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The rheological properties of a pH-sensitive clean fracturing fluid system formed by the anionic surfactant N-hexadecyl iminodiacetic acid (HIA), which has two carboxyl groups, and salt-free cationic hexadecyl trimethyl ammonium bromide (CTAB) have been carefully studied. Viscoelastic wormlike micelles (WLMs) were prepared in a HIA/CTAB hybrid system. The increased electrostatic interactions between the heads of HIA and CTAB lead to a structural transition from spheres to WLMs as a function of pH. Large-scale coarse-grained molecular dynamics (CGMD) revealed that the formation of WLMs can be described in three stages: “oligomer-to-sphere” fusion; “sphere-to-rod” fusion; and “'rod-to-rod” fusion. The simulation results show that electrostatic repulsion occurs among the carboxyl groups of HIA and that HIA is screened by the positively charged heads of CTAB, which leads to an increase in solution viscosity. The excellent rheological properties and pH sensitivity of the clean fracturing fluid significantly improve the seaming capacity and reservoir protection of the fracturing fluid, thus helping to increase the productivity of the well after fracturing and control the construction cost.

The ultrasonication-triggered interfacial assembly approach was developed to synthesize magnetic Janus amphiphilic nanoparticles (MJANPs) for cancer theranostic applications, where the biocompatible octadecylamine is used as a molecular linker to mediate the interactions between hydrophobic and hydrophilic nanoparticles across the oil-water interface. The obtained Co cluster-embedded Fe3O4 nanoparticles-graphene oxide (CCIO-GO) MJANPs exhibited superior magnetic heating efficiency and transverse relaxivity, 64 and 4 times higher than that of commercial superparamagnetic iron oxides, respectively. The methodology has been applicable to nanoparticles of various dimensions (5-100 nm), morphologies (sphere, ring, disk, and rod), and composition (metal oxides, noble metal and semiconductor compounds, etc.), thereby greatly enriching the array of MJANPs. In vivo theranostic applications using the tumor-bearing mice model further demonstrated the effectiveness of these MJANPs in high-resolution multimodality imaging and high-efficiency cancer therapeutics. The ubiquitous assembly approach developed in the current study pave the way for on-demand design of high-performance Janus amphiphilic nanoparticles for various clinical diagnoses and therapeutic applications.

Magnetic-mediated hyperthermia (MMT) is emerging as one of the promising techniques, which could synergistically treat cancer along with current treatment techniques such as chemotherapy and radiotherapy and trigger on-demand release of therapeutic macromolecules. However, the low specific absorption rate and potential in vivo toxicity of magnetic nanomaterials as the MMT mediators restrict the new advancements in MMT treatment. Herein, for the first trial, the unique inductive heating property of hypertonic saline (HTS), a clinically applied solution exhibiting several physiological effects under alternative magnetic field (AMF), was systematically investigated. Though without magnetic property, due to the dipolar polarization under the electromagnetic radiation, HTS can induce enough high and rapid temperature increase upon exposure under AMF. Based on such an observation, PEG-based HTS hydrogel was fabricated for the inhibition of unwanted diffusion of ions so as to ensure the ideal temperature rise at the targeted region for a longer time. Furthermore, an anticancer drug (doxorubicin) was also incorporated into the hydrogel to achieve the magnetic field/pH stimuli-responsive drug-sustainable release as well as synergistic thermochemotherapy. The potential application of the drug-loaded HTS-PEG-injectable hydrogel for breast cancer postsurgical recurrence prevention is demonstrated. Significant in vivo suppression of two kinds of breast cancer models was achieved by the hybrid hydrogel system. This work explores a new biomedical use of clinical HTS and a promising cancer treatment protocol based on HTS-PEG hydrogel for magnetic hyperthermia combined with stimuli-responsive chemotherapy for breast cancer postsurgical recurrence prevention.

The development of a highly efficient, low-toxicity, ultrasmall ferrite nanoparticle-based T1 contrast agent for high-resolution magnetic resonance imaging (MRI) is highly desirable. However, the correlations between the chemical compositions, in vitro T1 relaxivities, in vivo nano-bio interactions and toxicities remain unclear, which has been a challenge in optimizing the in vivo T1 contrast efficacy. Methods: Ultrasmall (3 nm) manganese ferrite nanoparticles (MnxFe3-xO4) with different doping concentrations of the manganese ions (x = 0.32, 0.37, 0.75, 1, 1.23 and 1.57) were used as a model system to investigate the composition-dependence of the in vivo T1 contrast efficacy. The efficacy of liver-specific contrast-enhanced MRI was assessed through systematic multiple factor analysis, which included the in vitro T1 relaxivity, in vivo MRI contrast enhancement, pharmacokinetic profiles (blood half-life time, biodistribution) and biosafety evaluations (in vitro cytotoxicity testing, in vivo blood routine examination, in vivo blood biochemistry testing and H&E staining to examine the liver). Results: With increasing Mn doping, the T1 relaxivities initially increased to their highest value of 10.35 mM-1s-1, which was obtained for Mn0.75Fe2.25O4, and then the values decreased to 7.64 m M-1s-1, which was obtained for the Mn1.57Fe1.43O4 nanoparticles. Nearly linear increases in the in vivo MRI signals (ΔSNR) and biodistributions (accumulation in the liver) of the MnxFe3-xO4 nanoparticles were observed for increasing levels of Mn doping. However, both the in vitro and in vivo biosafety evaluations suggested that MnxFe3-xO4 nanoparticles with high Mn-doping levels (x > 1) can induce significant toxicity. Conclusion: The systematic multiple factor assessment indicated that the MnxFe3-xO4 (x = 0.75-1) nanoparticles were the optimal T1 contrast agents with higher in vivo efficacies for liver-specific MRI than those of the other compositions of the MnxFe3-xO4 nanoparticles. Our work provides insight into the optimization of ultrasmall ferrite nanoparticle-based T1 contrast agents by tuning their compositions and promotes the translation of these ultrasmall ferrite nanoparticles for clinical use of high-performance contrast-enhanced MRI.

Mitochondria-targeting nanotherapy receives great attention these days for its capacity in disrupting mitochondria function and inducing tumor cell apoptosis through external magnetic and optical stimulations. However, the effect is significantly diminished when applied to animal models. The key factors include environmental complexity in vivo and intrinsic protective features of tumor tissues. To address these obstacles and reduce expenses on drug screening, we herein introduce a methodology for producing millimeter-sized spheroids with structural and functional characteristics of tumor tissues in vivo. The necessity of spheroid as a liver tumor model is demonstrated by comparing the effect of TPP-SPIONs (triphenylphosphonium cation-superparamagnetic iron oxide nanoparticles) on monolayer-cultured HepG2 cells and spheroids. Our study reveals that large-scale spheroid, in contrast to monolayer cells, reflects more in vivo tumor characters and is less responsive to TPP-SPIONs during magnetic hyperthermia treatment.

