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Core/shell nanocrystals (NCs) integrate collaborative functionalization that would trigger advanced properties, such as high energy conversion efficiency, nonblinking emission, and spin-orbit coupling. Such prospects are highly correlated with the crystal structure of individual constituents. However, it is challenging to achieve novel phases in core/shell NCs, generally non-existing in bulk counterparts. Here, we present a fast and clean high-pressure approach to fabricate heterostructured core/shell MnSe/MnS NCs with a new phase that does not occur in their bulk counterparts. We determine the new phase as an orthorhombic MnP structure (B31 phase), with close-packed zigzagged arrangements within unit cells. Encapsulation of the solid MnSe nanorod with an MnS shell allows us to identify two separate phase transitions with recognizable diffraction patterns under high pressure, where the heterointerface effect regulates the wurtzite → rocksalt → B31 phase transitions of the core. First-principles calculations indicate that the B31 phase is thermodynamically stable under high pressure and can survive under ambient conditions owing to the synergistic effect of subtle enthalpy differences and large surface energy in nanomaterials. The ability to retain the new phase may open up the opportunity for future manipulation of electronic and magnetic properties in heterostructured nanostructures.

The fragments from crushed rock are initially very angular. The erosion process causes the fragment shape to evolve from angular to well rounded and affects the mechanical behaviour of granular materials. This report explores the effect of particle shape caused by erosion (Er) on macroscopic and microscopic behaviour under triaxial compression tests of granular materials via the discrete element method. A convex rigid block was employed to model particles with different erosion degrees. After being prepared in the densest condition, all particle assemblies were subjected to axial compression until a critical state was reached. The macroscopic characteristics, including the shear strength and dilatancy response, were investigated. As Er increased, the shear strength generally decreased, and the volumetric strain monotonically decreased. Then, the microscopic characteristics, including the coordination number, particle rotation, percentage of sliding contacts and contact force, were examined. Finally, analysis-related anisotropy coefficients of the entire contact network were evaluated to probe the microscopic origins of the peak and residual shear strength related to Er.

Horizontal well multistage fracturing technology is a high-efficiency method for tight oil and gas production, which increases the contact area between the wellbore and stratum by forming multiple transverse hydraulic fractures (HFs). The stress interference caused by the created HFs will affect the propagation geometries of the subsequent HFs, and then affect the overall fracturing treatment performance. In order to study the distribution of HFs and law of interference among multiple fractures during horizontal well multistage fracturing in tight reservoirs, in this paper, the effects of horizontal stress difference, perforation spacing, and net pressure in the created fracture on the initiation and propagation of multiple cracks were specially studied through large-scale hydraulic fracturing experiments and numerical simulation. The results showed that under high horizontal stress difference, multiple HFs with small spacing tended to coalesce at a place where the length has extended to a certain level. It was also found that the initiation pressures of HFs within subsequent stages increase with the rise of net pressure in created HFs, which causes the subsequent fractures to deviate from the direction perpendicular to the horizontal wellbore and then to gradually deflect toward it. Moreover, the ratio of fracture spacing to fracture height, and the net pressure are the key parameters to determine the deflection degree of HFs for multistage fracturing. In addition, the deflection degree of subsequent HFs was expected to enhance with the decreasing ratio of fracture spacing to fracture height and increasing net pressure in created HFs. It was useful for mitigating stress interference to lengthen the stage spacing, control the fracture height, and reduce the net pressure. The research results have a reference value for the optimal design of the fracture spacing for multistage fracturing.

