Search

Constructing three-dimensional (3D) foam-like structure in magnetic metal/carbon composites is regarded as a promising pathway to reinforce their electromagnetic (EM) functions. Herein, a nitrate-assisted polymer-bubbling strategy is reported for the synthesis of Co/carbon foams, which is simply accomplished by direct pyrolyzing the mixture of polyvinylpyrrolidone (PVP) and cobalt nitrate hexahydrate (Co(NO3)2∙6H2O). Co(NO3)2∙6H2O not only plays as the source of Co nanoparticles, but also accounts for the formation of 3D microstructure through releasing gas. By manipulating the weight ratio of Co(NO3)2∙6H2O to PVP, the chemical composition, microstructure, and EM properties of these composites can be easily regulated. When the weight ratio reaches 1.5, the resultant composite displays good microwave absorption performance, whose reflection loss intensity and effective absorption bandwidth are superior to those of many common Co/C composites. EM analysis reveals that such architecture is greatly helpful to establish cross-linked conductive networks in the wax matrix, resulting in powerful dielectric loss under low absorber loading. Meanwhile, 3D microstructure is also beneficial for multiple reflections that equal to extend the transmission path of incident EM waves. Simple synthesis strategy and desirable properties of these magnetic carbon foams may render them as the low-cost substitute of 3D graphene for the application against EM pollution.

Background: In recent years, it is reported that non-invasive brain stimulation [including transcranial direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS)] could improve lower limb function in patients after stroke. However, some studies showed no effect. In the present study, we aimed to make a meta-analysis to assess effect of non-invasive brain stimulation on lower limb function in patients after stroke. Methods: Studies exploring the effect of tDCS or rTMS on lower limb function in patients after stroke were searched on the PubMed, Web of Science, EMBASE, Medline, Google Scholar before March 2021. Meta-analysis was made to summarize results of these studies. Results: The present study showed significantly better walking speed, mobility and muscle strength increase effect in tDCS group compared to sham tDCS group [walking speed: standard mean difference (SMD) = 1.14, 95% CI = 0.48 to 1.80, I2 = 74.0%, p value for Q test < 0.001; mobility: SMD = 0.79, 95% CI = 0.21 to 1.36, I2 = 53.8%, p value for Q test = 0.043; muscle strength: SMD = 2.79, 95% CI = 0.61 to 4.98, I2 = 93.9%, p value for Q test < 0.001]. In addition, meta-analysis showed significantly better walking speed, balance and motor function increase effect in rTMS group compared to sham rTMS group [walking speed: SMD = 3.31, 95% CI = 1.38 to 5.24, I2 = 92.1%, p value for Q test < 0.001; balance: SMD = 3.54, 95% CI = 1.45 to 5.63, I2 = 95.4%, p value for Q test < 0.001; motor function: SMD = 1.65, 95% CI = 0.53 to 2.76, I2 = 90.3%, p value for Q test < 0.001]. Conclusions: This meta-analysis suggested that non-invasive brain stimulation improved lower limb function in patients after stroke. More large scale, blinded RCTs were necessary to confirm the effect of rTMS and tDCS on lower limb function in patients after stroke.

Metal-organic frameworks (MOFs) transformation is evolving into an attractive strategy for the synthesis of functional carbon-based materials in different fields. However, this method is usually inapplicable to hierarchical carbon-based composites, because high-temperature pyrolysis easily accounts for microstructure collapse. Herein, with NiCo Prussian blue analog (PBA) microcubes as the precursor, we successfully harvest hollow NiCo@C microboxes through alkaline etching and phenolic resin (PR) reinforcement. PR modification not only stabilizes the microstructure during high-temperature pyrolysis, but also realizes the regulation of chemical composition simultaneously. The stability of microstructure essentially benefits from the fact that PR-derived carbon layer suppresses the agglomeration of NiCo nanoparticles effectively. Electromagnetic (EM) analysis suggests that hollow microstructure is very helpful to enhance dielectric loss, stimulate multiple reflection and scattering of EM waves, and realize good impedance matching. When the thickness of PR layer is optimized, the resultant hollow NiCo@C microboxes will possess excellent microwave absorption property, whose minimum reflection loss value can be as strong as −68.4 dB at 13.4 GHz and qualified bandwidth can cover 14.1 GHz (3.9–18.0 GHz) by integrating the absorber thickness from 1.00 to 5.00 mm. Such a performance promises hollow NiCo@C microboxes a bright prospect as potential candidates against EM pollution.

