pH-triggered degradation and release of doxorubicin from zeolitic imidazolate framework-8 (ZIF8) decorated with polyacrylic acid

Preparation of Metal-Polyphenol Modified Zeolitic Imidazolate Framework-8 Nanoparticles for Cancer Drug Delivery

With the rising incidence of cancer, chemotherapy has become a widely used treatment approach. However, the use of anticancer drugs such as doxorubicin (DOX) poses significant long-term risks due to its nonspecific distribution and severe side effects. Therefore, developing a nanoparticle-based drug delivery system (DDS) that enhances the bioavailability of DOX specifically to cancer cells is crucial while minimizing its side effects on normal cells. This study employed zeolitic imidazolate framework-8 (ZIF-8) as a DDS to encapsulate DOX using a one-pot method. The surface of this system was subsequently modified with a copper-gallic acid (Cu-GA) complex to form the Cu-GA/DOX@ZIF-8 (CGDZ) system. The CGDZ system effectively encapsulates DOX and demonstrates pH-responsive drug release, facilitating controlled drug release in the acidic environment of cancer cells. Furthermore, the Cu-GA coating enhances the biocompatibility of the material, reduces drug toxicity in normal endothelial cells (BAECs) due to the antioxidant feature of modified GA, and maintains the efficacy and intracellular trafficking of DOX in colon cancer cells (C-26). Interestingly, CGDZ nanoparticles showed significantly higher toxicity against cancer cells as compared to unmodified systems and free DOX. Overall, CGDZ exhibited significant in vitro efficacy in targeting cancer cell lines while reducing the toxicity of DOX, offering a novel and effective nanoparticle system for targeted cancer treatment.

Revolutionary NIR-activated silicon nanoparticles: precision-controlled release and targeted 3D cancer cell destruction

In cancer therapy, controlled and targeted drug release systems are essential to maximize therapeutic outcomes while minimizing adverse effects. This study introduces an innovative mesoporous silicon nanoparticle (MSN) platform, functionalized with the natural anticancer agent dieckol (Di) and designed for precise drug delivery activated by near-infrared (NIR) irradiation. By embedding Di and grafting fluorescent organic conjugates onto the MSN surface, this innovative nanocarrier demonstrates exceptional sensitivity to NIR stimuli and potent chemo-photothermal effects. Notably, drug release remains stable across different pH conditions (7.4, 6.5, and 5.5), ensuring consistent therapeutic delivery. However, upon NIR exposure, the release can be selectively accelerated, enabling precise, real-time, and on-demand drug release control for enhanced treatment efficacy. Cytotoxicity tests revealed that IPSi-Dox-Di-DQA nanoparticles exhibited potent dose-dependent inhibition of cancer cell growth (SH-SY5Y and B16-F10), while sparing healthy cells (HEK-293), highlighting their specificity. Furthermore, advanced 3D cell viability assays mimic the complexities of in vivo cancer environments, with spheroid disintegration under nanoparticle treatment underscoring the platform's powerful anticancer potential. These findings position IPSi-Dox-Di-DQA nanoparticles as a promising frontier in the development of selective, effective cancer therapeutics through synergistic NIR-controlled drug release and mitochondrial targeting.

Surface Coating of ZIF-8 Nanoparticles with Polyacrylic Acid: A Facile Approach to Enhance Chemical Stability for Biomedical Applications

Nanoparticles of zeolitic imidazole framework-8 (ZIF-8 NPs), which are the subclass of metal-organic frameworks consisting of Zn ion and 2-methylimidazole, have been identified as promising drug carriers since their large microporous structure is suited for encapsulating hydrophobic drug molecules. However, one of the limitations of ZIF-8 NPs is their low stability in physiological solutions, especially in the presence of water and phosphate anions. These molecules can interact with the coordinatively unsaturated Zn sites at the external surface to induce the degradation of ZIF-8 NPs. In this study, herein a facile approach is reported to enhance the chemical stability of ZIF-8 NPs by surface coating with polyacrylic acid (PAA). The PAA-coated ZIF-8 (PAA-ZIF-8) NPs are prepared by mixing ZIF-8 NPs and PAA in water. PAA coating inhibits the degradation of ZIF-8 NPs in water as well as phosphate-buffered saline over 6 days, which seems to be due to the coordination of carboxyl groups of PAA to the reactive Zn sites. Furthermore, the PAA-ZIF-8 NPs loaded with the anticancer drug doxorubicin (Dox) show cytotoxicity in human colon cancer cells. These results clearly show the feasibility of the PAA coating approach to improve the chemical stability of ZIF-8 NPs without impairing their drug delivery capability.

