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The diagnosis of gastrointestinal (GI) tract diseases is frequently performed in the clinic, so it is crucial to develop high-performance contrast agents for real-time and non-invasive imaging examination of the GI tract. Herein, we show a novel method to synthesize a neodymium (Nd) chelate, Nd-diethylenetriaminepentaacetic acid (Nd-DTPA), on a large scale without byproducts for spectral computed tomography (CT) and second near-infrared window imaging of the GI tract in vivo. The Nd-DTPA was simply generated by heating the mixture of Nd2O3 and DTPA in water at 85 °C for 2 h. This dual-modal imaging agent has the advantages of a simple and green synthesis route, no need of purification process, high yield (86.24%), large-scale production capability (>10 g in lab synthesis), good chemical stability and excellent water solubility (≈2 g mL−1). Moreover, the Nd-DTPA emitted strong near-infrared fluorescence at 1308 nm, and exhibited superior X-ray attenuation ability compared to clinical iohexol. The proposed Nd-DTPA can integrate the complementary merits of dual-modal imaging to realize spatial-temporal and highly sensitive imaging of the GI tract in vivo, and accurate diagnosis of the location of intestinal obstruction and monitor its recovery after surgery. The developed highly efficient method for the gram-scale synthesis of Nd-DTPA and the proposed spectral CT and second near-infrared window dual-modal imaging strategy provide a promising route for accurate visualization of the GI tract in vivo. [ABSTRACT FROM AUTHOR]

A novel expanded metal–organic framework (UTSA-111a) with functional pyrimidine sites exhibits simultaneously high gravimetric and volumetric methane storage working capacities of 309 cm3 (STP) g−1 and 183 cm3 (STP) cm−3 at 298 K and 5.8–65 bar. [ABSTRACT FROM AUTHOR]

Realization of ethane-trapping materials for separating ethane (C2H6) from ethylene (C2H4) by adsorption, to potentially replace the energy-intensive cryogenic distillation technology, is of prime importance in the petrochemical industry. It is still very challenging to target C2H6-selective adsorbents with both high C2H6 capture capacity and gas selectivity. Herein, we report that a crystal engineering or reticular chemistry strategy enables the control of pore size and functionality in a family of isomorphic metal–organic frameworks (MOFs) for boosting the C2H6 uptake and selectivity simultaneously. By altering the carboxylic acid linker in Ni(bdc)(ted)0.5, we developed two novel isoreticular MOFs, Ni(ndc)(ted)0.5 and Ni(adc)(ted)0.5 (termed ZJU-120 and ZJU-121, respectively), in which the pore sizes and nonpolar aromatic rings can be finely engineered. We discover that activated ZJU-120a with the optimized pore size (4.4 Å) and aromatic rings exhibits both a very high C2H6 uptake (96 cm3 g−1 at 0.5 bar and 296 K) and C2H6/C2H4 selectivity (2.74), outperforming most of the C2H6-selective MOFs reported. Computational studies indicate that the suitable pore size and more nonpolar aromatic rings on the pore surfaces of ZJU-120a mainly contribute to its exceptional C2H6 uptake and selectivity. The breakthrough experiments demonstrate that ZJU-120a can efficiently separate C2H6 from 50/50 and 10/90C2H6/C2H4 mixtures under ambient conditions. [ABSTRACT FROM AUTHOR]

We realized that tailoring the pore size/geometry and chemistry, by virtue of alkynyl or naphthalene replacing phenyl within a series of isomorphic MOFs, can optimize methane storage working capacities, affording an exceptionally high working capacity of 203 cm3 (STP) cm−3 at 298 K and 5–80 bar. [ABSTRACT FROM AUTHOR]