Microwave absorbing materials (MAMs), which have been highly developed in the past two decades, are being regarded as a kind of functional materials to combat electromagnetic (EM) pollution, because they can provide sustainable energy conversion rather than simple reflection of incident EM waves. Although traditional magnetic materials can dissipate EM energy effectively, they always suffer from some intrinsic drawbacks, such as high density, easy corrosion, and skin effect, which make them unpopular in many practical applications. Therefore, the rational design of pure dielectric system without any magnetic components is becoming a new frontier topic for MAMs. Among various candidates, carbon-based dielectric system almost dominates the development of non-magnetic MAMs. This review presents a comprehensive introduction on the recent advances of carbon-based dielectric system composed of carbon materials and other dielectric components, including metal oxides/carbon, metal sulfides/carbon, conductive polymers/carbon, carbides/carbon, carbon/carbon, and various ternary carbon-based dielectric composites. Thanks to the synergistic effects between different components and the elaborate microstructure design, these carbon-based dielectric composites can produce superior microwave absorption performance to traditional magnetic materials. Moreover, the challenges and prospects are also proposed to indicate some new insights for the further research of carbon-based dielectric system.

Carbon/carbon composites are becoming promising functional materials with wide applications in many fields. Although they are always considered as qualified candidates for lightweight and durable microwave absorbing materials (MAMs), their electromagnetic (EM) performance still suffers from the imbalance between characteristic impedance and loss capability. With carbon nanotubes (CNTs) as the scaffold, we herein direct the in situ growth of ZIF-8 nanocrystals on their surface and then convert the intermediate into porous carbon nanoparticles/CNTs (PCNs/CNTs) composites with a unique core-sheath structure. Interestingly, the combination of PCNs and CNTs create a positive synergistic effect on the overall EM properties. On the one hand, graphitic CNTs can maintain their powerful intrinsic loss toward incident EM waves, and on the other hand, amorphous PCNs closely anchored on CNTs can regulate the impedance matching effectively and bring sufficient interfacial polarization that is favorable for the consumption of EM energy. By manipulating the relative contents of PCNs and CNTs, the optimal PCNs/CNTs composite produces excellent EM absorption performance, whose strongest reflection loss can reach up to −71.5 dB with the absorber thickness of only 1.1 mm and the integrated effective absorption bandwidth is as broad as 15.1 GHz. Such a performance is superior to those of most of the reported carbon/carbon composites. These results indicate that a precise design of the configuration of carbon/carbon composites will be a valid way to develop novel and high-performance MAMs.

Hierarchical microstructures are playing important roles in the design and fabrication of high-performance microwave absorbing materials (MAMs) owing to their unique advantages. In this work, a series of special “double-hierarchical” N-doped carbon nanotubes wrapping waxberry-like Ni@C microspheres (NC@NCNTs) have been rationally designed and successfully fabricated by two-step pyrolysis processes, where the loading amount of NCNTs on the waxberry-like Ni@C microspheres can be easily modulated by changing the dosage of melamine. Benefiting from sufficient attenuation ability and good impedance matching, NC@NCNTs-2, whose relative carbon content is 51.1 wt%, exhibits the best reflection loss (RL) characteristics among this series of composites, including the minimum RL intensity of −41.5 dB and an effective absorption bandwidth of 5.2 GHz with an absorber thickness of only 1.7 mm. This performance is superior to that of many homologous Ni/C composites reported previously. The investigation on EM properties indicates that the unique “double-hierarchical” architecture of NC@NCNTs can not only create stronger dipole orientation and interfacial polarization relaxation, but can also result in higher conductive loss as well as extra multiple reflection effects for incident electromagnetic waves. We believe that these results will provide some inspirations and pathways for the production of high-performance MAMs with senior microstructures in the future.