Optimizing adsorption and photocatalysis for tetracycline and sulfamethoxazole removal: the role of Ag+ and NH4 + in Bi-MOF derivatives

This study focuses on the synthesis, characterization, and evaluation of the photocatalytic efficiency of bismuth-based metal-organic frameworks (Bi-MOFs) and their derivatives, specifically Ag+/Bi-MOF and NH4 +/Ag+/Bi-MOF, in the degradation of tetracycline (TC) and sulfamethoxazole (SMX) under visible light irradiation. Bi-MOFs are promising photocatalysts due to their large surface area, tunable porosity, and unique electronic properties that are favorable for visible light absorption. In this study, Bi-MOFs were synthesized using a solvothermal method, with the incorporation of silver (Ag+) and ammonium (NH4 +) ions to enhance their photocatalytic performance. The photocatalytic activity of Bi-MOF, Ag/Bi-MOF, and NH4 +/Ag+/Bi-MOF was evaluated by measuring the degradation rates of TC and SMX in aqueous solutions under visible light. The experiments demonstrated that Bi-MOFs effectively degraded both antibiotics, with the Ag/Bi-MOF derivative showing superior performance due to improved charge separation and light absorption. NH4 +/Ag+/Bi-MOF also exhibited significant photocatalytic activity, influenced by the presence of ammonium ions, which altered the surface chemistry of the catalyst and affected the adsorption and degradation processes. Reusability tests confirmed that these photocatalysts maintained high degradation efficiency over multiple cycles, highlighting their potential for practical environmental applications. This research provides a sustainable and effective solution for the removal of persistent organic pollutants such as TC and SMX.

Effect of pore structure in bismuth metal-organic framework nanorod derivatives on adsorption and organic pollutant degradation

This study explores the synthesis, characterization, and photocatalytic properties of bismuth metal-organic framework (Bi-MOF) nanorods and their derivatives such as Ag/Bi-MOF and Ag/Bi2O3. Bi-MOF nanorods exhibit significant photocatalytic activity under visible light, with the addition of silver (Ag) enhancing electron-hole pair separation and reducing their recombination. This leads to improved photocatalytic performance, particularly in the degradation of organic pollutants such as Rhodamine B (RhB) and Methylene Blue (MB). The results show that Bi-MOF and its derivatives demonstrate excellent chemical stability and high performance in photocatalytic applications, even when subjected to high temperatures and tested across a wide pH range. The large surface area and microporous structure facilitate selective adsorption of small organic molecules like MB. The pores and large surface area not only provide numerous active sites but also enhance the interaction between reactants and the catalyst surface, improving photocatalytic efficiency. Bi-MOF and its derivatives perform optimally across a broad pH range, from acidic to alkaline environments, where strong oxidizing hydroxyl radicals (·OH) are easily formed, aiding in the effective degradation of organic compounds. The study also shows that Bi-MOF and its derivatives can be reused multiple times without significant loss in performance. This research contributes to the development of advanced materials for environmental remediation, highlighting the potential of Bi-MOF-based nanocomposites in practical applications.

Enhanced anti-tumor and anti-metastatic activity of quercetin using pH-sensitive Alginate@ZIF-8 nanocomposites:in vitroandin vivostudy

Quercetin (Qc) possesses anti-cancer properties, such as cell signaling, growth suppression, pro-apoptotic, anti-proliferative, and antioxidant effects. In this study, we developed an alginate-modified ZIF-8 (Alg@ZIF-8) to enhance the anti-tumor efficacy of Qc. The developed alginate-modified quercetin-loaded ZIF-8 (Alg@Qc@ZIF-8) was characterized using scanning electron microscope (SEM), dynamic light scattering (DLS), fourier transform infrared spectroscopy Thermogravimetric analysis, Brunauer-Emmett-Teller, and x-ray diffraction. The drug release pattern was evaluated at pH 5.4 and 7.4. The cytotoxicity of nanoparticles was assessed on the 4T1 cell line. Finally, the anti-tumor activity of Alg@Qc@ZIF-8 was evaluated in 4T1 tumor-bearing mice. SEM showed that the nanoparticles were spherical with a diameter of mainly below 50 nm. The DLS showed that the developed nanoparticles' hydrodynamic diameter, zeta potential, and polydispersity index were 154.9 ± 7.25 nm, -23.8 ± 5.33 mV, and 0.381 ± 0.09, respectively. The drug loading capacity was 10.40 ± 0.02%. Alg@Qc@ZIF-8 exhibited pH sensitivity, releasing more Qc at pH 5.4 (about 3.62 times) than at pH 7.4 after 24 h. Furthermore, the IC50value of Alg@Qc@ZIF-8 on the 4T1 cell line was 2.16 times lower than net Qc. Importantly, in tumor-bearing mice, Alg@Qc@ZIF-8 demonstrated enhanced inhibitory effects on tumor growth and lung metastasis compared to net Qc. Considering thein vitroandin vivooutcomes, Alg@Qc@ZIF-8 might hold great potential for effective breast cancer management.