Paraquat (PQ), a broad-spectrum contact herbicide, has been used in many countries for controlling weed growth in agriculture because of its quick-acting and nonselective contact with green plant tissue. PQ is also toxic to humans, and even contributes to the development of neurodegenerative diseases. However, PQ is generally excluded from pesticide residue monitoring programs due to the lack of suitable determination methods. Thus, this study developed a detection method combined with simple extraction and surface-enhanced Raman spectroscopy (SERS) to rapidly determine and quantify the PQ residue on legumes without destructive procedures and high-cost instruments. Following the extraction procedure of the QuPPe-method, however, we took whole adzuki beans (Vigna angularis) extracted via a mixture of methanol and 1% formic acid at room temperature and followed by a 1 min cleanup by SPE. The PQ values for adzuki beans determined by LC/MSMS showed that regardless of whether extraction was followed by the QuPPe-method or the method we proposed, a consistent and low relative standard deviation (RSD) below ＜22% was found. In this study, we proposed to extract PQ on the surface of the beans by shaking briefly with solvent, and then the PQ molecules were detected and quantified by depositing Ag nanoparticles (AgNPs) and performing SERS within 10 min. Using a coating of deposited Ag nanoparticles, SERS can achieve a limit of detection (LOD) for PQ on the order of 1 μg L−1 (∼4 × 10−9 M) and a method detection limit (MDL) for adzuki beans of 0.8 μg kg−1 (∼3.3 × 10−9 M). This sensitivity at the ppb level absolutely met the maximum residue limit (MRL) for PQ in dried beans as declared by most countries, including the US (0.3 mg kg−1), Australia (1.0 mg kg−1) and Taiwan (0.2 mg kg−1). Taiwan will ban the use of PQ as a defoliating agent for harvest in adzuki bean fields in 2019; therefore, developing a method for detecting PQ residues in the field or in import markets is necessary for consumer health and for authorities. This study provided an opportunity to utilize SERS in the field of on-site pesticide residue screening. [ABSTRACT FROM AUTHOR]

Near-infrared (NIR) emission and two-photon excited fluorescence (TPEF) are both desirable features for bioimaging because they offer several advantages, such as deep tissue penetration, high spatial resolution and low background noise. However, incorporation of NIR emission and TPEF into the same labeling dye molecule remains a formidable challenge as it requires three features simultaneously: large two-photon absorption cross-section (δ), high fluorescence quantum yield (Φ) and an appropriate NIR absorption/emission wavelength. Herein, we report a theory-assisted design of novel benzoindolic squaraine (BIS) dye molecules that exhibit a high-performance NIR emission and TPEF properties simultaneously. First, the planarity of the BIS core extended the π-framework, which leads to NIR emission at 682 nm with a quantum yield greater than 40%. Second, we utilized the local electric field effect by the addition of non-conjugated D/A moieties to the BIS core to modulate the two-photon absorption (TPA) cross-section (δ) values. Natural transition orbital calculations suggest that non-conjugated D or A groups do not affect the one-photon photophysical properties of BIS dyes, but can alter the molecular orbitals involved in the Sn← S0 (n≥ 2) TPA process. With this new strategy, we successfully obtained a methoxyl-modified molecule (BIS-1), which presents a TPA window between 780 and 950 nm, with the largest δ value above 12 000 GM. [ABSTRACT FROM AUTHOR]

Clinical diagnosis of malignant tumors using nanoprobes needs severe improvements in the aspects of sensitivity and biocompatibility. Integrating a dual-targeting strategy with the selection of human-inherent elements and molecules as raw materials shows great potential in the development of a biosafe and sensitive nanoplatform. To carry out the proposed design, we constructed a biocompatible, dual-targeting MR imaging nanoprobe, based on Fe3O4 nanoparticles (NPs) co-modified with inherently innoxious hyaluronic acid (HA) and transferrin (Tf). HA was used as both a template and a targeting molecule to form Fe3O4@HA NPs through a one-step co-precipitation method, which were then further modified with Tf to obtain the dual-targeting Fe3O4@HA@Tf NPs at room temperature. The excellent biocompatibility of the nanoprobe was demonstrated via toxicity assays in vitro and in vivo. The desirable dual-targeting ability towards tumor cells was confirmed by a cellular uptake test (Hela cells, overexpressing both CD44 and transferrin receptors), and the developed nanoprobe was successfully applied in tumor-targeted MR imaging in vivo. In summation, we developed a dual-targeting Fe3O4 nanoprobe, following a facile procedure at room temperature. The nanoprobe showed a high targeting ability towards tumor cells and excellent biocompatibility, which showed its great potential to be applied in the clinical diagnosis of tumors. [ABSTRACT FROM AUTHOR]