Rational optimization on chemical composition and microstructure is a hot topic for magnetic carbon-based composites to overcome their challenges in microwave absorption. In this study, we demonstrate the synthesis of uniform Co/C microspheres with tunable chemical composition through a solvothermal reaction followed by high-temperature pyrolysis. It is found that this simple strategy greatly benefits from the dual functions of glucose. On one hand, glucose is the source of gluconate as the organic ligand to complex with Co ions and produce uniform Co-gluconate microspheres, and on the other hand, glucose can be converted into carbon nanoparticles and accommodated in Co-gluconate microspheres. The final Co/C microspheres display quite different electromagnetic properties as compared with pure metal Co particles. The presence of carbon component and high dispersion of Co nanoparticles induce positive reinforcements in both dielectric loss and magnetic loss. As a result, these Co/C microspheres can produce better microwave absorption performance, especially for Co/C-1.0 (the weight ratio of glucose to cobalt nitrate is 1.0), whose strong reflection loss and wideband response are also superior to those similar composites in previous reports. It is believable that this work may provide a new strategy for magnetic carbon-based composites with desirable microstructure and chemical composition.

Epoxy resin (EP)-based composites have been widely used as a new type of insulating material in ultra-high voltage direct current transmission network. In this work, we prepare a series of TiO2-loa...

Microstructure is playing a more and more important role in upgrading the performance of microwave absorption materials (MAMs) nowadays. Herein, we demonstrate the successful synthesis of multi-chamber carbon microspheres (MCCMs) with abundant interior cavities. The reflection loss (RL) characteristics of MCCMs and the effect of microstructure on electromagnetic properties have been discussed thoroughly. It is found that compared with the solid carbon microspheres, MCCMs possess reinforced dielectric loss and attenuation ability towards incident electromagnetic waves, and in contrast to hollow carbon microspheres, the unique multi-chamber architecture endows MCCMs with better impedance matching characteristic. More importantly, it is proved that the consolidated multiple reflection effect originated from multi-chamber microstructure can contribute to reinforced attenuation ability and optimized impedance matching characteristic simultaneously. In consequence, MCCMs exhibit enhanced microwave absorption properties, including the minimum RL intensity of −28.5 dB at 10.2 GHz with the thickness of 2.0 mm and the widest effective absorption bandwidth of 5.7 GHz with the thickness of 1.8 mm. It is believed that these results will provide some practical significance for high-performance MAMs based on carbon-related materials with profitable microstructure.

In vitro fermentation was used to evaluate the possible effects of intervention with Lactobacillus paracasei N1115 (LP N1115) on gut microbiota and metabolite shortchain fatty acids (SCFAs) in pregnant women with constipation and diarrhea. Feces were collected from pregnant women and fermented by YCFA medium to profile the changes in the gut microbiota before and after intervention with LP N1115 using 16SrRNA sequencing. At the same time, the changes in several specific bacteria were detected using quantitative real-time PCR (qPCR) and the SCFAs in fermentation were detected using gas chromatography (GC) for each subject to determine the effect of the intervention. In vitro intervention with LP N1115 significantly increased the relative abundances of Lactobacillus, Faecalibacterium prausnitzii, and Bifidobacterium in constipated pregnant women and reduced the contents of acetic acid, propanoic acid. Moreover, 16S rRNA gene analysis showed that LP N1115 also reduced the relative abundance of Clostridium_XI. The results of this study suggest that LP N1115 might increase the content of beneficial bacteria and reduce the relative abundance of pathogenic bacteria, which might be beneficial to gut health in pregnant women.