Optimized Epigallocatechin Gallate Delivery and Adipogenesis Inhibition through Fluorescent Mesoporous Nanocarriers

Epigallocatechin gallate (EGCG), a naturally occurring compound known for its multiple health benefits including antioxidant, anti-inflammatory, cancer preventive, and weight management effects, faces challenges due to its inherent instability and limited bioavailability. To address these limitations, our study pioneers an investigation into the unique behavior of EGCG, revealing its degradation into epicatechin (EGC) and gallic acid (GA) during the drug delivery process. In this research, we use fluorescent mesoporous silica nanoparticles (FMSNs) as a sophisticated delivery system for EGCG. This innovative approach aims to not only enhance the stability of EGCG but also regulate its sustained release dynamics to enable prolonged cellular activity. To comprehensively evaluate our novel delivery strategy, we performed assays to assess both the antioxidant potential and its impact on lipid inhibition using Oil Red O. The results not only underscore the potential of FMSN-based nanocarriers for efficient EGCG delivery but also reveal groundbreaking insights into its enzymatic degradation, a previously unexplored facet. This research substantially advances our understanding of EGCG's behavior during delivery and offers a promising avenue for improving its therapeutic efficacy and expanding its applications in health management.

Co-delivery of carboplatin and doxorubicin using ZIF-8 coated chitosan-poly(N-isopropyl acrylamide) nanoparticles through a dual pH/thermo responsive strategy to breast cancer cells

A dual pH/temperature sensitive core-shell nanoformulation has been developed based on ZIF-8 coated with chitosan-poly(N-isopropyl acrylamide) (CS-PNIPAAm) for co-delivery of doxorubicin (DOX) and carboplatin (CBP) in breast cancer cells. The resulting nanoparticles (NPs) had particle sizes around 200 nm and a zeta potential of about +30 mV. The CBP and DOX loading contents in the final NPs were 11.6 % and 55.54 %, respectively. NPs showed a pH and thermoresponsive drug release profile with a sustained prolonged release under physiological conditions. The in vitro cytotoxicity experiments showed a significant synergism of CBP and DOX to induce the IC50 of 1.96 μg/mL in MCF-7 cells and 4.54 μg/mL in MDA-MB-231 cells. Also, the final NPs were safer than free DOX and CBP on normal cells. The in vitro study confirmed the higher potency of the designed NPs in combination therapy against breast cancer cells with lower side effects than free drugs.

Breaking Osteoclast-Acid Vicious Cycle to Rescue Osteoporosis via an Acid Responsive Organic Framework-Based Neutralizing and Gene Editing Platform

In the osteoporotic microenvironment, the acidic microenvironment generated by excessive osteoclasts not only causes irreversible bone mineral dissolution, but also promotes reactive oxygen species (ROS) production to induce osteoblast senescence and excessive receptor activator of nuclear factor kappa-B ligand (RANKL) production, which help to generate more osteoclasts. Hence, targeting the acidic microenvironment and RANKL production may break this vicious cycle to rescue osteoporosis. To achieve this, an acid-responsive and neutralizing system with high in vivo gene editing capacity is developed by loading sodium bicarbonate (NaHCO3) and RANKL-CRISPR/Cas9 (RC) plasmid in a metal-organic framework. This results showed ZIF8-NaHCO3@Cas9 (ZNC) effective neutralized acidic microenvironment and inhibited ROS production . Surprisingly, nanoparticles loaded with NaHCO3 and plasmids show higher transfection efficiency in the acidic environments as compared to the ones loaded with plasmid only. Finally, micro-CT proves complete reversal of bone volume in ovariectomized mice after ZNC injection into the bone remodeling site. Overall, the newly developed nanoparticles show strong effect in neutralizing the acidic microenvironment to achieve bone protection through promoting osteogenesis and inhibiting osteolysis in a bidirectional manner. This study provides new insights into the treatment of osteoporosis for biomedical and clinical therapies.