Photothermal therapy as a physical therapeutic approach has greatly attracted research interest due to its negligible systemic effects. Among the various photothermal agents, CuS nanoparticles have been widely used due to their easy preparation, low cost, high stability and strong absorption in the NIR region. However, the ambiguous biotoxicity of CuS nanoparticles limited their bio-application. So it is highly desirable to develop biocompatible CuS photothermal agents with the potential of clinical translation. Herein, we report a novel method to synthesize biocompatible CuS nanoparticles for photothermal therapy using bovine serum albumin (BSA) as a template via mimicking biomaterialization processes. Owing to the inherent biocompatibility of BSA, the toxicity assays in vitro and in vivo showed that BSA–CuS nanoparticles possessed good biocompatibility. In vitro and in vivo photothermal therapies were performed and good results were obtained. The bulk of the HeLa cells treated with BSA–CuS nanoparticles under laser irradiation (808 nm) were killed, and the tumor tissues of mice were also successfully eliminated without causing any obvious systemic damage. In summary, a novel strategy for the synthesis of CuS nanoparticles was developed using BSA as the template, and the excellent biocompatibility and efficient photothermal therapy effects of BSA–CuS nanoparticles show great potential as an ideal photothermal agent for cancer treatment. [ABSTRACT FROM AUTHOR]

Owing to the biological and clinical significance of deoxyribonuclease I (DNase I), it is highly desirable to develop near-infrared (NIR) fluorescent assays for the determination of DNase I activity. Here we report a label-free NIR fluorescent assay for selective determination of DNase I activity based on malachite green (MG)/G-quadruplexes. In the presence of Na+ or K+, single stranded DNA (ssDNA) is able to form a G-quadruplex structure, thus to increase the rigidity of MG structure and result in a remarkable NIR fluorescence. As DNase I is capable of cleaving all types of DNA indiscriminately to release nucleotide products, the G-quadruplexes are cleaved into oligonucleotides in the presence of DNase I. As a result, the rigidity of MG structure is reduced, and the NIR fluorescence of the solution decreases with increase of DNase I activity, providing a useful platform for low-cost, label-free and convenient detection of DNase I activity. Under the optimum conditions, the proposed label-free NIR fluorescent assay gave a detection limit of 1 u mL−1, and a relative standard deviation of 3.2% for eleven replicate detections of 50 u mL−1 DNase I. The proposed assay was applied to the determination of DNase I activity in spiked human urine samples with recoveries from 99.1 to 109.0%. [ABSTRACT FROM AUTHOR]

Detecting a specific DNA sequence and discriminating single base-mismatch is critical to clinical diagnosis, paternity testing, forensic sciences, food and drug industry, pathology, genetics, environmental monitoring, and anti-bioterrorism. To this end, capillary electrophoresis (CE) coupled with the inductively coupled plasma mass spectrometry (ICP-MS) method is developed using the displacing interaction between the target ssDNA and the competitor Hg2+for the first time. The thymine-rich capture ssDNA 1is interacted with the competitor Hg2+, forming an assembled complex in a hairpin-structure between the thymine bases arrangement at both sides of the capture ssDNA 1. In the presence of a target ssDNA with stronger affinity than that of the competitor Hg2+, the energetically favorable hybridization between capture ssDNA 1and the target ssDNA destroys the hairpin-structure and releases the competitor as free Hg2+, which was then read out and accurately quantified by CE-ICP-MS assay. Under the optimal CE separation conditions, free Hg2+ions and its capture ssDNA 1adduct were baseline separated and detected on-line by ICP-MS; the increased peak intensity of free Hg2+against the concentration of perfectly complementary target ssDNA was linear over the concentration range of 30–600 nmol L−1with a limit of detection of 8 nmol L−1(3s, n= 11) in the pre-incubated mixture containing 1 μmol L−1Hg2+and 0.2 μmol L−1capture ssDNA 1. This new assay method is simple in design since any target ssDNA binding can in principle result in free Hg2+release by 6-fold Hg2+signal amplification, avoiding oligonucleotide labeling or assistance by excess signal transducer and signal reporter to read out the target. Due to element-specific detection of ICP-MS in our assay procedure, the interference from the autofluorescence of substrata was eliminated. [ABSTRACT FROM AUTHOR]

A specific resonance light scattering bioassay for homocysteine is developed on the basis of target-involved assembly of polyethyleneimine-capped Ag-nanoclusters. The bioassay permits discriminating homocysteine from cysteine, glutathione and other amino acids, and allows sensitive and selective detection of homocysteine with a detection limit of 42 nM. [ABSTRACT FROM AUTHOR]