Rationale: Nanoscale vehicles responsive to abnormal variation in tumor environment are promising for use in targeted delivery of therapeutic drugs specifically to tumor sites. Herein, we report the design and fabrication of self-accelerating H2O2-responsive plasmonic gold nanovesicles (GVs) encapsulated with tirapazamine (TPZ) and glucose oxidase (GOx) for synergistic chemo/starving therapy of cancers. Methods: Gold nanoparticles were modified with H2O2-responsive amphiphilic block copolymer PEG45-b-PABE330 by ligand exchange. The TPZ and GOx loaded GVs (TG-GVs) were prepared through the self-assembly of PEG45-b-PABE330 -grafted nanoparticles together with TPZ and GOx by solvent displacement method. Results: In response to H2O2 in tumor, the TG-GVs dissociate to release the payloads that are, otherwise, retained inside the vesicles for days without noticeable leakage. The released GOx enzymes catalyze the oxidation of glucose by oxygen in the tumor tissue to enhance the degree of hypoxia that subsequently triggers the reduction of hypoxia-activated pro-drug TPZ into highly toxic free radicals. The H2O2 generated in the GOx-catalyzed reaction also accelerate the dissociation of vesicles and hence the release rate of the cargoes in tumors. The drug-loaded GVs exhibit superior tumor inhibition efficacy in 4T1 tumor-bearing mice owing to the synergistic effect of chemo/starvation therapy, in addition to their use as contrast agents for computed tomography imaging of tumors. Conclusion: This nanoplatform may find application in managing tumors deeply trapped in viscera or other important tissues that are not compatible with external stimulus (e.g. light).

Rock joint shape characteristics, waviness and unevenness play essential but distinct roles in shear mechanism of rock joints. This study presents a novel method to generate virtual rock joint profiles with realistic waviness and unevenness features. Firstly, joint profiles are obtained by 3D laser scanning device. Secondly, quantification of waviness and unevenness is conducted by traditional method, including digital filtering technique and roughness parameter RL. Thirdly, the discrete Fourier transform (DFT) method is employed to analyze the joint outlines. Two representative Fourier shape descriptors (D3, D8) for characterization of waviness and unevenness are suggested. Then, the inverse discrete Fourier transform (IDFT) is adopted to reconstruct the joint profiles with random values of phase angles but prescribed amplitudes controlled by D3 and D8. The traditional method is then applied to the reconstructed joint profiles to examine statistically the relationships between D3 and D8 and parameters RL of waviness and unevenness, respectively. The results show that larger D8 tends to result in larger waviness while higher D3 tends to increase unevenness. Reference charts for estimation of waviness and unevenness with different pairs of D3 and D8 are also provided to facilitate implementation of random joint reconstruction.

Core/shell nanocrystals (NCs) integrate collaborative functionalization that would trigger advanced properties, such as high energy conversion efficiency, nonblinking emission, and spin–orbit coupling. Such prospects are highly correlated with the crystal structure of individual constituents. However, it is challenging to achieve novel phases in core/shell NCs, generally non-existing in bulk counterparts. Here, we present a fast and clean high-pressure approach to fabricate heterostructured core/shell MnSe/MnS NCs with a new phase that does not occur in their bulk counterparts. We determine the new phase as an orthorhombic MnP structure (B31 phase), with close-packed zigzagged arrangements within unit cells. Encapsulation of the solid MnSe nanorod with an MnS shell allows us to identify two separate phase transitions with recognizable diffraction patterns under high pressure, where the heterointerface effect regulates the wurtzite → rocksalt → B31 phase transitions of the core. First-principles calculations indicate that the B31 phase is thermodynamically stable under high pressure and can survive under ambient conditions owing to the synergistic effect of subtle enthalpy differences and large surface energy in nanomaterials. The ability to retain the new phase may open up the opportunity for future manipulation of electronic and magnetic properties in heterostructured nanostructures., Core/shell MnSe/MnS nanocrystals with the B31 phase are thermodynamically stable under high pressure and can survive under ambient conditions owing to the synergistic effect of subtle enthalpy differences and high surface energy in nanomaterials.

This letter examines the effect of fines content on the small-strain stiffness (G0) of gap-graded soils via the discrete element method (DEM). The G0 values were obtained by DEM simulations of drained triaxial tests. Microscopic analysis reveals that the G0 uniquely depends on the mechanical coordination number (CN) of the soils. Furthermore, modified CNs that consider coarse-coarse, coarse-fine and fine-fine contact in the sample are quantified, partially reflecting the contribution of each contact type to G0. The results indicate that as fines content increases, the fines begin to participate in the force chains and their contribution to G0 should be considered.