Ligand Desorption and Fragmentation in Oleate-Capped CdSe Nanocrystals under High-Intensity Photoexcitation

Semiconductor nanocrystals (NCs) offer prospective use as active optical elements in photovoltaics, light-emitting diodes, lasers, and photocatalysts due to their tunable optical absorption and emission properties, high stability, and scalable solution processing, as well as compatibility with additive manufacturing routes. Over the course of experiments, during device fabrication, or while in use commercially, these materials are often subjected to intense or prolonged electronic excitation and high carrier densities. The influence of such conditions on ligand integrity and binding remains underexplored. Here, we expose CdSe NCs to laser excitation and monitor changes in oleate that is covalently attached to the NC surface using nuclear magnetic resonance as a function of time and laser intensity. Higher photon doses cause increased rates of ligand loss from the particles, with upward of 50% total ligand desorption measured for the longest, most intense excitation. Surprisingly, for a range of excitation intensities, fragmentation of the oleate is detected and occurs concomitantly with formation of aldehydes, terminal alkenes, H2, and water. After illumination, NC size, shape, and bandgap remain constant although low-energy absorption features (Urbach tails) develop in some samples, indicating formation of substantial trap states. The observed reaction chemistry, which here occurs with low photon to chemical conversion efficiency, suggests that ligand reactivity may require examination for improved NC dispersion stability but can also be manipulated to yield desired photocatalytically accessed chemical species.

A new era in cancer treatment: harnessing ZIF-8 nanoparticles for PD-1 inhibitor delivery

This review delves into the potential of zeolitic imidazolate framework-8 (ZIF-8) nanoparticles in augmenting the efficacy of cancer immunotherapy, with a special focus on the delivery of programmed cell death receptor 1 (PD-1) inhibitors. The multifunctional nature of ZIF-8 nanoparticles as drug carriers is emphasized, with their ability to encapsulate a range of therapeutic agents, including PD-1 inhibitors, and facilitate their targeted delivery to tumor locations. By manipulating the pore size and surface characteristics of ZIF-8 nanoparticles, controlled drug release can be realized. The strategic use of ZIF-8 nanoparticles to deliver PD-1 inhibitors presents a precise and targeted modality for cancer treatment, reducing off-target impacts and enhancing therapeutic effectiveness. This combined strategy addresses the existing challenges and constraints of current immunotherapy techniques, with the ultimate goal of enhancing patient outcomes in cancer therapy.

Aptamer and DNAzyme-Functionalized Cu-MOF Hybrid Nanozymes for the Monitoring and Management of Bacteria-Infected Wounds

Metal-organic frameworks (MOFs) with peroxidase (POD)-like activity have great potential for combating drug-resistant bacterial infections. However, the use of POD-like activities is severely limited by low oxygen levels and high levels of glutathione (GSH) within the microenvironment of bacterial infection. Herein, G-quadruplex/hemin DNAzyme-aptamer probes and tannic acid-chelated Au nanoparticle (Au-TA)-decorated Cu-based MOF nanosheets (termed GATC) with triple-enzyme activities were developed for visual detection and efficient antibacterial therapy. First, the monometallic MOFs (Cu-ZIF) showed the best catalytic and loading capacity performance compared with the bimetallic MOFs (CoCu-ZIF and ZnCu-ZIF). Then, Cu-MOFs, Au-TA, and DNAzyme improve the POD-like activity to generate more hydroxyl radicals (•OH) to kill bacteria. GATC can bind to bacteria through aptamer recognition, increasing the bacterial surface contact area for efficient antibacterial activity. GATC can decompose H2O2 into O2 to alleviate hypoxia and improve the microenvironment due to its catalase (CAT)-like activity. In addition, GATC exhibited GSH peroxidase-like activity, which can avoid the loss of •OH and result in bacterial death more easily. Compared with previous studies, GATC exhibited extraordinary bactericidal ability at an extremely low dosage of 3 μg/mL against methicillin-resistant Staphylococcus aureus (MRSA). Notably, the GATC-catalyzed chromogenic reaction could accurately monitor the MRSA infection treatment process. Overall, this work could establish a therapeutic platform for the monitoring and management of bacteria-infected wounds.