Highlights This review introduces recent advances to optimize electromagnetic properties of metal-organic frameworks (MOFs)-derived magnetic carbon-based composites through rational microstructure design and composition optimization in detail.The challenges and outlooks in MOFs-derived magnetic carbon-based microwave absorbers are also proposed and analyzed, including low-frequency absorption, diversified MOFs precursors, structure-activity relationships, environmental tolerance., Magnetic carbon-based composites are the most attractive candidates for electromagnetic (EM) absorption because they can terminate the propagation of surplus EM waves in space by interacting with both electric and magnetic branches. Metal-organic frameworks (MOFs) have demonstrated their great potential as sacrificing precursors of magnetic metals/carbon composites, because they provide a good platform to achieve high dispersion of magnetic nanoparticles in carbon matrix. Nevertheless, the chemical composition and microstructure of these composites are always highly dependent on their precursors and cannot promise an optimal EM state favorable for EM absorption, which more or less discount the superiority of MOFs-derived strategy. It is hence of great importance to develop some accompanied methods that can regulate EM properties of MOFs-derived magnetic carbon-based composites effectively. This review comprehensively introduces recent advancements on EM absorption enhancement in MOFs-derived magnetic carbon-based composites and some available strategies therein. In addition, some challenges and prospects are also proposed to indicate the pending issues on performance breakthrough and mechanism exploration in the related field.

To quantify viable probiotic Lacticaseibacillus paracasei (L. paracasei) in fermented milk accurately and quickly, propidium monoazide combined with quantitative loop-mediated isothermal amplification (PMA-qLAMP) was applied. The optimal PMA treatment conditions for treating a L. paracasei suspension were determined using an orthogonal test to eliminate the DNA amplification of 108 CFU/mL of dead L. paracasei. Primers were designed based on the species-specific gyrB gene of L. paracasei. A phylogenetic tree based on the gyrB gene showed that L. paracasei clustered on the same branch with 91% support. Compared with the 16 strains commonly found in fermented milk, three strains of L. paracasei showed positive PMA-qLAMP results, and the melting temperature was approximately 82.4°C. There was a linear relationship (R2 = 0.9983) between the Ct values and the logarithm of the concentration of viable bacteria. The PMA-qLAMP detection limit for the L. paracasei artificially added to fermented milk was 7.3 × 102 CFU/mL. There was no significant difference between the logarithm values of the concentration of viable L. paracasei of 50 fermented milk samples within shelf life using the PMA-qLAMP and plate count methods (P > 0.01). PMA-qLAMP is specific and accurate for obtaining reliable results faster than when using plate counts.

Transition metal carbides/carbon composites are appearing as attractive microwave absorption materials (MAMs) due to their positive synergistic effects as well as good chemical stability. In this study, we trigger the polymerization of pyrrole monomer in the presence of phosphomolybdic acid (PMo12) at room temperature, and then convert the homogeneous PMo12/polypyrrole (PMo12/PPy) nanospheres into Mo2C@C nanospheres under high-temperature inert atmosphere. The carbonization of PPy conjugated chains also induces the in situ formation of Mo2C nanoparticles, resulting in a unique pomegranate-like microstructure. The pyrolysis temperature plays important roles in determining the size and crystalline phase of Mo2C nanoparticles, chemical composition, and the relative graphitization degree of carbon framework. As a dual dielectric system, conductivity loss is primarily responsible for the consumption of electromagnetic energy in Mo2C@C nanospheres, and dipole orientation polarization and interfacial polarization provide auxiliary contribution in this process. It is found that high pyrolysis temperature favors powerful dielectric loss capability. However, the desirable microwave absorption is established in the composite from moderate pyrolysis temperature (700 °C), where the strongest reflection loss reaches −48.0 dB at 12.5 GHz and the integrated qualified bandwidth covers the frequency range of 3.5–18.0 GHz. This is because moderate pyrolysis temperature endows Mo2C@C nanospheres with proper attenuation capability and matched characteristic impedance. In view of its excellent microwave absorption performance and simple preparation method, such Mo2C@C nanospheres with pomegranate-like heterostructure will be a kind of promising candidate for lightweight and broadband MAMs in the future.