模板法是可控合成复合纳米材料的一种重要手段. 然而, 纳米材料在模板, 尤其是复合模板上的选择性生长仍面临巨大挑战. 本文以自组装聚乙烯-金纳米颗粒一维复合纳米链为软-硬复合模板, 实现金属在该模板上可控地选择性沉积、生长. 通过选择恰当的表面活性剂来调节金属生长的热力学, 金属可以选择性地生长在金纳米颗粒的表面, 得到金属间歇包覆的复合纳米链; 也可以同时包覆在聚乙烯和金纳米颗粒的表面, 得到金属完全包覆的豌豆荚状复合纳米链. 不同的包覆方式和包覆材料选择都会导致材料光学性质的变化. 时间差分有限元模拟表明, 金包覆的豌豆荚状复合纳米链的表面金壳层和内部金纳米颗粒之间存在极强的表面等离子体耦合作用. 在表面增强拉曼实验中, 该复合纳米链表现出很强的增强信号.

This report explores the effects of particle shape and content of fines on the shear behavior of sand-fines mixtures using a two-dimensional discrete element method. The contributions of different contact types to the residual shear strength are quantified. Microscopic analysis of each contact type, including coordination number, normal contact force and their contributions to the principal stress components, reveals why the contribution of each contact type to the residual shear strength is varied. Finally, anisotropic analysis enables us to understand the microscopic mechanisms that cause the residual shear strength to be dependent on the particle shape and content of fines.

How to fabricate scale low-cost microfluidic device for detection of biomarkers owns a great requirement. Herein, it is for the first time reported that a new microfluidic device based on bonding polydimethylsiloxane microfluidic channels onto the substrate of a screen-printed electrode with coating glass solution was fabricated for electrochemical sensing of prostate-specific antigen (PSA). Compared to traditional microfabrication processes, this method is simple, fast, low cost, and also suitable for mass production. The prepared screen-printed electrode-based microfluidic device (CASPE-MFD) was used for the detection of the PSA in human serum. The prepared CASPE-MFD had a detection limit of 0.84 pg/mL (25.8 fM) and a good linearity with PSA concentration ranging from 0.001 to 10 ng/mL, which showed a great promise platform toward the development of miniaturized, low-cost electrochemical microfluidic device for use in human health, environmental monitoring, and other applications. Electronic supplementary material The online version of this article (10.1186/s11671-019-2857-6) contains supplementary material, which is available to authorized users.

Melamine, which induces proximal tubular (PT) cell damage has a greater nephrotoxic effect when combined with cyanuric and uric acids; however, it is unknown whether such effect can stimulate calcium phosphate (CaP)/calcium oxalate (CaOx) stone formation. Here, we show that melamine acts as an inducer of CaP, CaOx and CaP + CaOx (mixed) crystal formations in a time and concentration-dependent manner by stabilizing those crystals and further co-aggregating with melamine. To explore the physiological relevance of such melamine-augmented calcium crystal formation, we used 2-dimensional (2D) and 3D microfluidic (MF) device, embedded with PT cells, which also resembled the effect of melamine-stimulated CaP, CaOx and mixed crystal formation. Significantly, addition of preformed CaP and/or CaOx crystal in the presence of melamine, further potentiated those crystal formations in 3D MFs, which helped the growth and aggregation of mixed crystals. Our data show that the mechanism of such predisposition of stone formation could be largely due to co-crystallization between melamine and CaP/CaOx and pronounced effect on induction of stone-forming pathway activation in 3D MF. Taken together, melamine-induced CaP and/or CaOx crystal formation ex-vivo will help us in understanding the larger role of melamine as an environmental toxicant in producing the pathology in similar cellular microenvironments.