Delivery of Chemotherapy Agents and Nucleic Acids with pH-Dependent Nanoparticles

With less than one percent of systemically injected nanoparticles accumulating in tumors, several novel approaches have been spurred to direct and release the therapy in or near tumors. One such approach depends on the acidic pH of the extracellular matrix and endosomes of the tumor. With an average pH of 6.8, the extracellular tumor matrix provides a gradient for pH-responsive particles to accumulate, enabling greater specificity. Upon uptake by tumor cells, nanoparticles are further exposed to lower pHs, reaching a pH of 5 in late endosomes. Based on these two acidic environments in the tumor, various pH-dependent targeting strategies have been employed to release chemotherapy or the combination of chemotherapy and nucleic acids from macromolecules such as the keratin protein or polymeric nanoparticles. We will review these release strategies, including pH-sensitive linkages between the carrier and hydrophobic chemotherapy agent, the protonation and disruption of polymeric nanoparticles, an amalgam of these first two approaches, and the release of polymers shielding drug-loaded nanoparticles. While several pH-sensitive strategies have demonstrated marked antitumor efficacy in preclinical trials, many studies are early in their development with several obstacles that may limit their clinical use.

Composite beads from chitosan and zeolitic imidazolate framework-8 for the adsorption and photocatalytic degradation of reactive red 141

This study describes the fabrication of composite beads comprising chitosan and zeolitic imidazolate framework-8 (ZIF-8) as a natural biodegradable dye adsorbent and support for ZnO photocatalyst. Chitosan beads were cross-linked with trisodium citrate dihydrate to enhance the adsorption capacity for the reactive red 141 dye (RR141). The ability was further improved by adding ZIF-8. The optimum loading was 2.5%, and the adsorption equilibrium was reached within 2 h. The maximum adsorption capacity of the composite beads was 6.51 mg g-1 at pH 4 when an initial concentration of 1000 mg L-1 was used. The pseudo-second-order kinetics model and the Langmuir isotherm model best described the adsorption process. The composite beads could also adsorb dyes like reactive black, Congo red, direct yellow, reactive orange, rhodamine B, crystal violet, and methylene blue (MB). Thermal stability was significantly improved after coating the surface of the 2.5% ZIF beads with a ZnO photocatalyst. After UV irradiation for 5 h, the photocatalytic beads containing 2.59 weight percent of ZnO could decolorize 99% of MB and 90% of RR141 dyes with a degradation rate of 0.6032 h-1 and 0.3198 h-1, respectively. Furthermore, the photocatalytic beads remained effective for at least ten consecutive cycles.

Utilization of Functionalized Metal–Organic Framework Nanoparticle as Targeted Drug Delivery System for Cancer Therapy

Cancer is a multifaceted disease that results from the complex interaction between genetic and environmental factors. Cancer is a mortal disease with the biggest clinical, societal, and economic burden. Research on better methods of the detection, diagnosis, and treatment of cancer is crucial. Recent advancements in material science have led to the development of metal–organic frameworks, also known as MOFs. MOFs have recently been established as promising and adaptable delivery platforms and target vehicles for cancer therapy. These MOFs have been constructed in a fashion that offers them the capability of drug release that is stimuli-responsive. This feature has the potential to be exploited for cancer therapy that is externally led. This review presents an in-depth summary of the research that has been conducted to date in the field of MOF-based nanoplatforms for cancer therapeutics.

Protein-directed synthesis of ZIF-8 functionalized with a polymer as core-shell drug coatings with antibacterial and anti-inflammatory properties

We developed a strategy to use lysozyme (Lys) as a template to produce mesoporous zeolitic imidazolate framework (ZIF-8) structures under physiological conditions. Thereafter, an amphiphilic triblock copolymer, PEG-PPG-PEG, was used to form protective core-shell ZIF-8 nanocomposite coatings to protect the encapsulated drug epigallocatechin-3-gallate (EGCG), to achieve notable antibacterial properties against E. coli, S. aureus and MRSA strains. Moreover, nanocomposites exhibited anti-inflammatory activity by counteracting the secretion of cytokines in THP-1 macrophages.

Implication toward a simple strategy to generate pH tunable FRET-based biosensing

The present contribution depicts a unique approach to generate tunable Förster resonance energy transfer (FRET) emission with variation of pH of the medium. The pH sensitive absorption of Doxorubicin leads to modification of spectral overlap between emission spectra of donor (Pyrazoline) and absorption spectra of acceptor (Doxorubicin) thereby sensing maximum FRET efficiency in an optimum pH (near pK_a of Doxorubicin). This drug molecule exhibits an instantaneous conformation change at a particular pH, which consequences on abrupt ON-and-OFF FRET efficiency. At elevated pH, both the drug molecules exhibit conformational change and form stable fluorescent exciplex, switching off the FRET emission. Confocal fluorescence images of live HepG2 cells imply that the sensor can proficiently go through the cell membrane and can be applied in the controlled delivery of drug to the tumor cell lines.