A novel CO2 responsive anionic smart wormlike micelles (SWLMs) was constructed by simply mixing sodium oleate (NaOA) and the small organic counterion 2, 6, 10-trimethyl-2, 6, 10-triazaundecane (TMTAD) in a 3:1 M ratio without complex organic synthesis. After bubbling CO2, TMTAD and NaOA molecules in aqueous solution, a pseudo Gemini surfactant is formed in situ due to electrostatic interactions. This system shows two obvious performance transitions when CO2 is continuously introduced, from a water-like solution to a viscoelastic fluid and then a milky solution. Such transitions reflect the continuous transformation of the self-assembled structure from spherical micelles to wormlike micelles and then vesicle or spherical micelles. Additionally, this system can exhibit two similar sequential transformations when the pH changes in the reverse process.

A new and tri-responsive fluorescent Schiff base probe (DBAB) has been designed and developed for the recognition of iron(III) ions (Fe3+), iron(II) ions (Fe2+) and copper(II) ions (Cu2+) simultaneously. This sensor displays a favorable selectivity for Fe3+, Fe2+ and Cu2+ ions over a range of other common metal cations in DMF solution, leading to prominent fluorescence on–off. The detection limits were 2.17 × 10−6 M for Fe3+, 2.06 × 10−6 M for Fe2+ and 2.48 × 10−6 M for Cu2+ respectively. This tri-responsive fluorescent probe for Fe3+, Fe2+ and Cu2+ was distinguished by further reduction of the ascorbic acid. The recognition mechanism of DBAB toward Fe3+, Fe2+ and Cu2+ has been investigated in detail by Job plot measurements and 1H NMR.

Remote modulation of nanoscale biochemical processes in a living system using magnetic stimulation is appealing but is restricted by the lack of a highly efficient nanomediator which can deliver timely and effective response to biological molecules under an external magnetic field. Herein, we report the development of a novel nanocatalyst based on a ferrimagnetic vortex-domain nanoring (FVIO)-enzyme hybrid that enables real-time modulation of enzymatic catalysis under an alternating magnetic field (AMF). The role of the FVIO is to provide localized heating immediately upon exposure to an AMF, which efficiently and selectively promotes the activity of conjugated enzymes on the surface. The reaction rate of the as-fabricated FVIO-β-Gal hybrid was shown to be boosted up to 180% of its initial value by localized heat generated under an AMF of 550 Oe in less than 2 s and without heating up the bulk solution. Moreover, the degree of activity acceleration was shown to be tunable by increasing the strength of the AMF. The concept of remote magnetic stimulation of enzymatic reactions has been further applied to other enzymes (e.g. FVIO-KPC and FVIO-GOx), demonstrating the general applicability of this strategy. Since almost all metabolic processes in cells rely on enzymatic catalysis to sustain life, the FVIO-enzyme system developed in this work provides a valuable nanoplatform for spatiotemporally manipulating biochemical reactions, which might pave the way for future remote manipulation of living organisms.

Developing multifunctional theranostic nanoplatforms with high tumor therapeutic efficacy is the focus area of nanomedicine. In this study, we have designed Fe3O4–Pd Janus nanoparticles (JNPs) with dual-mode magnetic resonance imaging/photoacoustic (MRI/PA) imaging properties for magnetic-photo hyperthermia and chemodynamic therapy simultaneously. Due to the magnetic-photothermal properties of Fe3O4 nanoparticles and plasmonic photothermia effect of Pd nanosheets, the combined Fe3O4–Pd JNPs can achieve synergistic heating effects of 1 + 1 > 2. It is demonstrated that Fe3O4–Pd JNPs reached a higher temperature enhancement under alternating magnetic field (AMF) plus laser irradiation than the corresponding individual modality (only AMF or laser irradiation alone for Fe3O4–Pd JNPs) or the sum of two individual modalities. Besides amplified magnetic-photo heating, Fe3O4–Pd JNPs also enhanced ROS generation due to the interface synergistic effect in producing hydroxyl radicals (˙OH), which is realized by Fe3O4 nanoparticle-based Fenton reaction and Pd nanosheet-based catalytic properties in the presence of H2O2 in an acidic environment. Remarkably, the ROS level could be further elevated under external AMF plus laser irradiation. The in vivo anti-tumor effect of Fe3O4–Pd JNPs was evaluated on a 4T1 orthotopic mouse breast cancer model. The results showed that Fe3O4–Pd JNPs enable complete tumor inhibition without appreciable adverse effects under AMF plus laser irradiation, guided by MRI/PA dual-mode imaging with a high spatial resolution and accuracy. This study provides an alternative way for cancer therapy by on-demand design of high-performance theranostic nanoplatforms according to the characteristics of the tumor microenvironment and the intriguing physiochemical properties of inorganic nanomaterials.

Interfacial tension and emulsification are important to enhance oil recovery. There is almost none quantitative research on their correlation for Daqing crude oil. Experiments are performed to find out the correlation between different interfacial tension, emulsification and chemical flooding oil displacement efficiency. The authors changed the structure of surfactant to make characteristics of interfacial tension different significantly and build the relationship between interfacial tension parameters and chemical flooding oil displacement efficiency by physical simulate experiments. The ultralow interfacial tension index (expressed by S) is established by orthogonal test and actual significance of interfacial tension curves. The fitting formula between S and chemical flooding oil displacement efficiency (E) is: E = 0.856 ln(S) + 13.849. The emulsifying ability includes two aspects O/W and W/O. Authors changed the structure of surfactant to make characteristics of ASP systems have similar interfa...

Molecular modeling of CO2-polymer system was established to study the molecular behaviors and intermolecular interaction of copolymers in supercritical carbon dioxide (SC-CO2) by all-atom molecular dynamics (MD) simulation. According to the simulation results, the correlations of the intermolecular interaction with the molecular structure and composition were explored. The effects of intermolecular interactions on the copolymer properties in SC-CO2 were identified. A series of copolymers were synthesized with CO2-philic monomer 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-Heptadecafluorodecyl acrylate (HFDA) and CO2-phobic monomer vinyl n-Octanoate (VOc), vinyl acetate (VAc), vinyl pivalate (VPi), respectively. The solubility and viscosification of the copolymers in SC-CO2 were evaluated by cloud point pressure and relative viscosity measurements. It was found that P(HFDA0.49-co-VAc0.51), which is the most effective thickener among the copolymers, could enhance the viscosity of SC-CO2 by 62 times at 5 wt%. It was suggested that the thickening capability of the copolymers in SC-CO2 may originate from intermolecular cross-links generated by associative groups. Combining the molecular simulation and experiment results, the structure-activity relationships of the copolymers in SC-CO2 were revealed. It is believed that the molecular simulation aided design method for the SC-CO2 copolymer thickener is reliable.