In recent years, more and more attention has been paid to optical temperature sensing, and how to improve its accuracy is the most important issue. Herein, a new temperature sensing material, SrGd 2 Al 2 O 7 :Bi 3+ ,Mn 4+ , based on fluorescence intensity ratio was designed in this work. It has both blue-purple and red luminescence under 300 nm excitation, and the dual-emitting centers with distinct colors, the different thermal sensitivities of Bi 3+ and Mn 4+ , and the energy transfer between Bi 3+ and Mn 4+ give it excellent signal resolution and accurate temperature detection. The S a of SrGd 2 Al 2 O 7 :0.04Bi 3+ ,0.003Mn 4+ phosphor reaches a maximum value of 8.573% K -1 at 473 K, and the corresponding S r is 1.927% K -1 , both of which are significantly better than those of most other reported optical temperature sensing materials. Taking all the results into account, the SrGd 2 Al 2 O 7 :0.04Bi 3+ ,0.003Mn 4+ phosphor can be regarded as a prominent FIR-type temperature sensing material., Competing Interests: On behalf of all authors, the corresponding author states that there is no conflict of interest which could have appeared to influence the work reported in this paper., (This journal is © The Royal Society of Chemistry.)

Tiny BaSO 4 rod-based X-ray imaging is the most frequently-used method for clinical diagnosis of gastrointestinal motility disorders. The BaSO 4 rods usually have a small size to pass through the gastrointestinal tract smoothly, but suffer from unavoidably low sensitivity. Herein, we developed Bi 2 S 3 capsules as a high-performance X-ray contrast agent for gastrointestinal motility assessment for the first time. The Bi 2 S 3 capsules were synthesized by the encapsulation of commercial Bi 2 S 3 powder into commercial gelatin capsules and subsequent coating of ultraviolet-curable resin. The prepared Bi 2 S 3 capsules showed excellent biocompatibility in vitro and in vivo and superior X-ray attenuation ability due to the large atomic number and high K-edge value of Bi. The developed Bi 2 S 3 capsules can serve as a small but highly sensitive X-ray contrast agent to quantitatively assess gastrointestinal motility in a vincristine-induced gastrointestinal motility disorder model in vivo by X-ray, CT and spectral CT imaging successfully, solving the intrinsic drawbacks of clinically used BaSO 4 ., Competing Interests: The authors declare no competing financial interest., (This journal is © The Royal Society of Chemistry.)

Nitric oxide (NO) gas treatment offers a promising strategy for tumor therapy; however, its practical application is still limited due to its poor efficacy and biotoxicity which were caused by gas leakage during blood delivery. Herein, a nano-platform (CMH-OBN) composed of chlorin e6-melanin-hyaluronic acid nanoparticles (Ce6-MNP-HA, CMH) and oxidized bletilla striata polysaccharide microcapsules (Oxi-BSP) carrying NO donors was prepared for responsive and cascaded release of NO, reactive oxygen species (ROS) and its secondary metabolite reactive nitrogen species (RNS) in tumor sites. Melanin not only endowed CMH with good photothermal properties, but also helped Ce6 to produce a large number of ROS under near-infrared (NIR) irradiation. OBN microcapsules, which were sensitive to ROS, can release NO donors under the stimulation of ROS released by CMH nanoparticles under NIR irradiation and can further release NO in the tumor microenvironment (TME) with high expression of glutathione (GSH). NO could further up-regulate soluble guanylate cyclase-cyclic guanosine monophosphate (sGC-cGMP) signal pathways to relieve hypoxia, thus further enhancing the photodynamic therapy (PDT). Moreover, the cascaded release of ROS and NO could produce RNS with higher lethality, which could sequentially initiate the cellular apoptotic procedure and promote immunotherapy by activating T cells at the tumor sites. More interestingly, the CMH-OBN nano-platform could supply magnetic resonance imaging (MRI) and infrared photothermal imaging guidance for tumor therapy. In conclusion, the development of a CMH-OBN nano-platform provides a satisfactory demonstration by combining NO therapy with photothermal therapy (PTT), PDT and immunotherapy for the treatment of cancer.

Clinical diagnosis of malignant tumors using nanoprobes needs severe improvements in the aspects of sensitivity and biocompatibility. Integrating a dual-targeting strategy with the selection of human-inherent elements and molecules as raw materials shows great potential in the development of a biosafe and sensitive nanoplatform. To carry out the proposed design, we constructed a biocompatible, dual-targeting MR imaging nanoprobe, based on Fe3O4 nanoparticles (NPs) co-modified with inherently innoxious hyaluronic acid (HA) and transferrin (Tf). HA was used as both a template and a targeting molecule to form Fe3O4@HA NPs through a one-step co-precipitation method, which were then further modified with Tf to obtain the dual-targeting Fe3O4@HA@Tf NPs at room temperature. The excellent biocompatibility of the nanoprobe was demonstrated via toxicity assays in vitro and in vivo. The desirable dual-targeting ability towards tumor cells was confirmed by a cellular uptake test (Hela cells, overexpressing both CD44 and transferrin receptors), and the developed nanoprobe was successfully applied in tumor-targeted MR imaging in vivo. In summation, we developed a dual-targeting Fe3O4 nanoprobe, following a facile procedure at room temperature. The nanoprobe showed a high targeting ability towards tumor cells and excellent biocompatibility, which showed its great potential to be applied in the clinical diagnosis of tumors.