Metolachlor metal-organic framework nanoparticles for reducing leaching, ecotoxicity and improving bioactivity

BACKGROUND

The adverse effects of pesticides has led to a series of ecological, environmental and public health issues. Amide herbicides are an important agrochemical, yet many are prone to leach and pollute the environment, which limits their further application. In this study, metolachlor (METO) was selected as a model pesticide and a controlled released nanoparticle (NP) system was constructed employing a zeolitic imidazolate framework-8 hybrid inorganic-organic porous material (METO@ZIF-8).

RESULTS

The synthesis parameters of METO@ZIF-8 were optimized, and the loading content of METO@ZIF-8 was maximized by a central composite design of response surface test. The NPs were regular dodecahedron with uniform size (mostly 54.3 nm diameter). METO@ZIF-8 had high specific surface area and good dispersal in water. Moreover, it endowed the active ingredient with a pH-responsive release property. The nanocarrier effectively improved the adsorption capacity of METO in soil and reduce the leaching by 10.3-21.7%. Pot experiments suggested that the control effect of METO@ZIF-8 was 16.6 and 48.4% higher than that of METO emulsifiable concentrate (EC) and METO technical concentration (TC) at the recommended dose. Based on the excellent controlled release profiles, METO@ZIF-8 did not affect corn plant growth and significantly reduced the risk of phytotoxicity induced by METO. METO@ZIF-8 effectively reduced acute toxicity in zebrafish compared with METO EC.

CONCLUSION

This study explored the fabrication of a nanocarrier for improving the efficacy and promoting the environmental safety of leachable amide herbicides. © 2022 Society of Chemical Industry.

Multifunctional ZnO:Gd@ZIF-8 hybrid nanocomposites with tunable luminescent-magnetic performance for potential bioapplication

Novel multifunctional ZnO:Gd@ZIF-8 hybrid inorganic-organic nanocomposites with tunable luminescent-magnetic performance were successfully fabricated using wet chemistry synthesis routes. Physico-chemical characterization including crystal structure, phase compositions, morphology, surface properties, as well as photoluminescent and magnetic characteristics was performed using powder X-ray diffraction (XRD), FT-IR analysis, transmission and scanning electron microscopies (TEM/SEM), N₂ adsorption/desorption, SQUID magnetometer, and photoluminescence spectroscopy. The biological studies of obtained materials, such as cytotoxicity profile and in vitro MRI imaging also investigated for potential use as contrast agents. Results showed that the doping with Gd³⁺ in a broad concentration range and the presence of ZIF-8 layer on ZnO affect the physico-chemical properties of the obtained composites. The obtained porous ZnO:Gd@ZIF-8 composites were highly crystalline with a large surface area. The XRD study indicated the formation of hexagonal wurtzite structure for ZnO and ZnO:Gd³⁺ (1-5 at.%). Luminescent studies showed, that ZnO is an ideal matrix for the incorporation of Gd³⁺ ions in a broad concentration range with efficient green luminescence. The PL intensity reached the maximum up to 5 at.% of Gd³⁺. The zeta potential values indicated the good stability of obtained nanoparticles. Proposed new materials with paramagnetic behavior and outstanding MR imaging capability could be used as potential contrast agents for magnetic resonance imaging.

Fabrications of hybrid Polyurethane-Pd doped ZrO2 smart carriers for self-healing high corrosion protective coatings

The work demonstrates the effective utilization of hybrid Polyurethane - palladium doped zirconium oxide (Pd-ZrO₂) as innovative carriers for corrosion protection coatings on steel materials. ZrO₂ and Pd-ZrO₂ nanoparticles were successfully synthesized using Photodeposition followed by the hydrothermal synthesis method. The synthesized nanoparticles were then incorporated into the polyurethane matrix and characterized using Fourier-transform infrared spectroscopy and scanning electron microscopy (SEM). The FTIR and SEM confirm the presence of ZrO₂ and Pd-ZrO₂ nanoparticles and their morphologies in polyurethane composites material. The thermogravimetric analysis (TGA) results indicated that the polyurethane matrix remained stable up to 250 °C. At 800 °C, >50% of residues are observed for Pd-ZrO₂ - polyurethane in the TGA analysis, which confirms that the primer and nanoparticles addition enhances the thermal stability of the composite. The water contact angle measurement explains the hydrophobic behavior of nanocomposite modified coatings on a mild steel substrate. It indicates that Pd-ZrO₂ and primer significantly increase the hydrophobicity of polyurethane. The major advantages of developing water-repellent or hydrophobic surfaces open up a world of possibilities for metals and alloys in terms of corrosion prevention. Electrochemical impedance spectroscopy (EIS) and a salt spray test were used to determine the anti-corrosion behavior of the prepared polymer nanocomposites. The polymer nanocomposite coatings have better anti-corrosive capabilities when compared to pure polyurethane. The corrosion protection efficiency increased from 76.63% to 97.57% upon incorporating 2 wt % of Pd-ZrO₂ in the polyurethane matrix. The results confirmed that the modifications on the polyurethane enhanced the hydrophobicity and anti-corrosion properties of the polymer nanocomposite coatings.