Binary dielectric composites are viewed as a kind of promising candidate for conventional magnetic materials in the field of microwave absorption. Herein, we demonstrate the successful fabrication ...

Rational manipulation on chemical composition and microstructure is evolving as a powerful approach to reinforce the electromagnetic (EM) functions of magnetic carbon-based composites. With FeCo Prussian blue analogs (FeCo PBAs) as the nucleation sites, we conduct the polymerization of dopamine (DA) on their surface and then convert the precursor into desirable FeCo alloy/carbon composites. PDA coating is greatly helpful to suppress the microstructure collapse of FeCo PBAs during high-temperature pyrolysis, resulting in a unique hierarchical configuration of core-shell FeCo@C nanoparticles encapsulated in PDA-derived carbon nanocages. The formation of carbon nanocages not only adjusts the relative carbon content, but also affects EM properties of these composites. In particular, the dielectric loss can be significantly enhanced, which further accounts for an improvement in overall attenuation ability toward incident EM waves. When the weight ratio of DA to FeCo PBAs reaches 0.75, the obtained composite will exhibit excellent microwave absorption performance thanks to its decent attenuation ability and matched characteristic impedance. The strongest reflection loss intensity is located at −67.8 dB at 15.8 GHz, and the effective bandwidth covers 11.0–16.3 GHz with the thickness of 2.00 mm. The advantages in microstructure are also established by parallel comparison with a disordered counterpart.

The rational design of the microstructure of magnetic carbon-based composites has become a popular strategy to enhance their microwave absorption properties. Herein, with Ni-containing metal–organic framework as the self-sacrificing precursor, we have successfully prepared waxberry-like Ni@C microspheres as novel microwave absorbing materials, which artfully integrated the advantages of core–shell configuration and hierarchical architecture. The effects of the pyrolysis temperature on the microstruture, carbon content, relative graphitization degree, magnetic properties, and electromagnetic parameters were carefully investigated. The composite that was pyrolyzed at 700 °C (Ni@C-700) exhibited desirable microwave absorption performance, including a strong reflection loss intensity of −73.2 dB and a broad qualified bandwidth of 4.8 GHz with an applied thickness of 1.8 mm. The electromagnetic analysis revealed that such good performance of Ni@C-700 was benefited from both the well-matched impedance and decent attenuation ability. The superiority of this unique microstruture was also validated by comparing it with some homologous composites and isolated core–shell Ni@C nanoparticles. It is believed that these results may provide a new pathway to promote the electromagnetic applications of conventional magnetic carbon-based composites by optimizing their microstructure.

Binary dielectric composites are viewed as a kind of promising candidate for conventional magnetic materials in the field of microwave absorption. Herein, we demonstrate the successful fabrication of core-shell BaTiO

A drug delivery nanocarrier was constructed with upconverting nanoparticles as the core and photosensitizer‐doped mesoporous silica as the shell. A reactive oxygen species (ROS)‐cleavable thioketal linker was grafted as a “gate” to ensure targeted release. Upon near‐IR irradiation, the visible light emission excites the photosensitizer to generate ROS, which makes the “gate” open and releases the drug.