Ferrite nanoparticles have been widely used in the biomedical field (such as magnetic targeting, magnetic resonance imaging, magnetic hyperthermia, etc.) due to their appealing magnetic properties. In tumor acidic microenvironment, ferrite nanoparticles show intrinsic peroxidase-like activities, which can catalyze the Fenton reaction of hydrogen peroxide (H2O2) to produce highly toxic hydroxyl free radicals (•OH), causing the death of tumor cell. Recent progresses in this field have shown that the enzymatic activity of ferrite can be improved via converting external field energy such as alternating magnetic field and near-infrared laser into nanoscale heat to produce more •OH, enhancing the killing effect on tumor cells. On the other hand, combined with other nanomaterials or drugs for cascade reactions, the production of reactive oxygen species (ROS) can also be increased to obtain more efficient cancer therapy. In this review, we will discuss the current status and progress of the application of ferrite nanoparticles in ROS-mediated cancer therapy and try to provide new ideas for this area.

Engineering the protein corona (PC) on nanodrugs is emerging as an effective approach to improve their pharmacokinetics and therapeutic efficacy, but conventional in vitro pre-programmed methods have shown great limitation for regulation of the PC in the complex and dynamic in vivo physiological environment. Here, we demonstrate an magnetothermal regulation approach that allows us to in situ modulate the in vivo PC composition on iron oxide nanoparticles for improved cancer nanotherapy. Experimental results revealed that the relative levels of major opsonins and dysopsonins in the PC can be tuned quantitatively by means of heat induction mediated by the nanoparticles under an alternating magnetic field. When the PC was magnetically optimized in vivo, the nanoparticles exhibited prolonged circulation and enhanced tumor delivery efficiency in mice, 2.53-fold and 2.02-fold higher respectively than the control. This led to a superior thermotherapeutic efficacy of systemically delivered nanoparticles. In vivo magnetothermal regulation of the PC on nanodrugs will find wide applications in biomedicine.

Ultrasmall ferrite nanoparticles (UFNPs) have emerged as powerful magnetic resonance imaging (MRI) T

Magnetic hyperthermia (MH) mediated by magnetic nanoparticles is one of the most promising antitumor modalities. The past several decades have witnessed great progress for MH antitumor therapy in scientific trials and clinic applications since it was initially advanced by Gilchrist et al. The ultimate object of MH in vivo is to efficiently kill cancer cells, and hence, it is of great importance to develop an optimized cellular MH method to evaluate the therapeutic efficiency in vitro. In this study, we systematically studied the considerable affecting factors of cancer cell-killing efficiency during the cellular MH process, including the region of cell vessel positioned inside the alternating magnetic field copper coil, the magnetic field amplitude, the types of cancer cells, etc. Taking all these into account, we introduced a method for standardizing the cellular MH process to evaluate the cell-killing efficiency.

Reactive oxygen species (ROS), a group of oxygen derived radicals and derivatives, can induce cancer cell death via elevated oxidative stress. A spatiotemporal approach with safe and deep‐tissue penetration capabilities to elevate the intracellular ROS level is highly desirable for precise cancer treatment. Here, a mechanical‐thermal induction therapy (MTIT) strategy is developed for a programmable increase of ROS levels in cancer cells via assembly of magnetic nanocubes integrated with alternating magnetic fields. The magneto‐based mechanical and thermal stimuli can disrupt the lysosomes, which sequentially induce the dysfunction of mitochondria. Importantly, intracellular ROS concentrations are responsive to the magneto‐triggers and play a key role for synergistic cancer treatment. In vivo experiments reveal the effectiveness of MTIT for efficient eradication of glioma and breast cancer. By remote control of the force and heat using magnetic nanocubes, MTIT is a promising physical approach to trigger the biochemical responses for precise cancer treatment., A magnetomechanical thermal induction therapy (MTIT) strategy is developed based on a single platform of assembly of magnetic nanocubes coupled with alternating magnetic fields. There is a synergistic effect between mechanical responses and thermal properties, which is highly efficient both in vitro and in vivo. The mechanisms of the synergistic effect are investigated, which can be attributed to the manipulation of biochemical reactive oxygen species (ROS) signal level. This MTIT strategy holds potential for precise treatment of deep‐seated tumors in a spatiotemporal controllability.

Uniform magnetic nanoparticle-loaded polymer nanospheres with different loading contents of manganese ferrite nanoparticles were successfully synthesized using a flexible emulsion process. The MnFe2O4-loaded polymer nanospheres displayed an excellent dispersibility in both water and phosphate buffer saline. The effect of loading ratio and size of MnFe2O4 nanoparticles within the nanospheres on the specific absorption rate (SAR) under an alternating magnetic field was investigated. Our results indicate that a large size (here 18 nm) and a low loading ratio are preferable for a high SAR. For a smaller particle size (6 nm), the low loading ratio did not result in an enhancement of the SAR value, while a very low SAR value is expected for 6 nm. In addition, the SAR of low-content MnFe2O4 (18 nm)-loaded polymer nanospheres in the agarose gel which is simulated for in vivo environment is the highest among the samples and does not change substantially in physiological environments. This differs largely from the behaviour of singly dispersed nanoparticles. Our results have paved the way for the design of MnFe2O4-loaded polymer nanospheres as magnetic hyperthermia agents for in vivo bio-applications.

DOX-loaded magnetic alginate–chitosan microspheres (DM-ACMSs) were developed as a model system to evaluate alternating magnetic field (AMF)-responsive, chemo-thermal synergistic therapy for multimodality postsurgical treatment of breast cancer. This multimodality function can be achieved by the combination of DOX for chemotherapy, with superparamagnetic iron oxide nanoparticles (SPIONs) as magnetic hyperthermia agents and drug release trigger. Both moieties are encapsulated in ACMSs which also allow on-demand drug release. It is demonstrated that the optimized SPION content in DM-ACMSs is about 0.29 mg Fe, at which DM-ACMSs could exhibit the best hyperthermia performance. Under a remote AMF, DM-ACMs can quickly reach a 22.5% cumulative drug release in the tumor site within 10 min upon exposure under AMF, whereas only 0.2% DOX is released in the absence of AMF. Furthermore, a comparison study of AMF and water bath as heating source indicates that the cumulative drug release amount upon AMF exposure is twice that by water bath heating. Further analysis revealed that the AMF stimulated drug release is driven by both thermal and concentration gradient from inside to outside, which can be well-described by the coupling mechanism of mass and heat transfer using the Soret diffusion model. In vitro cytotoxicity tests on MCF-7 breast cancer cells show that the combined therapy based on DM-ACMSs leads to 95.5% cell death, about 1.5-fold and 1.1-fold higher than that of single magnetic hyperthermia or chemotherapy, respectively. The in vivo anti-tumor effect on tumor-bearing mice demonstrates that the residual tumor disappears in 12 days after chemo-thermal synergistic treatment using DM-ACMSs, and there is no recurrence in the entire experiment period (40 days) as compared to 25 days recurrence for single-modality treatment. Our results not only provide an innovative DM-ACMSs system as a stimuli-responsive, synergistic chemo-thermal therapy platform for efficient reduction in the recurrence of breast cancer, but also provide insight into the intricate interplay of the functional components in magnetic hydrogel microspheres.