OBJECTIVES: A nanoparticle-doped adhesive that can be controlled with magnetic forces was recently developed to deliver drugs to the pulp and improve adhesive penetration into dentin. However, it did not have bactericidal and remineralization abilities. The objectives of this study were to: (1) develop a magnetic nanoparticle-containing adhesive with dimethylaminohexadecyl methacrylate (DMAHDM), amorphous calcium phosphate nanoparticles (NACP) and magnetic nanoparticles (MNP); and (2) investigate the effects on dentin bond strength, calcium (Ca) and phosphate (P) ion release and anti-biofilm properties. METHODS: MNP, DMAHDM and NACP were mixed into Scotchbond SBMP at 2%, 5% and 20% by mass, respectively. Two types of magnetic nanoparticles were used: acrylate-functionalized iron nanoparticles (AINPs); and iron oxide nanoparticles (IONPs). Each type was added into the resin at 1% by mass. Dentin bonding was performed with a magnetic force application for 3 minutes, provided by a commercial cube-shaped magnet. Dentin shear bond strengths were measured. Streptococcus mutans biofilms were grown on resins, and metabolic activity, lactic acid and colony-forming units (CFU) were determined. Ca and P ion concentrations in, and pH of biofilm culture medium were measured. RESULTS: Magnetic nanoparticle-containing adhesive using magnetic force increased the dentin shear bond strength by 59% over SBMP Control (p < 0.05). Adding DMAHDM and NACP did not adversely affect the dentin bond strength (p > 0.05). The adhesive with MNP+DMAHDM+NACP reduced the Streptococcus mutans biofilm CFU by 4 logs. For the adhesive with NACP, the biofilm medium became a Ca and P ion reservoir. The biofilm culture medium of the magnetic nanoparticle-containing adhesive with NACP had a safe pH of 6.9, while the biofilm medium of commercial adhesive had a cariogenic pH of 4.5. CONCLUSIONS: Magnetic nanoparticle-containing adhesive with DMAHDM and NACP under a magnetic force yielded much greater dentin bond strength than commercial control. The novel adhesive reduced biofilm CFU by 4 logs and increased the biofilm pH from a cariogenic pH 4.5 to 6.9, and therefore is promising to enhance the resin-tooth bond, strengthen tooth structures, and suppress secondary caries at the restoration margins.

The discrete element method (DEM) represents a classical and popular research approach to exploring the particle shape effects of granular materials. For many modellers, the acquisition of irregular particle outlines is a problem of considerable practical importance. To mitigate this problem, a novel method based on epicycle series is introduced in this study, and it can produce geometry-controlled particles from two major shape indexes. First, the three key steps of the proposed method are explained: (1) a series of complex numbers, namely, the epicycle series, is used to represent the discrete outline of a particle; (2) the magnitudes of the epicycle descriptors are correlated with the particle shape indexes; and (3) the particle shape is controlled by predicting and adjusting the epicycle descriptors. Then, sensitivity analysis and a case study are conducted to test the proposed method's capacity for reproducing particle shape features. The results suggest that the proposed framework can generate granular particles with accurately controlled shape indexes and realistic outlines, which can facilitate the DEM modelling of irregular particles.

Colloidal liquid crystals (LCs) are an emerging class of soft materials that naturally combine the unique properties of both LC molecules and colloidal particles. Chiral LC blue phases are highly attractive in fast optical displays and electrooptical devices, but the formation of chiral structures from achiral colloidal particles is rare. Herein we demonstrate that achiral dumbbell-shaped colloids can assemble into a rich variety of characteristic LC phases, including nematic phases with lock structures, smectic phases, and particularly double-twisted chiral columnar phases. Phase diagrams from experiments and simulations show that the existence and stable regions of different LC phases are strongly dependent on the geometry of colloids. Furthermore, the LC phases can be dynamically tuned by external magnetic fields. This work paves a new route to the development of stimuli-responsive functional LC mesostructures for LC display and laser applications.

Colloidal liquid crystals are an emerging class of soft materials that naturally combine the unique properties of both liquid crystal molecules and colloidal particles. Chiral liquid crystal blue phases are attractive for use in fast optical displays and electrooptical devices, but the construction of blue phases is limited to a few chiral building blocks and the formation of blue phases from achiral ones is often counterintuitive. Herein we demonstrate that achiral dumbbell-shaped colloids can assemble into a rich variety of characteristic liquid crystal phases, including nematic phases with lock structures, smectic phase, and particularly experimental observation of blue phase III with double-twisted chiral columns. Phase diagrams from experiments and simulations show that the existence and stable regions of different liquid crystal phases are strongly dependent on the geometrical parameters of dumbbell-shaped colloids. This work paves a new route to the design and construction of blue phases for photonic applications.