Transition metal carbides with good chemical stability and moderate dielectric constants are becoming popular electromagnetic (EM) absorption materials. In this work, Mo2C/Co/C composites, a ternary loss system (conductivity loss, polarization loss, and magnetic loss) for EM absorption, have been successfully fabricated by rationally regulating the growth of ZIF-67 on the surface of MoO3 nanorods and subsequent pyrolysis process. The chemical compositions of Mo2C/Co/C composites indeed play a dominant role in tailoring their EM functions. It is revealed that conductivity loss, polarization loss, and magnetic loss are together responsible for the attenuation of EM energy. Although the involvement of Mo2C nanoparticles weakens magnetic loss capability to some extent, there will be a positive reinforcement in conductivity loss through the synergistic effects among different components. In addition, Mo2C nanoparticles can further provide considerable dipole orientation polarization and interfacial polarization. Among these ternary composite, MCC-50 with 30.9% of carbon, 53.6% of Mo2C, and 15.5% of Co, exhibits the best EM absorption performance, whose reflection loss intensity and qualified response bandwidth are superior to those of most carbide-based composites in previous studies. These results suggest that the rational integration of components with different loss mechanisms will be an effective pathway to enhance EM absorption.

We report the facile synthesis of freestanding MnO2 nanoflakes/porous carbon nanofibers (MnO2/PCNFs) for high performance flexible supercapacitor electrodes. PCNFs are firstly synthesized via a electrospinning method using phenol-formaldehyde resin as the carbon precursor with tetraethyl orthosilicate and triblock copolymer Pluronic P123 as porous and soft templates, respectively. MnO2 nanoflakes are then in-situ deposited on PCNFs based on the self-limiting reaction between KMnO4 and carbon. The obtained MnO2/PCNF hybrid shows a porous structure with ultra-high specific surface area of 1814 m2 g−1, providing numerous electroactive sites to accommodate more charges. As a result, the MnO2/PCNF hybrid electrode exhibits extremely high specific capacitance (520 F g−1 at 0.5 A g−1) and superior cycling stability (92.3% retention after 4000 cycles) in a 6 M KOH aqueous solution. Such excellent electrochemical behavior may render this hybrid a promising candidate for flexible, freestanding and high-performance supercapacitor electrodes.

A pH-sensitive nanocarrier has been developed for the controlled intracellular release of drugs. The nanocarrier, which is approximately 75 nm in size, is composed of a gold nanorod (GNR) core and mesoporous silica shell (GNR@mSiO2) and shows good stability and biocompatibility, and excellent photothermal effects. Doxorubicin hydrochloride (DOX), a typical anticancer drug, was adopted as the model drug, and was connected to the mesoporous silica through Schiff base bonding. The drug-loading nanocarriers (GNR@mSiO2-DOX) exhibit enhanced drug release under acidic conditions owing to the sensitive Schiff base linker, whereas at high pH values low levels of premature release can be detected. The sensitive release mechanism was further investigated by monitoring the zeta potential before and after drug release. HeLa cells were used as typical cancer cells, and detailed cell experiments were carried out to confirm the good biocompatibility, rapid uptake, and acid-enhanced drug delivery of GNR@mSiO2-DOX. Moreover, the synergistic effect of chemotherapy and hyperthermia (photothermal effect from GNRs) of the nanocarrier can be expected to lead to improved therapy effects on cancer treatment.

Fe3O4@mSiO2 (magnetic Fe3O4 core coated by a mesoporous silica shell) nanoparticles were successfully synthesized as a carrier. The anti-cancer drug doxorubicin (DOX) and chlorambucil (Chl) were used as the model cargo. After the drug-loading, a sodium hyaluronic acid (HA) cross-linked gel was adopted to coat the outside of the Fe3O4@mSiO2 nanoparticles as a layer (named as drug–Fe3O4@mSiO2–HA) to prevent drug pervasion. The detailed release kinetics were investigated, revealing the sensitive release triggered by hyaluronidase (HAase), a major enzyme which is rich in the tumor microenvironment, which can degrade the HA shell to induce the enzyme sensitive drug release. Moreover, there are some HA receptors in many tumor areas, associating with magnetic targets to further ensure the specific targeted drug delivery. With these improved performances, these smart multifunctional nanocomposites are expected to possess potential applications in the biopharmaceutical for cancer therapy.