Owing to their unique physicochemical properties and comparable size to biomacromolecules, functional nanostructures have served as powerful supports to construct enzyme-nanostructure biocatalysts (nanobiocatalysts). Of particular importance, recent years have witnessed the development of novel nanobiocatalysts with remarkably increased enzyme activities. This review provides a comprehensive description of recent advances in the field of nanobiocatalysts, with systematic elaboration of the underlying mechanisms of activity enhancement, including metal ion activation, electron transfer, morphology effects, mass transfer limitations, and conformation changes. The nanobiocatalysts highlighted here are expected to provide an insight into enzyme–nanostructure interaction, and provide a guideline for future design of high-efficiency nanobiocatalysts in both fundamental research and practical applications.

Utilizing the iron-carrying nanomaterials for Fenton chemistry mediation to catalyze decomposition of hydrogen peroxide and generate toxic hydroxyl radical (OH) has drawn much attention in antimicrobial therapy field. However, these nanomaterials are usually with unsatisfactory catalytic efficacy and lack of the capacity to modulate the catalytic activity, which may give the bacteria opportunity in developing resistance against the antibacterial treatment. Herein, we systematically investigated the influence of alternating magnetic field (AMF) on the catalytic activity and antibacterial efficiency of the amorphous iron nanoparticles (AIronNPs). With rapidly ionized and the AMF augmented chemodynamic effect, the AIronNPs can convert low concentration of H2O2 into more OH, the possible mechanism might be attributed to the accelerated ferrous iron ions releasing with AMF exposure. As a proof of concept, the AIronNPs and AMF synergetic antibacterial system have shown excellent broad-spectrum antimicrobial properties, 91.89% antibacterial efficiency is shown toward Escherichia coli and 92.65% toward Staphylococcus aureus. It also facilitated the formation of granulation tissue and accelerated wound healing on in vivo infected model, whereas AIronNPs alone have limited effect. We believe this work will broaden the thoughts for spatiotemporally manipulating the catalytic activity of nanomaterials and advance the development of magnetic nano-antibiotics in the antibacterial field.

Water flooding is widely used for recovering crude oil from unconventional reservoirs due to its economic feasibility. At reservoir conditions, the injected water is usually imbibed into fractured rocks, so-called spontaneous imbibition, providing a considerable driving force for enhancing oil recovery. In this work, spontaneous imbibition on a rock surface is investigated at high-pressure conditions, and its influence on tight oil recovery is revealed from a pore-scale perspective. Specifically, three typical core samples are selected and characterized to obtain their pore-size distribution by applying the NMR technique. These core samples are then saturated with crude oil and are submerged in formation water, which is filled in a high-pressure vessel. Oil recovery efficiency as well as the imbibition rate is consequently calculated for specific pores during spontaneous imbibition. Test results indicate that oil recovery from spontaneous imbibition is different in different pores depending on the petrophysical properties of the tight cores. That is, the difference in imbibition efficiency between small and large pores decreases as permeability and porosity increase in the core samples. In addition, as for core samples #1 and #2, the imbibition rate usually reaches a maximum at the initial imbibition stage. However, as for core sample #3, the maximum imbibition rate is far delayed due to high capillarity. This work may reveal the fundamental mechanism of the influence of spontaneous imbibition on a rock surface at high-pressure conditions on tight oil recovery from a pore-scale perspective.

The “graft onto” method is used to obtain the “stimuli-responsive water-soluble polymer” with low concentration, where 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and n-hydroxysulfosuccinimide sodium salt as catalyst and sodium polyacrylate as backbone chain. The molecular structure of the polymer is characterized by Nuclear Magnetic Resonance (1H NMR). The influence of temperature on polymer rheological properties and aggregation is studied by rheometer and fluorescence probe respectively. The results show that when the polymer concentration is higher than 1500 mg/L, the thickening properties can be controlled by diacetoneacrylamide, thermal-responsive monomer, NaCl and polymer concentration, where the apparent viscositymax/ viscositymin (ηmax/ηmin) changes from 18.3 to 39.4, from 2.6 to 45.5, from 9.3 to 36, from 7.8 to 36.9 respectively and the lower critical solution temperature (LCST) changes from 60 °C to 40 °C. The reason for the polymer with controllable thickening properties is that the thermal-responsive monomers change from hydrophilicity to hydrophobicity, thus forming aggregations. At this time, the polymer chains form network structures. Because of controllable thickening properties at low concentration, it has potential application prospects.

Evaluating enzyme activity intracellularly on natural substrates is a significant experimental challenge in biomedical research. We report a label-free method for real-time monitoring of the catalytic behavior of class A, B, and D carbapenemases in live bacteria based on measurement of heat changes. By this means, novel biphasic kinetics for class D OXA-48 with imipenem as substrate is revealed, providing a new approach to detect OXA-48-like producers. This in-cell calorimetry approach offers major advantages in the rapid screening (10 min) of carbapenemase-producing Enterobacteriaceae from 142 clinical bacterial isolates, with superior sensitivity (97 %) and excellent specificity (100 %) compared to conventional methods. As a general, label-free method for the study of living cells, this protocol has potential for application to a wider range and variety of cellular components and physiological processes.

Weiming Xue,1 Yanyan Liu,1 Na Zhang,1 Youdong Yao,2 Pei Ma,1 Huiyun Wen,1 Saipeng Huang,1 Yane Luo,3 Haiming Fan4 1School of Chemical Engineering, Northwest University, Xi’an, Shaanxi 710069, China; 2Pediatrics, Egang Hospital, Ezhou, Hubei 436000, China; 3College of Food Science and Technology, Northwest University, Xi’an, Shaanxi 710069, China; 4Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi’an, Shaanxi 710069, China Introduction: In vivo distribution of polyethylene glycol (PEG)ylated functional nanoparticles is vital for determining their imaging function and therapeutic efficacy in nanomedicine. However, contradictory results have been reported regarding the effect of core size and PEG surface of the nanoparticles on biodistribution.Methods: To clarify this ambiguous understanding, using iron oxide nanoparticles (IONPs) as a model system, we investigated the effect of core size and PEG molecule weights on in vivo distribution in mice. Three PEGylated IONPs, including 14 nm IONP@PEG2,000, 14 nm IONP@PEG5,000, and 22 nm IONP@PEG5,000, were prepared with a hydrodynamic size of 26, 34, and 81 nm, respectively. The blood pharmacokinetics and tissue distribution were investigated in detail.Results: The results indicated that the PEG layer, rather than core size, played a dominant role in determining the half-life time of IONPs. Specifically, increased molecular weight of the PEG layer led to a longer half-life time. These PEGylated IONPs were mainly excreted by liver clearance. While the PEG molecular layer constituted the key factor to determine the clearance ratio, core size affected the clearance rate.Conclusion: Complete blood count analysis and histopathology suggested excellent biocompatibility of PEGylated IONPs for future clinical trials. Keywords: IONPs, pharmacokinetics, tissue distribution, metabolism, histocompatibility