Self-assembly of giant building blocks beyond conventional molecules offers tremendous opportunities for the fabrication of new-generation structural materials. This work describes the macroscopic colloidal segregation in the vesicular self-assembly of binary nanoparticle amphiphiles (NPAMs) consisting of block copolymer-grafted nanoparticles in solution. Depending on their relative size and concentration, binary NPAMs with distinctive sizes assemble into hybrid vesicles with different morphologies, namely, homogeneous vesicles, patchy vesicles, and yolk/shell vesicles. The segregation of NPAMs confined within or escaped from the vesicular membrane is driven by the conformational entropy gain of end-grafted copolymer ligands. The effect of NPAM size and concentration on the morphological transition of vesicles is mapped in a phase diagram. Moreover, a vesicular fusion/budding mechanism is proposed to illustrate the formation of uniform vesicles with yolks inside. The hybrid vesicles have potential applications in cancer imaging, biosensing, and drug delivery.

Existing DEM researches related to particle breakage usually assume that particles are regular shapes and debris is spherical. In this paper, a method combining relatively realistic particle shape and realistic breakage is proposed to study particle breakage in the DEM. The particle morphology was derived from the scanned real particles and was convex treated. The breakable particle was modelled as an aggregate composed with coplanar and glued Voronoi polyhedra. Then, a series of drained triaxial tests under different confining pressures were conducted. The macroscopic characteristics, including the shear strength, dilatancy and particle breakage, are qualitatively in agreement with previous literatures, which show the rationality of the proposed method. Further, the microscopic characteristics, including the coordination number and sliding contact, were investigated to explore the effect of particle breakage on the macroscopic shear behaviour. Finally, the analysis-related anisotropy coefficients were evaluated to probe the microscopic origins of the peak and critical shear strengths.

Nanoparticle (NP)‐based vehicles are attractive for biomedical delivery and therapy, owing to improved therapeutic efficiency and reduced adverse effects compared to free drugs. Uncontrolled NP heterogeneity at the suspension level or single particle level poses grand challenges in the effective use of NPs for biology and medicines. Precision nanoparticles (PNPs) are a class of discrete nanostructures exhibiting elaborately tailored surface or structural heterogeneity, but minimal variations between nanostructures in one solution. Benefiting from their precisely controlled NP heterogeneity, PNPs have emerged as promising platforms for modulating various biological processes to improve the biomedical performance of NP‐based vehicles. This review summarizes recent advances in the development of precisely tailored PNPs for biomedical applications, with an emphasis on the nano‐bio interactions, and drug delivery and therapy. We start with a brief overview of the major categories of PNPs and their fabrication strategies (section 2). We then focus on reviewing the use of PNPs for enhancing biomolecular recognition or detection, regulating the NP‐protein interactions, modulating the NP‐biomembrane interactions, and improving the biological delivery and therapy (section 3). Finally, we discuss the challenges and perspectives on the design and use of PNPs for biomedical applications (section 4).

In this communication, we report a composite macroporous hydrogel sheet that can rapidly transform into multiple 3D shapes in response to near-infrared (NIR) light on demand. The transformation relies on the photo-thermal-induced asymmetric shrinking of the hydrogel material, which is further verified by finite element modeling.

Magneto-plasmonic Janus vesicles (JVs) integrated with gold nanoparticles (AuNPs) and magnetic NPs (MNPs) were prepared asymmetrically in the membrane for in vivo cancer imaging. The hybrid JVs were produced by coassembling a mixture of hydrophobic MNPs, free amphiphilic block copolymers (BCPs), and AuNPs tethered with amphiphilic BCPs. Depending on the size and content of NPs, the JVs acquired spherical or hemispherical shapes. Among them, hemispherical JVs containing 50 nm AuNPs and 15 nm MNPs showed a strong absorption in the near-infrared (NIR) window and enhanced the transverse relaxation (T2) contrast effect, as a result of the ordering and dense packing of AuNPs and MNPs in the membrane. The magneto-plasmonic JVs were used as drug delivery vehicles, from which the release of a payload can be triggered by NIR light and the release rate can be modulated by a magnetic field. Moreover, the JVs were applied as imaging agents for in vivo bimodal photoacoustic (PA) and magnetic resonance (MR) imaging of tumors by intravenous injection. With an external magnetic field, the accumulation of the JVs in tumors was significantly increased, leading to a signal enhancement of approximately 2–3 times in the PA and MR imaging, compared with control groups without a magnetic field.

