and immersion test revealed that the SiO2 nanoparticles effectively filled the voids of the CTS coating and significantly improved the corrosion resistance. The optimal concentration of nano‐SiO2 is 1.0 g/L.

Zinc oxide nanoparticles: A comprehensive review on its synthesis, anticancer and drug delivery applications as well as health risks

In recent years, zinc oxide nanoparticles (ZnONPs) emerged as an excellent candidate in the field of optical, electrical, food packaging and particularly in biomedical research. ZnONPs show cancer cell specific toxicity via the pH-dependent (low pH) dissolution into Zn²⁺ ions, which generate reactive oxygen species and induce cytotoxicity in cancer cells. Further, ZnONPs have also been used as an effective carrier for the targeted delivery of several anticancer drugs into tumor cells. The increasing focus on ZnONPs resulted in the development of various synthesis approaches including chemical, pHysical, and green or biological for the manufacturing of ZnONPs. In this article, at first we have discussed the various synthesis methods of ZnONPs and secondly its biomedical applications. We have extensively reviewed the anticancer mechanism of ZnONPs on different types of cancers considering its size, shape and surface charge dependent cytotoxicity. Photoirradiation with UV light or NIR laser further increase its anticancer activity via synergistic chemo-photodynamic effect. The drug delivery applications of ZnONPs with special emphasis on drug loading mechanism, stimuli-responsive controlled release and therapeutic effects have also been discussed in this review. Finally, its side effects to vital body organs with mechanism via different exposure routes, the future direction of the ZnONPs research and application are also discussed.

Porous COS@SiO2 Nanocomposites Ameliorate Severe Acute Pancreatitis and Associated Lung Injury by Regulating the Nrf2 Signaling Pathway in Mice

Severe acute pancreatitis (SAP) is associated with high rates of mortality and morbidity. Chitosan oligosaccharides (COSs) are agents with antioxidant properties. We developed porous COS@SiO₂ nanocomposites to study the protective effects and mechanisms of COS nanomedicine for the treatment of acute pancreatitis. Porous COS@SiO₂ nanocomposites released COSs slowly under pH control, enabling sustained release and maintaining the drug at a higher concentration. This study aimed to determine whether porous COS@SiO₂ nanocomposites ameliorate SAP and associated lung injury. The SAP model was established in male C57BL/6 mice by intraperitoneal injection of caerulein. The expression levels of myeloperoxidase, malondialdehyde, superoxide dismutase, nuclear factor-kappa B (NF-κB), the NOD-like receptor protein 3 (NLRP3) inflammasome, nuclear factor E2-related factor 2 (Nrf2), and inflammatory cytokines were detected, and a histological analysis of mouse pancreatic and lung tissues was performed. In the SAP groups, systemic inflammation and oxidative stress occurred, and pathological damage to the pancreas and lung was obvious. Combined with porous COS@SiO₂ nanocomposites before treatment, the systemic inflammatory response was obviously reduced, as were oxidative stress indicators in targeted tissues. It was found that Nrf2 was significantly activated in the COS@SiO₂ treatment group, and the expressions of NF-κB and the NLRP3 inflammasome were notably decreased. In addition, this protective effect was significantly weakened when Nrf2 signaling was inhibited by ML385. This demonstrated that porous COS@SiO₂ nanocomposites activate the Nrf2 signaling pathway to inhibit oxidative stress and reduce the expression of NF-κB and the NLRP3 inflammasome and the release of inflammatory factors, thus blocking the systemic inflammatory response and ultimately ameliorating SAP and associated lung injury.

Long duration stabilization of porous silicon membranes in physiological media: Application for implantable reactors

The natural biodegradabilty of porous silicon (pSi) in physiological media limits its wider usage for implantable systems. We report the stabilization of porous silicon (pSi) membranes by chemical surface oxidation using RCA1 and RCA2 protocols, which was followed by a PEGylation process using a silane-PEG. These surface modifications stabilized the pSi to allow a long period of immersion in PBS, while leaving the pSi surface sufficiently hydrophilic for good filtration and diffusion of several biomolecules of different sizes without any blockage of the pSi structure. The pore sizes of the pSi membranes were between 5 and 20 nm, with the membrane thickness around 70 μm. The diffusion coefficient for fluorescein through the membrane was 2 × 10^-10 cm² s^-1, and for glucose was 2.2 × 10^-9 cm² s^-1. The pSi membrane maintained that level of glucose diffusion for one month of immersion in PBS. After 2 months immersion in PBS the pSi membrane continued to operate, but with a reduced glucose diffusion coefficient. The chemical stabilization of pSi membranes provided almost 1 week stable and functional biomolecule transport in blood plasma and opens the possibility for its short-term implantation as a diffusion membrane in biocompatible systems.

Redox-responsive and pH-sensitive nanoparticles enhanced stability and anticancer ability of erlotinib to treat lung cancer in vivo

Purpose

Erlotinib (ETB) is a well-established therapeutic for non-small-cell lung cancer (NSCLC). To overcome drug resistance and severe toxicities in the clinical application, redox-responsive and pH-sensitive nanoparticle drug delivery systems were designed for the encapsulation of ETB.

Methods

Poly(acrylic acid)-cystamine-oleic acid (PAA-ss-OA) was synthesized. PAA-ss-OA-modified ETB-loaded lipid nanoparticles (PAA-ETB-NPs) were prepared using the emulsification and solvent evaporation method. The tumor inhibition efficacy of PAA-ETB-NPs was compared with that of ETB-loaded lipid nanoparticles (ETB-NPs) and free ETB anticancer drugs in tumor-bearing mice.

Results

PAA-ETB-NPs had a size of 170 nm, with a zeta potential of −32 mV. The encapsulation efficiency and drug loading capacity of PAA-ETB-NPs were over 85% and 2.6%, respectively. In vitro cytotoxicity of ETB-NPs were higher than that of ETB solution. The cytotoxicity of PAA-ETB-NPs was the highest. The in vivo tumor growth inhibition by PAA-ETB-NP treatment was significantly higher than that by ETB-NPs and ETB solution. No obvious weight loss was observed in any of the treatment groups, indicating that all the treatments were well tolerated.

Conclusion

PAA-ETB-NPs could enhance the stability and anti-cancer ability of ETB to treat lung cancer and are a promising drug delivery system for lung cancer treatment.