Molybdenum disulfide (MoS2), a typical transition-metal dichalcogenide, has attracted increasing attention in the field of nanomedicine because of its preeminent properties. In this study, magnetic resonance imaging (MRI)-guided chemo-photothermal therapy of human breast cancer xenograft in nude mice was demonstrated using a novel core/shell structure of Fe3O4@MoS2 nanocubes (IOMS NCs) via the integration of MoS2 (MS) film onto iron oxide (IO) nanocubes through a facile hydrothermal method. After the necessary PEGylation modification of the NCs for long-circulation purposes, such PEGylated NCs were further capped by 2-deoxy-D-glucose (2-DG), a non-metabolizable glucose analogue to increase the accumulation of the as-prepared NCs at the tumor site, as 2-DG molecules could be particularly attractive to resource-hungry cancer cells. Such 2-DG-modified PEGylated NCs (IOMS-PEG-2DG NCs) acted as drug-carriers for doxorubicin (DOX), which could be easily loaded within the NCs. The obtained IOMS-PEG(DOX)-2DG NCs exhibited a T2 relaxivity coefficient of 48.86 (mM)−1·s−1 and excellent photothermal performance. 24 h after intravenous injection of IOMS-PEG(DOX)-2DG NCs, the tumor site was clearly detected by enhanced T2-weighted MRI signal. Upon exposure to an NIR 808-nm laser for 5 min at a low power density of 0.5 W·cm−2, a marked temperature increase was noticed within the tumor site, and the tumor growth was efficiently inhibited by the chemo-photothermal effect. Therefore, our study highlights an excellent theranostic platform with great potential for targeted MRI-guided precise chemo-photothermal therapy of breast cancer.

Functional nanoparticles possess great potential for precise diagnosis and optimum therapy of serious diseases. However, their application is limited by structural heterogeneity and physical properties, low drug-loading efficiency, the absence of effective drug release, and some undetermined physiological and biochemical properties. Effective surface modification is able to overcome these limitations and largely improve the application performance of functional nanoparticles in biomedicine. Nevertheless, chemical or physical surface modifications using conventional surfactants are difficult to ensure homogeneous construction and normal metabolism of nanoparticles in vivo. Recent progress in this field has demonstrated that nucleic acid-modified nanoparticles can attain efficient transport, steady state and rational metabolism, as well as clear targeting and controllable drug release. All of these advantages are attributed to the special steric structure, homology, and biological functions of nucleic acids. Moreover, abundant active sites on the nucleic acid skeleton not only facilitate the direct or indirect connection of nanoparticles, but also support retention of the functions of both nanoparticles themselves and nucleic acids. In this review, we summarize the outstanding respective characteristics and prospects of nucleic acid-modified nanoparticles. In addition, primary surface modification techniques for preparing nucleic acid-modified nanoparticles, including non-scaffold-mediated modification and scaffold-mediated modification, were highlighted. Furthermore, interactions between nanoparticles and nucleic acids, as well as the effects of modification techniques on the properties of nucleic acid modified nanoparticles, are discussed in detail.

Mesoderm is derived from the primitive streak. The rostral region of the primitive streak forms the somitic mesoderm. We have previously shown the developmental origin of each level of the somitic mesoderm using DiI fluorescence labeling of the primitive streak. We found that the more caudal segments were derived from the primitive streak during the later developmental stages. DiI labeled several pairs of somites and showed the distinct rostral boundary; however, the fluorescence gradually disappeared in the caudal region. This finding can be explained in two ways: the primitive streak at a specific developmental stage is primordial of only a certain number of pairs of somites, or the DiI fluorescent dye was gradually diluted within the primitive streak by cell division. Here, we traced the development of the primitive streak cells using enhanced green fluorescent protein (EGFP) transfection. We confirmed that, the later the EGFP transfection stage, the more caudal the somites labeled. Different from DiI labeling, EGFP transfection performed at any developmental stage labeled the entire somitic mesoderm from the anterior boundary to the tail bud in 4.5-day-old embryos. Furthermore, the secondary neural tube was also labeled, suggesting that not only the somite precursor cells but also the axial stem cells were labeled.

In recent years, multifunctional nanoparticles have attracted much research interest in various biomedical applications such as biosensors, diagnosis, and drug delivery systems. In this study, we report an NIR imaging diagnosis and therapy nanoplatform which is developed by complexing upconversion nanoparticles (UCNP@OA) NaLuF4:Er3+,Yb3+ with nanographene oxide (NGO). The obtained nanocomposites UCNP@NGO showed excellent stability and low cell toxicity, which not only acted as upconversion luminescence (UCL) probes for tumor imaging, but also served as therapy agents by converting laser energy into thermal energy for photothermal therapy (PTT) with high photothermal conversion efficiency. This work highlights the potential of UCNP@NGO nanocomposites as an integrated theranostic nanoplatform for the UCL image combinatorial PTT of cancer, providing a promising candidate for clinical antitumor treatments.

Three-dimensional hierarchical metal oxide core/shell nanowire arrays (HMONAs) have become promising pseudocapacitive materials due to their integrated smart architectures. However, these core/shell nanostructures have unsatisfactory structural stability and frequently suffer destruction during their fabrication process and their charge–discharge cycles, thus limiting their application lifespan. Herein, a general strategy based on the minimization of the lattice mismatch between the shell and the backbone at the nanoscale interface has been proposed to improve the cycling stability of the HMONAs. This strategy is achieved by a facile hydrothermal pretreatment under mild acidic condition, where a selective dissolution process occurs for interface optimization. To prove the concept, three typical HMONAs, α-MnO2 nanotube@δ-MnO2 nanosheet core/shell arrays, α-MnO2 nanotube@NiO nanosheet core/shell arrays and Co3O4@MnO2 core/shell nanoarrays, were synthesized for interface optimization. It was found that these thermodynamically unstable nanostructures in the shells of HMONAs can be selectively dissolved under a hydrothermal process, leading to enhanced stability of HMONAs. The comparison study indicates that all treated HMONAs exhibit excellent capacitance retention of 93.2% (MnO2@MnO2), 94.3% (MnO2@NiO) and 95.3% (Co3O4@MnO2) after 5000 cycles, which are 22.9%, 9.3% and 20.1% higher, respectively, than those of the untreated HMONAs. Furthermore, the symmetrical supercapacitors based on treated MnO2@MnO2 nanoarrays electrodes also demonstrate 92% capacitance retention after 5000 cycles, showing better comprehensive performance than their untreated counterpart (78% capacitance retention). The general strategy of nanoscale interface optimization provides new opportunities in pushing the cycling stability limit of HMONAs.