Multifunctional nanocarriers based on the magnetic Fe3O4 nanoparticle core and bis-(3-carboxy-4-hydroxy phenyl) disulfide (R–S–S–R1) modified mesoporous silica shell (Fe3O4@mSiO2@R–S–S–R1) were synthesized for cancer treatment through passive targeting and enzyme-sensitive drug release. Anti-cancer drug doxorubicin (DOX) was used as the model cargo to reveal the release behavior of the system. The drug loading system (DOX–Fe3O4@mSiO2@R–S–S–R1) retains the drug until it reaches the tumor tissue where glutathione reductase (GSH) can degrade the disulfide bonds and release the drug. Furthermore, the grafting amount of R–S–S–R1 can be used to adjust the release performance. All the release behaviors fit the Higuchi model very well and the release kinetics are predominated by disulfide bond degradation and mesoporous structure. With good bioactivity and targeted release performance, the system could play an important role in the development of intracellular delivery nanodevices for cancer therapy.

A novel near infrared (NIR)-triggered anticancer drug delivery system has been successfully constructed. Firstly, upconversion nanoparticles (UCNPs, NaYF4:Tm,Yb@NaYF4) were synthesized as a core and mesoporous silica (mSiO2) as a shell to assemble the core–shell nanostructure (UCNP@mSiO2) as the host. Supramolecular nanovalves based on α-cyclodextrin (α-CD) torus encircling a pimelic acid thread and being held in place by a cleavable stopper (nitrobenzyl alcohol) were used as nanoscopic caps to block the pore and inhibit drug diffusion. Upon irradiation with a 980 nm laser on the nanocomposites, the emitted ultraviolet light (UV, 360 nm) photocleaved the o-nitrobenzyl (ONB) photolabile group, causing these α-CD caps to dissociate from the stalk and release the drug. The “Ladder” pulsatile release-profiles, regulated by varying the intensity and time duration of NIR irradiation, further reveal the light-triggered release performance. In addition, without NIR irradiation, few immaturities ensure the high pharmacological efficacy. Moreover, the elaborate cell experiments, by using HeLa as model cancer cells, were also carried out to reveal the good biocompatibility, fast uptake and NIR light-sensitive toxicity. Therefore, the novel NIR light-triggered drug delivery system displays great potential for cancer therapy.

A multifunctional nanocomposite has been successfully prepared for pH-responsive and magnetic-targeting drug delivery. First, Fe3O4@mesoporous silic (mSiO2) core–shell nanoparticles were synthesized as the nanocapsules. Doxorubicin hydrochloride was adopted as the model drug; after drug loading, gold nanoparticles (5 nm) were connected to block the mesopore through the hydrazone linkage. The hydrazone bond, a typical acid-sensitive bond, could undergo hydrolysis in an acidic environment to induce the release of the capping agent, so that the multifunctional nanocomposite revealed acid-enhanced release performance. What's more, before reaching acid conditions, little premature release was found to take place. Cell experiments were also carried out to reveal the good biocompatibility, fast uptake, and improved toxicity toward HeLa cells. Thus, in association with the magnetic target, the multifunctional nanocomposite shows the potential application for some low-pH tissue-targeted therapy, such as for inflammation and tumors.

With well bioactive and nontoxic, hydroxyapatite (HAp) was employed to seal the nanopores of mesoporous silica (MCM-41) to realize the pH-responsive controlled release. First, MCM-41 was modified with cationic polymer, poly-(diallyldimethylammoniumchloride) (PA). And after the addition of Ca2+/PO4 3−, HAp precipitation can take place based on the cationic sites derived from PA. It is a simple and effective way to obtain HAp coating MCM-41 system (MHAs). The structure of the system was characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope, N2 adsorption–desorption and so on. Metformin hydrochloride was used as the model drug, and the drug release performance and the release kinetics of the system were investigated in detail. Because of the degradation of HAp under acid condition, the drug loading MHAs showed a well pH-sensitive controlled release behavior. From above investigation, MHAs is a promising platform to construct a pH-responsive controlled drug delivery system, especially for some low pH tissues, such as inflammatory and tumor.