Dual Stimuli-Responsive Multifunctional Silicon Nanocarriers for Specifically Targeting Mitochondria in Human Cancer Cells

Specific targeting, selective stimuli-responsiveness, and controlled release of anticancer agents are requested for high therapeutic efficiency with a minimal adverse effect. Herein, we report the sophisticated synthesis and functionalization of fluorescent mesoporous silicon (FMPSi) nanoparticles decorated with graphene oxide (GO) nanosheets. GO-wrapped FMPSi (FMPSi@GO) was loaded with a cisplatin (Cis) anticancer agent, and Cis-loaded FMPSi@GO (FMPSi-Cis@GO) exhibited the dual stimuli (pH and NIR)-responsiveness of controlled drug release, i.e., the drug release rate was distinctly enhanced at acidic pH 5.5 than at neutral pH 7.0 and further enhanced under NIR irradiation at acidic pH condition. Notably, dequalinium-conjugated FMPSi-Cis@GO (FMPSi-Cis@GO@DQA) demonstrated an excellent specificity for mitochondrial targeting in cancer cells without noticeable toxicity to normal human cells. Our novel silicon nanocarriers demonstrated not only stimuli (pH and NIR)-responsive controlled drug release, but also selective accumulation in the mitochondria of cancer cells and destroying them.

Polyacrylic Acid Nanoplatforms: Antimicrobial, Tissue Engineering, and Cancer Theranostic Applications

Polyacrylic acid (PAA) is a non-toxic, biocompatible, and biodegradable polymer that gained lots of interest in recent years. PAA nano-derivatives can be obtained by chemical modification of carboxyl groups with superior chemical properties in comparison to unmodified PAA. For example, nano-particles produced from PAA derivatives can be used to deliver drugs due to their stability and biocompatibility. PAA and its nanoconjugates could also be regarded as stimuli-responsive platforms that make them ideal for drug delivery and antimicrobial applications. These properties make PAA a good candidate for conventional and novel drug carrier systems. Here, we started with synthesis approaches, structure characteristics, and other architectures of PAA nanoplatforms. Then, different conjugations of PAA/nanostructures and their potential in various fields of nanomedicine such as antimicrobial, anticancer, imaging, biosensor, and tissue engineering were discussed. Finally, biocompatibility and challenges of PAA nanoplatforms were highlighted. This review will provide fundamental knowledge and current information connected to the PAA nanoplatforms and their applications in biological fields for a broad audience of researchers, engineers, and newcomers. In this light, PAA nanoplatforms could have great potential for the research and development of new nano vaccines and nano drugs in the future.

Experimental and computational investigation of a green Knoevenagel condensation catalyzed by zeolitic imidazolate framework-8

ZIF-8 is a highly porous, stable, and abundant surface area material that can be used as an environmentally friendly catalyst for Knoevenagel condensations. The effects of the ratio of the reactants (benzaldehyde (BA):ethyl cyanoacetate (ECA)), reaction temperature, and catalyst concentration were systematically investigated using a ZIF-8 catalyst and water as the solvent. ZIF-8 (3-5 wt%) showed excellent catalytic performance with an almost complete conversion of BA in less than 6 h with a BA:ECA molar ratio of 1:2 at different temperatures. At 60 °C, the BA conversion rate and product selectivity of the reaction reached their highest values after 4 h with a BA:ECA molar ratio of 1:1. When employing 5.0 wt% ZIF-8, almost complete BA conversion was achieved after 3 h at room temperature. ZIF-8 also demonstrated good recyclability with almost no change in its catalytic activity over five cycles. The proposed reaction mechanism is based on the catalytic activity of the basic N sites on the surface of ZIF-8, and is supported by density functional theory calculations. The present approach provides a promising strategy for the construction of simple and environmentally friendly ZIF-8 catalysts.