In this article, a series of sulfate Gemini surfactants with different lengths of hydrophobic tail chains and spacer groups were synthesized. Both 1H NMR spectra and mass spectrometry analysis verified that the synthesized products were sulfate Gemini surfactants. Krafft temperatures indicated that they showed better water solubility at low temperatures. The conductivity of the sulfate Gemini surfactant versus concentration under different temperature conditions was tested. The influence of the hydrophobic tail chain, spacer group, and temperature on the critical micelle concentration and micelle thermodynamic parameters were revealed. The structure–activity relationship between the molecular structure and the foaming performance was discussed. Finally, we studied the influence of temperature on the foaming performance, foam stabilization, and rheological properties of the foam system. The insights gained from this study may enrich theoretical research on sulfate Gemini surfactants and promote the applications of sulfate Gemini surfactants in various fields.

Intercalation pseudocapacitance is emerging as a highly promising mechanism for high rate energy storage applications. However, it is still debatable how the alkali metal ion pre-intercalation in layered metal oxides affects the intercalation pseudocapacitance. Herein，the layered birnessite-MnO 2 nanoflakes with K + pre-intercalation were in- situ fabricated on the graphene foam via a one-step facile hydrothermal method. The amount of pre-intercalated K + can be controlled by adjusting the reaction parameter. The electrochemical tests indicate that the amount of pre-intercalated ions has the optimal value and intercalated slight or excessive amount of ions may lead to the pseudocapacitance decline. The K 0.19 MnO 2 /graphene foam electrode shows a high pseudocapaitance of 344 F g −1 (based on the mass of the whole electrode) at a scan rate of 2 mV s −1 , which is the best among the as-prepared samples. Cycling tests demonstrate that the pre-intercalated K + can greatly improve the cycling stability of layered birnessite-MnO 2 nanoflakes. This work provides new insights on understanding the role of pre-intercalation ions and brings new strategies to further improve the performance of layered metal oxide electrodes.

Magnetic nanomaterials have been widely used in various biomedical applications, which have seen accelerating interest since the breakthrough in the chemical synthesis of monodispersed iron oxide nanoparticles. Magnetic iron oxide nanoparticles (MIONs) possess excellent biocompatibility, and they can produce multiple physicochemical effects when exposed to magnetic fields. Due to this rapid development in MIONs for cancer diagnosis and therapy, it becomes necessary to present a comprehensive review paper from the biomedical engineering perspective. This review will present an overview of the recent synthesis methods used in the preparation of magnetic nanomaterials. We will then focus on the application of magnetic nanomaterials in imaging and therapy technology, and we will also evaluate their biosafety in vitro, in vivo, and clinical aspects. The therapeutic effects of magnetic theranostics, magnetocatalytic therapy, magnetically targeted therapy, and magnetothermal therapy under the guidance of imaging diagnosis will also be discussed in this review. Finally, we will briefly analyze the challenges of implementing magnetic nanomaterials as a nano-platform for imaging diagnosis and treatment, and we will also offer suggestions for future research in this field.

Functional nanomaterials such as iron oxide nanoparticles have been extensively explored for the diagnosis and treatment of central nervous system diseases. However, an insufficient understanding of the comprehensive nanomaterial-biological interactions in the brain hinders the nanomaterials from meeting the medical requirements for translational research. Here, FDA-approved ferumoxytol, an iron oxide nanoparticle, is chosen as the model nanomaterial for a systematic study of the dynamic interactions between ferumoxytol and immune cells, including microglia and macrophages, in the brain tumors. Strikingly, up to 90% of intratumorally injected ferumoxytol nanoparticles are recognized and phagocytized by tumor-associated microglia and macrophages. The dynamic trafficking progress of ferumoxytol in microglia and macrophages, including scavenger receptor-mediated endocytosis, lysosomal internalization, and extracellular vesicle-dominated excretion, is further studied. Importantly, the results demonstrate that extracellular vesicle-encapsulated nanoparticles could be gradually eliminated from the brain along with cerebrospinal fluid circulation over 21 days. Moreover, ferumoxytol exhibits no obvious long-term neurological toxicity after its injection. The study suggests that the dynamic biointeractions of nanoparticles with immune cells in the brain exert a key rate-limiting impact on the efficiency of targeting tumor cells and their in vivo fate and thus provide a deeper understanding of the nanomaterials in the brain for clinical applications.

To investigate the value of motion-corrected (MOCO) phase-sensitive inversion recovery (PSIR) late gadolinium enhancement (LGE) compared with single-shot balanced steady-state gradient echo ("TrueFISP", Siemens) PSIR in free breathing paediatric patients.In this retrospective study, 238 paediatric patients underwent clinical contrast-enhanced cardiovascular magnetic resonance imaging (CMRI). Both the single-shot TrueFISP PSIR and MOCO PSIR sequences were performed on each child. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Two radiologists rated the quality of the images on a scale of 1-5 (1 = poor, 5 = very good). Bland-Altman, linear regression, and intraclass correlation coefficient were used to compared the extent of LGE of the single-shot TrueFISP PSIR and MOCO PSIR. Imaging artefacts were described and compared.Children ranged in age from 60 days to 17 years with an average age of 8.1 ± 3.8 years. MOCO PSIR had higher SNR and CNR than the single-shot TrueFISP PSIR (p0.001). Mean quality ratings for short-axis imaging were 4 (interquartile range, 3-4) for single-shot TrueFISP PSIR and 4 (interquartile range, 4-5) for MOCO PSIR (p0.001). The scan time was faster for single-shot TrueFISP PSIR than for MOCO PSIR. The myocardial LGE results were similar with high agreement between the single-shot TrueFISP PSIR and MOCO PSIR (ICC = 0.955-0.986).The MOCO PSIR sequence is feasible in children. MOCO PSIR is robust at high heart rates and can be performed without breath-holding with higher image-quality ratings than the single-shot TrueFISP PSIR.

MoS2 nanosheets were doped with vanadium (V) with a variety of concentrations using a hydrothermal method. Raman, X-ray photoelectron spectroscopy, and electron paramagnetic resonance results indicate the effective substitutional doping in MoS2. Without V doping, oxides such as MoO2 and MoO3 have been observed, whereas with 5 at% V doping, the oxide disappeared. Magnetic measurements show that room temperature ferromagnetism has been induced by V doping. Magnetization tends to increase with the increased V doping concentration. A very large coercivity up to 1.87 kOe has been observed in 5 at% vanadium doped MoS2, which may attribute to a combination effect of localized charge transfer between V and S ions, pinning effect due to the in-between defects, stress induced by doping, and shape anisotropy due to two-dimensional nature of MoS2 ribbons.