Photothermal therapy as a physical therapeutic approach has greatly attracted research interest due to its negligible systemic effects. Among the various photothermal agents, CuS nanoparticles have been widely used due to their easy preparation, low cost, high stability and strong absorption in the NIR region. However, the ambiguous biotoxicity of CuS nanoparticles limited their bio-application. So it is highly desirable to develop biocompatible CuS photothermal agents with the potential of clinical translation. Herein, we report a novel method to synthesize biocompatible CuS nanoparticles for photothermal therapy using bovine serum albumin (BSA) as a template via mimicking biomaterialization processes. Owing to the inherent biocompatibility of BSA, the toxicity assays in vitro and in vivo showed that BSA-CuS nanoparticles possessed good biocompatibility. In vitro and in vivo photothermal therapies were performed and good results were obtained. The bulk of the HeLa cells treated with BSA-CuS nanoparticles under laser irradiation (808 nm) were killed, and the tumor tissues of mice were also successfully eliminated without causing any obvious systemic damage. In summary, a novel strategy for the synthesis of CuS nanoparticles was developed using BSA as the template, and the excellent biocompatibility and efficient photothermal therapy effects of BSA-CuS nanoparticles show great potential as an ideal photothermal agent for cancer treatment.

A simple and efficient colorimetric method for the naked-eye detection and quantification of histidine in biological fluids was developed based on an indicator-displacement assay (IDA) and the Ni(2+)-histidine affinity pair. In this IDA approach, a commercially available dye, murexide, was used as the indicator and the selective detection of histidine was achieved based on the competition between indicator and histidine for the binding with Ni(2+). The competition of histidine with murexide for Ni(2+) resulted in an obvious color change of the solution from yellow to purple, and the permitted naked-eye detection of trace histidine. The developed bioassay allows the rapid, sensitive and selective detection of histidine in urine samples, and does not need complicated sample pretreatment. The detection limit was 0.4 μM with a linear range from 2 to 30 μM. The relative standard deviation for 11 replicate detections of 8 μM histidine was 2.0%. The developed sensor was successfully applied to the determination of histidine in human urine samples with recoveries from 97 to 105%.

Detecting a specific DNA sequence and discriminating single base-mismatch is critical to clinical diagnosis, paternity testing, forensic sciences, food and drug industry, pathology, genetics, environmental monitoring, and anti-bioterrorism. To this end, capillary electrophoresis (CE) coupled with the inductively coupled plasma mass spectrometry (ICP-MS) method is developed using the displacing interaction between the target ssDNA and the competitor Hg(2+) for the first time. The thymine-rich capture ssDNA 1 is interacted with the competitor Hg(2+), forming an assembled complex in a hairpin-structure between the thymine bases arrangement at both sides of the capture ssDNA 1. In the presence of a target ssDNA with stronger affinity than that of the competitor Hg(2+), the energetically favorable hybridization between capture ssDNA 1 and the target ssDNA destroys the hairpin-structure and releases the competitor as free Hg(2+), which was then read out and accurately quantified by CE-ICP-MS assay. Under the optimal CE separation conditions, free Hg(2+) ions and its capture ssDNA 1 adduct were baseline separated and detected on-line by ICP-MS; the increased peak intensity of free Hg(2+) against the concentration of perfectly complementary target ssDNA was linear over the concentration range of 30-600 nmol L(-1) with a limit of detection of 8 nmol L(-1) (3s, n = 11) in the pre-incubated mixture containing 1 μmol L(-1) Hg(2+) and 0.2 μmol L(-1) capture ssDNA 1. This new assay method is simple in design since any target ssDNA binding can in principle result in free Hg(2+) release by 6-fold Hg(2+) signal amplification, avoiding oligonucleotide labeling or assistance by excess signal transducer and signal reporter to read out the target. Due to element-specific detection of ICP-MS in our assay procedure, the interference from the autofluorescence of substrata was eliminated.