Flexible and high-sensitivity sensor based on Ti3C2-MoS2 MXene composite for the detection of toxic gases

It is vital to have high sensitivity in gas sensors to allow the exact detection of dangerous gases in the air and at room temperature. In this study, we used 2D MXenes and MoS₂ materials to create a Ti₃C₂-MoS₂ composite with high metallic conductivity and a wholly functionalized surface for a significant signal. At room temperature, the Ti₃C₂-MoS₂ composite demonstrated clear signals, cyclic response curves to NO₂ gas, and gas concentration-dependent. The sensitivities of the standard Ti₃C₂-MoS₂ (TM_2) composite (20 wt% MoS₂) rose dramatically to 35.8%, 63.4%, and 72.5% when increasing NO₂ concentrations to 10 ppm, 50 ppm, and 100 ppm, respectively. In addition, the composite showed reaction signals to additional hazardous gases, such as ammonia and methane. Our findings suggest that highly functionalized metallic sensing channels could be used to construct multigas-detecting sensors that are very sensitive in air and at room temperature.

Remote sensing of wetland evolution in predicting shallow groundwater arsenic distribution in two typical inland basins

A large number of studies have shown that the existence of wetlands may influence arsenic concentrations in adjacent shallow groundwater. However, little is known about the linkage between wetland evolution and arsenic enrichment in shallow groundwater. This study investigated wetland evolutions from 1973 to 2015 in two arid-semiarid inland basins along the Yellow River catchment (i.e., the Yinchuan Basin and the Hetao Basin) based on remote sensing data, and their association with arsenic distributions based on arsenic concentrations of 244 and 570 shallow groundwater samples, respectively. The long-term Landsat images reveal that the covering area of wetlands exhibited increasing trends in both the Yinchuan Basin and the Hetao Basin. Wetlands in the Yinchuan Basin and the Yellow River water-irrigation area in the Hetao Basin varied with precipitation before 2000, but exhibited increasing trends because of wetland restoration policies since 2000. Wetlands in groundwater-irrigation area in the Hetao Basin decreased due to increasing exploitation of shallow groundwater. Wetlands with long existence time were mainly distributed along the Yellow River and drainage channels and in large lakes in the northern Yinchuan Basin and the Hetao Basin, where high‑arsenic (>10 μg/L) groundwater occurred. The probability of high‑arsenic groundwater distribution increased with the proportion of wetland existence time to the entire studied period (42 years), which can be best explained by a BiDoseResp growth curve. Longer existence of wetlands may cause greater probability of high‑arsenic groundwater. This was likely related to long-term introduction of biodegradable organic matter into shallow aquifers and thereafter enhancement of arsenic mobility and/or arsenic being released beneath wetlands and transported into shallow aquifers under continuing wetland water recharge. We therefore suggest that mapping wetland evolutions could probably serve as a good indicator for predicting high arsenic groundwater distributions in shallow aquifers.

Novel α-Mangostin Derivatives from Mangosteen (Garcinia mangostana L.) Peel Extract with Antioxidant and Anticancer Potential

The mangosteen peels contain biologically active compounds, with antioxidant and anticancer properties. Among these isolated phytochemicals, α-mangostin is one of the most powerful natural antioxidants and anticancer compounds. This study focused on synthesizing novel α-mangostin (α-MG) derivatives at positions of C-3 and C-6 from extracted α-MG of mangosteen peels and investigating antioxidant and anticancer activities. The structures of the synthesized compounds were determined by using MS, 1H-NMR, 13C-NMR, and HPLC. The analysis of the interaction between structure and bioactivity showed that phenol groups on C-3 and C-6 positions play a crucial role in antiproliferative activity to boost both anticancer efficacy and drug-like properties. The antioxidant activity of α-MG and its derivatives were investigated by the DPPH method. Among α-MG derivatives, 1-hydroxy-7-methoxy-2,8-bis(3-methylbut-2-en-1-yl)-9-oxo-9H-xanthene-3,6-diyl bis(2-bromobenzoate) (compound 4) exhibited significant antioxidant property. The in vitro cytotoxicity against various cancer cell lines (HeLa, MCF-7, NCI–H460, and HepG2) was evaluated by the standard sulforhodamine B assay. The anticancer activities (HeLa, MCF-7, NCI–H460, and HepG2) of compound 4 are five to six times higher than those of α-MG and other derivatives. The acetylation at C-3 and C-6 of α-MG by halogen of benzoyl greatly improved cancer cell toxicity. Our results provide new opportunities for further explorations of α-MG derivatives for antioxidant property and promise as drugs in cancer therapy.