Oil spill accident and oily water have potential risks to environment and human health, thus need to be imperatively treated. Herein, a magnetic fibrous sorbent was designed via electrospinning of suspension containing polymer and magnetic nanoparticles in one step for remote and efficient oil adsorption. The morphology of the magnetic fibrous sorbent was characterized by scanning electron microscopy. The magnetic property and the wetting behavior were measured by vibrating sample magnetometer and contact angle system, respectively. The results showed that the morphology of the fibers was homogeneous and the magnetic nanoparticles were well dispersed within the fibers. It was also found that this composite sorbent had good magnetic response, special wettability, and remote oil adsorption capacity. We believed this novel polymer/Fe3O4 fibrous sorbent could be used as a promising material for the remote oil/water separation.

Enhancement of Fe3O4/Au nanoparticles (Fe3O4/Au NPs) catalyst was observed in the oxidative degradation of methyl orange by employing H2O2 as oxidant. To evaluate the catalytic activity of Fe3O4/Au nanoparticles, different degradation conditions were investigated such as the amounts of catalyst, H2O2 concentration and pH value. Based on our data, methyl orange was degraded completely in a short time. The enhanced catalytic activity and increased oxidation rate constant may be ascribed to synergistic catalyst-activated decomposition of H2O2 to •OH radical, which was one of the strong oxidizing species. Besides, Fe3O4/Au nanoparticles have exhibited satisfying recycle performance for potential industrial application.

High quality porous ZnO nanoplates with a pure crystal phase of hexagonal wurtzite structure were fabricated by thermal decomposition route for the first time. Electron microscopy investigations show that each porous ZnO nanoplates has a single-crystalline nature, which is self-assembled by tiny nanocrystals. The size and pore density of the ZnO nanoplates can be tuned by only changing the amount of zinc source. Magnetic investigations show that the magnetic phase can be converted from paramagnetism to ferromagnetism at room temperature, by increasing the pore density of ZnO nanoplates. The ZnO nanoplates with highest pore density show a d° room-temperature ferromagnetic characteristic, and the saturation magnetization reaches 26 memu/g. Several experimental evidences, including XPS, PL and ESR spectra, demonstrate that the defects of singly charged oxygen vacancies related to the pore density contribute to the long-range ferromagnetic ordering in the dopant-free porous ZnO nanoplates. This finding suggests that the pore-dependent ferromagnetism can be manipulated by tuning the surface-volume ratio, which is significant for the understanding and exploration of diluted magnetic semiconductors.

Large-scale synthesis of monodisperse ultrasmall metal ferrite nanoparticles as well as understanding the correlations between chemical composition and MR signal enhancement is critical for developing next-generation, ultrasensitive T1 magnetic resonance imaging (MRI) nanoprobes. Herein, taking ultrasmall MnFe2O4 nanoparticles (UMFNPs) as a model system, we report a general dynamic simultaneous thermal decomposition (DSTD) strategy for controllable synthesis of monodisperse ultrasmall metal ferrite nanoparticles with sizes smaller than 4 nm. The comparison study revealed that the DSTD using the iron-eruciate paired with a metal-oleate precursor enabled a nucleation-doping process, which is crucial for particle size and distribution control of ultrasmall metal ferrite nanoparticles. The principle of DSTD synthesis has been further confirmed by synthesizing NiFe2O4 and CoFe2O4 nanoparticles with well-controlled sizes of ∼3 nm. More significantly, the success in DSTD synthesis allows us to tune both MR and b...

Fe3O4 nanoparticles synthesized via thermal decomposition in the organic phase have attracted tremendous research interest because of their unique morphology, size dispersion, and crystallinity. However, their poor water dispersibility strongly limited their development in biomedical applications. Therefore, a phase-transfer strategy through which hydrophobic nanoparticles with good performance in the aqueous phase can be obtained is an extremely critical issue. Herein, we present a large-scale, facile, highly efficient strategy for the phase transfer of oleic acid-coated Fe3O4 nanoparticles via a reverse-micelle-based oxidative reaction. The reverse micelle system improves the efficiency of the interface oxidative reaction and prevents the aggregation of nanoparticles during the reaction, facilitating the transfer of Fe3O4 nanoparticles from the organic phase to the aqueous phase. The transferred Fe3O4 nanoparticles are used as a T2 contrast agent to perform magnetic resonance imaging of CNE2 cells (naso...

The influence of salt and temperature on the viscosity of a hydrophobically modified polyacrylamide-based (PAM-based) novel functional polymer (RH-4) was investigated. To study the viscosifying mechanism in brine solution, scanning electron microscope (SEM) was applied to observe the network microstructures of polymer solution. The solution apparent viscosity behaviors of the RH-4 polymer are studied as functions of concentrations, pH value, salt types and amount, microscopic morphology. The viscoelasticity of aqueous solutions of RH-4 polymer changed with shear rate under high salinity condition. Additionally, the influence of temperature on the apparent viscosity of RH-4 polymer was investigated. The results showed that the viscosity decreased at lower salt concentrations and increased at higher salt concentrations. The SEM results show that the network structures of RH-4 polymer become much more condense at high salinity, which lead to the increasing its apparent viscosity. When the salinity reaches 80,000 mg/L, thickening ability of the system is the strongest. With the rise in temperature, the viscosity of polymer solutions with various concentrations decreases slightly except for the two concentrations of 1000 mg/L and 1100 mg/L, their viscosity increases with the increasing of temperature. The thickening tendency is enhanced by high salinity and high temperature, which makes it more promising for EOR.

In this study, styrene/heptadecafluorodecyl acrylate (St–HFDA) copolymers of different compositions were synthetized for the purpose of thickening supercritical carbon dioxide (SC-CO2). The cloud point pressures of the copolymer–CO2 mixtures and the thickening effects of these copolymers for SC-CO2 were measured. Molecular dynamics (MD) simulations were used to evaluate the intermolecular interactions and microstructures of polymer–CO2 systems, the copolymer–CO2 interaction energy, cohesive energy density (CED), solubility parameter, equilibrium conformations and radial distribution functions (RDFs) were obtained, which provided useful information for microscopic understanding on the thickening capability of copolymers in SC-CO2. It was found that all the synthesized St–HFDA copolymers induced greater viscosity enhancements of SC-CO2 compared to poly(Heptadecafluorodecyl acrylate) (PHFDA), and π–π stacking of the Styrene (St) groups played a key role in thickening SC-CO2. On one hand, the introduction of the St groups into PHFDA weakened the CO2-philicity of the polymers by reducing the polymer–CO2 interaction and increasing polymer–polymer interactions, resulting in higher cloud point pressure in SC-CO2 compared to PHFDA. On the other hand, the increase of the polymer–polymer interaction via π–π stacking provided an associative force to thicken SC-CO2. The subtle relationship between the copolymer composition and thickening abilities of the copolymers in SC-CO2 were evaluated and the optimum styrene molar ratio was determined. It can be concluded that the content of the CO2-philic HFDA groups and the CO2-phobic St groups in the copolymers should be optimized to achieve the balance between the solubility and the thickening capability.