We present a new paradigm for designing responsive hydrogel sheets that can exhibit ultrafast snapping deformation., The design of materials that can mimic the complex yet fast actuation phenomena in nature is important but challenging. Herein, we present a new paradigm for designing responsive hydrogel sheets that can exhibit ultrafast inverse snapping deformation. Dual-gradient structures of hydrogel sheets enable the accumulation of elastic energy in hydrogels by converting prestored energy and rapid reverse snapping (

This report investigates the effects of Fourier-based particle shape on the macroscopic and microscopic shear responses of rockfill material via a series of numerical biaxial compression tests. The multi-disk method is employed to model two-dimensional irregular rockfill particles. The macroscopic characteristics, including the shear strength and the dilatancy response, and the microscopic characteristics, including the contact force, the coordination number and the sliding contact, are examined. Then, detailed analyses of the fabric anisotropy of the entire contact network empower us to understand the microscopic mechanisms that lead to the dependency of the shear strength on particle shape. Subsequently, analyses concerning the fabric anisotropy of the strong and weak contact networks are carried out. It is found that the macroscopic stress ratio exhibits a linear pattern with the anisotropic coefficient of contacts in the strong contact network, and that the slope depends on particle shape.

Plasmonic metal nanoparticles have unique optical properties, such as localized surface plasmon resonance resulting from the oscillation of free electrons. Integrating discrete plasmonic nanoparticle into assembled nanostructures enables interparticle plasmon coupling and collective properties that are often absent in their discrete counterparts. Synthetic polymers as surface ligands on plasmonic nanoparticles can stabilize the nanoparticles, define the surface properties, control the interparticle interactions and therefore direct the nanoparticle self-assembly. Given the length scale of polymers comparable to the size of plasmonic nanoparticles of interest, polymer ligands are promising for precisely controlling the interparticle interaction. Engineering polymer ligands in the terms of their chemical composition, grafting density, anchoring groups and chain lengths is critical to control the assembly nanostructures and plasmon coupling of adjacent nanoparticles. The focus of this perspective is to identify and address the unmet challenges in the field of polymer-grafted plasmonic nanoparticles (PGNPs). Key unresolved issues broadly covered from the design of PGNP building blocks to their self-assembly are illustrated by highlighting a few examples. In views of more robust building blocks, the choice of inexpensive metals, the new anchoring groups and precision control of polymer ligands are discussed. We further consider the challenges in breaking the surface symmetry of plasmonic nanoparticles and designing synthetic polymers to achieve reversibility and directionality in the self-assembly of PGNPs.

Diabetic patients have a higher risk of colorectal cancer (CRC). The role of metformin in CRC incidence among type 2 diabetes mellitus (T2DM) remains controversial.A meta-analysis was performed to evaluate the role of metformin treatment in the occurrence of CRC among T2DM patients.Search was performed throughout PubMed, Embase, Springer databases up to November 2014. The search terms were (biguanides or metformin) and (bowel or colon or rectal or colorectal) and (cancer or neoplasm or neoplasia). Relative risk (RR) and 95% confidence interval (CI) was pooled using random-effects model or fixed-effect model basing on heterogeneity, which was calculated basing on Q statistics and χA total of 11 studies, including eight cohort studies and three case-control studies, were enrolled in the meta-analysis. Obvious heterogeneity was noted, and a 25% lower CRC incidence was found among diabetic patients treated with metformin (pooled RR=0.75, 95% CI: 0.66-0.86), using the random-effects model. Subgroup analyses showed that CRC incidence significantly reduced among T2DM in different regions, non-metformin treatment and cohort studies. Evidence supported significant publication for studies investigating from Egger's regression test. Conversely, no missing data were found using trim and fill analysis.In conclusion, the meta-analysis suggests metformin may reduce CRC incidence among diabetics, which is useful medical information for clinicians.

The stepwise self-assembly of hollow plasmonic vesicles with vesicular membranes containing strings of gold nanoparticles (NPs) is reported. The formation of chain vesicles can be controlled by tuning the density of the polymer ligands on the surface of the gold NPs. The strong absorption of the chain vesicles in the near-infrared (NIR) region leads to a much higher efficiency in photoacoustic (PA) imaging than for non-chain vesicles. The chain vesicles were further employed for the encapsulation of drugs and the NIR light triggered release of payloads. This work not only offers a new platform for controlling the hierarchical self-assembly of NPs, but also demonstrates that the physical properties of the materials can be tailored by controlling the spatial arrangement of NPs within assemblies to achieve a better performance in biomedical applications.