A controlled release system with pH-responsive ability has been presented. Mesoporous bioglass (MBG) was used as the drug carrier and a spontaneous mineralization method was adopted to cap the pores of the carrier with hydroxyapatite (HAp) and to restrict the drug release. It is a simple and green method to realize the ingenious pH-sensitive controlled release. The model drug, metformin hydrochloride (MH), was loaded simultaneously with the mineralization process. Due to the degradation of HAp at acid environments, the system shows well pH-sensitive drug release ability. The release kinetics can be easily adjusted by the mineralization time and the ion concentration of media. The system is recommended as a promising candidate as a pH-sensitive vehicle for drug controlled release to low pH tissues, such as inflammatory sites and tumors.

A simple and green method to fabricate an ingenious enzyme-responsive drug controlled release system was presented. Mesoporous silica material (mSiO2) 100 nm in size was used as the host, and Konjac oligosaccharide (KOGC) was employed to seal the nanopores of mSiO2 to inhibit the drug release. Rhodamine B was used as the model cargo to reveal the release behavior of the system. The KOGC-modified mSiO2 (mSiO2@KOGC) retains the drug until it reaches the colonic environment where bacteria secrete enzymes (β-mannanase) can degrade KOGC and make drug release. The amount of KOGC and enzyme can be used to adjust the release performance. And all the release behaviors fit the two-step Higuchi model, which predominate by KOGC degradation and mesoporous structure, respectively. With well bioactivity and selectivity, the system has potential application as an oral medicine carrier for treating intestinal disease.

Monodispersed porous ZnO nanospheres with diameters about 400–600 nm were successfully fabricated by a facile and effective cationic surfactant assisted selective etching strategy. The as-synthesized ZnO materials were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope and N2 adsorption–desorption. These samples were used as the gas sensor, showing the high, stable and fast response to acetone, revealing the potential application as gas sensor to detect acetone. In addition, the photocatalytic degradation property of the porous ZnO nanospheres for methyl orange (MO) under UV irradiation was investigated. The degradation efficiency of MO reaches 96 % of the porous ZnO samples after 50 min of UV-light irradiation.

A novel pH-sensitive drug release system has been synthesised by functional mesoporous silica materials. SBA-15, calcium modified SBA-15 (Ca-SBA-15) and phosphate modified SBA-15 (PO4-SBA-15) were synthesised using solvent evaporation method. It is a simple and feasible way to prepare the doping mesoporous silica materials. They show the large surface are, high pore volume and uniform pore size. Metformin hydrochloride was used as the model drug, and the control release behaviour was investigated. The functional mesoporous silica materials show the pH sensitive drug release behaviour because of the adjustable interaction between the drug molecule and the host.

Polymer-modified nanoparticles, which can load anticancer drugs such as doxorubicin (DOX), showing the release in response to a specific trigger, have been paid much attention in cancer therapy. In our study, a pH-sensitive drug-delivery system consisting of Fe3O4@mSiO2 core-shell nanocomposite (about 65 nm) and a β-thiopropionate-poly(ethylene glycol) "gatekeeper" (P2) has been successfully synthesized as a drug carrier (Fe3O4@mSiO2@P2). Because of the hydrolysis of the β-thiopropionate linker under mildly acidic conditions, Fe3O4@mSiO2@P2 shows a pH-sensitive release performance based on the slight difference between a tumor (weakly acid) and normal tissue (weakly alkaline). And before reaching the tumor site, the drug-delivery system shows good drug retention. Notably, the nanocomposites are quickly taken up by HeLa cells due to their small particle size and the poly(ethylene glycol) modification, which is significant for increasing the drug efficiency as well as the cancer therapy of the drug vehicles. The excellent biocompatibility and selective release performance of the nanocomposites combined with the magnetic targeted ability are expected to be promising in the potential application of cancer treatment.