Stimuli-responsive nanocomposite has a great potential application for cell imaging, drug delivery, and improving therapeutic effect. Rare-earth upconversion nanoparticles (UCNPs) have exhibited an excellent properties as a promising biological luminescent labels for fluorescence imaging. In this work, we prepared β-NaLuF4:Yb3+,Er3+ UCNPs coated with thermo-responsive copolymer poly(N-isopropyl acrylamide-co-acrylic acid) (P(NIPAM-co-AA)) by using ligand exchange strategy to obtain novel nanocomposite UCNP@P(NIPAM-co-AA). The acrylic acid moieties of P(NIPAM-co-AA) coordinate with the surfaces of UCNPs, and the PNIPAM moieties can induce the UCNPs dispersion or aggregation in the aqueous solution below and above the lower critical solution temperature (LCST) of PNIPAM. The UCNP@P(NIPAM-co-AA) exhibited weak upconversion luminescence(UCL) fluorescence intensity below the LCST but an 80-fold enhanced UCL intensity at 31 °C above their LCST with only 1 °C temperature transition range. The novel nanocomposite also shows a remarkable reversible property in aqueous solution and low cytotoxicity. For in vitro imaging, a 13-fold signal-to-noise ratio can be obtained below and above the LCST for the novel thermo-activatable UCL imaging, which implies potential application for intelligent biomedical agent.

The evaluation of the temperature–resistance performance of fracturing fluid is essential for choosing suitable fracturing fluids during fracturing treatment. In this work, related parameters for characterizing the temperature–resistance performance of fracturing fluids have been analysed systematically. The maximum temperature, Tmax(η0, t0), which satisfies both the minimum viscosity requirement (η ≥ η0) of fracturing fluid and the time requirement of fracturing treatment (t ≥ t0), was used to characterize the temperature–resistance performance of fracturing fluids. A facile procedure for evaluating Tmax(η0, t0) has been proposed based on a step-by-step numerical-search method. The search for Tmax(η0, t0) starts from the upper limit temperature Tmax, which is the maximum temperature where the apparent viscosity meets the minimum viscosity requirement, i.e., η ≥ η0. Using a borate cross-linked hydroxypropyl guar gum fracturing fluid as an example, the effects of pH, and the concentrations of thickening agent (hydroxypropyl guar, HPG) and crosslinking agent (Na2B4O7) on the crosslink and temperature–resistance properties are also investigated. It has been found that the crosslinking time tc decreases with the increase of HPG concentration or Na2B4O7 concentration. However, tc was found to increase when pH increases. The variation tendencies of Tmax(η0, t0) are different from that of Tmax, viz., Tmax(η0, t0) gradually increases with Na2B4O7 concentration, whereas Tmax increases significantly at low Na2B4O7 concentration and remains almost unchanged at high Na2B4O7 concentration. The possible mechanisms are proposed for interpreting the above phenomena according to related crosslinking-reaction kinetics and thermodynamics. Our work demonstrates a facile method for evaluating the temperature–resistance performance of the fracturing fluid and provides useful insights into the understanding of the temperature tolerance performance of the borate cross-linked hydroxypropyl guar gum fracturing fluid.

Surfactant-free α-Fe2O3 nanorings (NRs) were directly converted into water-dispersible Fe3O4 NRs through a simple and straightforward approach. In this process, uniform α-Fe2O3 NRs obtained through hydrothermal synthesis method are firstly thermally reduced to hydrophobic Fe3O4 NRs in the presence of hydrophobic oleic acid surfactant and non-polar trioctylamine solvent (under a flow of 5% H2/95% Ar). Subsequently, oxidative cleavage of oleic acid capping agent using sodium periodate oxidising agent is imparted to yield water-dispersible Fe3O4 NRs. As compared with the traditional solid-state reduction in tube furnace, the obtained Fe3O4 NRs using solution-based reduction process can retain its original uniform ring shape with good crystallinity and well-defined magnetic vortex domain. Moreover, with the presence of azelaic acid on the surface of hydrophilic Fe3O4 NRs, antibody or drugs can be easily conjugated, which further boost its potential theranostics application. This work provides a convenient approach to convert surfactant-free nanoparticle (NP) powders into water-dispersible NPs colloidal solutions for various biomedical applications.

Metastasis remains the major cause of death in cancer patients. Thus, there is a need to sensitively detect tumor metastasis, especially ultrasmall metastasis, for early diagnosis and precise treatment of cancer. Herein, an ultrasensitive T

Known for their capabilities in automated fluid manipulation, microfluidic devices integrated with pneumatic valves are broadly used for researches in life science and clinical practice. The application is, however, hindered by the high cost and overly complex fabrication procedure. Here, we present an approach for fabricating molds of active fluidic devices using a benchtop 3D printer and a simple 2-step protocol (i.e. 3D printing and polishing). The entire workflow can be completed within 6 h, costing less than US$ 5 to produce all necessary templates for PDMS replica molding, which have smooth surface and round-shaped pneumatic valve structures. Moreover, 3D printing can create unique bespoke on-off objects of a wide range of dimensions. The millimeter- and centimeter-sized features allow examination of large-scale biological samples. Our results demonstrate that the 3D-printed active fluidic device has valve control capacities on par with those made by photolithography. Controlled nutrients and ligands delivery by on-off active valves allows generation of dynamic signals mimicking the ever-changing environmental stimuli, and combinatorial/sequential drug inputs for therapeutic screening on liver tumor spheroid. We believe that the proposed methodology can pave the way for integration of active fluidic systems in research labs, clinical settings and even household appliances for a broad range of application.

Cancer metastasis is a serious concern and a major reason for treatment failure. Herein, we have reported the development of an effective and safe nanotherapeutic strategy that can eradicate primary tumors, inhibit metastasizing to lung, and control the metastasis and growth of distant tumors. Briefly, ferrimagnetic vortex-domain iron oxide nanoring (FVIO)-mediated mild magnetic hyperthermia caused calreticulin (CRT) expression on the 4T1 breast cancer cells. The CRT expression transmitted an "eat-me" signal and promoted phagocytic uptake of cancer cells by the immune system to induce an efficient immunogenic cell death, further leading to the macrophage polarization. This mild thermotherapy promoted 88% increase of CD8+ cytotoxic T lymphocyte infiltration in distant tumors and triggered immunotherapy by effectively sensitizing tumors to the PD-L1 checkpoint blockade. The percentage of CD8+ cytotoxic T lymphocytes can be further increased from 55.4% to 64.5% after combining with PD-L1 blockade. Moreover, the combination treatment also inhibited the immunosuppressive response of the tumor, evidenced by significant down-regulation of myeloid-derived suppressor cells (MDSCs). Our results revealed that the FVIO-mediated mild magnetic hyperthermia can activate the host immune systems and efficiently cooperate with PD-L1 blockade to inhibit the potential metastatic spreading as well as the growth of distant tumors.