There is a high demand on a simple, rapid, accurate, user-friendly, cost-effective, and nondestructive universal method for latent finger-print (LFP) detection. Herein, we describe a combination imaging strategy for LFP visualization with high resolution using poly(styrene-alt-maleic anhydride)-b-polystyrene (PSMA-b-PS) functionalized gold nanoparticles (GNPs). This general approach integrates the merits of both colorimetric imaging and photoacoustic imaging. In comparison with the previous methods, our strategy is single-step and does not require the signal amplification by silver staining. The PSMA-b-PS functionalized GNPs have good stability, tunable color, and high affinity for universal secretions (proteins/polypeptides/amino acids), which makes our approach general and flexible for visualizing LFPs on different substrates (presumably with different colors) and from different people. Moreover, the unique optical property of GNPs enables the photoacoustic imaging of GNPs-deposited LFPs with high resolution. This allows observation of level 3 hyperfine features of LFPs such as the pores and ridge contours by photoacoustic imaging. This technique can potentially be used to identify chemicals within LFP residues. We believe that this dual-modality imaging of LFPs will find widespread use in forensic investigations and medical diagnostics.

This report investigated the effects of irregular particles on macroscopic and microscopic behaviour under triaxial compression tests for a range of various roundnesses. A multi-sphere method was employed to model the three-dimensional irregular particles generated by rotation-invariant spherical harmonics. After being prepared in the densest conditions, all assemblies were subjected to axial compression until a critical state was reached. The macroscopic characteristics, including the shear strength and dilatancy response, were investigated. We found that the shear strength generally decreased and the volumetric strain linearly and monotonically decreased with increasing roundness. Then, the microscopic characteristics, including the coordination number, particle rotation and percentage of sliding contacts, were examined. An increase in the coordination number obstructed the rotation of particles and led to an increase in the percentage of sliding contacts. Finally, analysis of the related anisotropy coefficients of the entire contact network was carried out to probe the microscopic origins of macroscopic behaviour. A detailed analysis revealed the microscopic mechanism of the dependence of the peak and residual shear strengths on roundness.

Biomimetic synthesis is a promising strategy for the preparation of nanotheranostics with excellent biocompatibility. Herein, we report a biomimetic approach to synthesize folic acid (FA) modified copper sulfide (CuS) nanodots for cancer phototheranostics by using melanin as a biotemplate and FA as a stabilizer. Owing to the high affinity of melanin for metal ions, copper ions can be adsorbed on the surface of melanin and then reacted with S2− ions to form CuS nanodots. As a natural biomolecule, melanin has high biocompatibility and biodegradability, which can effectively improve the biosafety of the prepared CuS nanodots. More importantly, both melanin and CuS have strong near-infrared (NIR) absorption, the as-prepared CuS-Melanin-FA composite nanoprobes with high photothermal conversion efficiency are promising for augmented photoacoustic imaging and photothermal therapy of cancer, which is demonstrated on 4T1 tumor-bearing mice. Moreover, the biomimetic synthesis method for the preparation of CuS nanodots opens a new horizon for the biomimetic synthesis of other nanotheranostics.

This article describes a nanoplatform based on matrix metalloproteinase (MMP)-responsive gold nanoparticles (AuNPs) for tumor-targeted photoacoustic (PA) imaging-guided photothermal therapy and drug delivery. AuNPs were grafted with complementary DNA strands, tethered with doxorubicin and coated with poly(ethylene glycol) via a thermal-labile linker and a MMP-cleavable peptide, respectively. The nanoprobes remained well-isolated in healthy tissues, but formed aggregates rapidly under MMP-abundant conditions. The DNA hybridization-induced assembly of the nanoprobes led to prolonged tumor retention and strong near-infrared (NIR) absorption, which is beneficial to deep-tissue imaging and therapy. Compared with MMP-inert nanoprobes, our platform demonstrated significantly enhanced efficiency in PA imaging and photothermal conversion upon NIR irradiation. Meanwhile, doxorubicin could be released rapidly in response to the localized elevation of temperature, leading to synergistic chemo-photothermal therapy. The unique nanoplatform may find applications in effective disease control by delivering imaging and therapy to tumors with high specificity, safety, and universality.