The critical impacts of pyrochar during 2,4,6-trichlorophenol photochemical remediation process: Cooperation between persistent free radicals and oxygenated functional groups.

The widespread use of polychlorophenols poses enormous environmental challenges. Biochar has the potential to accelerate the transformation of polychlorophenols. But the biochar-triggered photochemical decomposition mechanism of polychlorophenols still remains unclear. Herein, the photochemical behavior of pyrochar was comprehensively investigated in 2,4,6-trichlorophenol (TCP) remediation. Researches revealed that persistent free radicals (PFRs) and oxygenated functional groups (OFGs) on the surface of pyrochar cooperatively promoted ROS generation for TCP degradation. PFRs performed a key role of electron-donating and energy transfer in ROS conversion, especially in the activation of H2O2 into •OH. The hydroxyl groups of photosensitive components of pyrochar were photo-excited and provided electrons for enhanced ROS formation as well. With photogenerated ROS involved, more TCP was decomposed through dechlorination under light irradiation than that in the dark, in which 1O2, •OH, and •O2- were the dominant active species. During this process, stronger light intensities (3 W/m2) and shorter light wavelengths (400 nm) can provide more energy for the activation of PFRs and OFGs, promoting the decomposition of TCP. This work casts a new light on the environmental roles of pyrochar in the photochemical removal of polychlorophenol pollutants.

One-Pot Synthesis of Enzyme and Antibody/CaHPO4 Nanoflowers for Magnetic Chemiluminescence Immunoassay of Salmonella enteritidis.

In this study, through a bioinspired strategy, the horseradish peroxidase (HRP) and antibody (Ab) were co-embedded into CaHPO4 to prepare HRP-Ab-CaHPO4 (HAC) bifunctional hybrid nanoflowers by one-pot mild coprecipitation. The as-prepared HAC hybrid nanoflowers then were utilized as the signal tag in a magnetic chemiluminescence immunoassay for application in the detection of Salmonella enteritidis (S. enteritidis). The proposed method exhibited excellent detection performance in the linear range of 10-105 CFU/mL, with the limit of detection (LOD) of 10 CFU/mL. This study indicates great potential in the sensitive detection of foodborne pathogenic bacteria in milk with this new magnetic chemiluminescence biosensing platform.

One-Pot Synthesis of HRP&SA/ZIF-8 Nanocomposite and Its Application in the Detection of Insecticidal Crystalline Protein Cry1Ab.

This study reported the functionality integration of zeolitic imidazolate framework-8 (ZIF-8) with horseradish peroxidase (HRP) and streptavidin (SA) for the synthesis of a HRP&SA/ZIF-8 nanocomposite through one-pot coprecipitation. The synthesized HRP&SA/ZIF-8 nanocomposite was then employed as the ideal signal tag for application in the enzyme-linked immunosorbent assay (ELISA) and exhibited excellent sensitivity, selectivity and accuracy in the detection of insecticidal crystalline (Cry) protein Cry1Ab as a transgenic biomarker with a detection limit of 4.8 pg/mL. This proposed method provides a new way for the detection of transgenic biomarkers in food and may inspire further integration of a variety of biomolecules into ZIF-8 for applications ranging from biosensing, biomedicine, and catalysis to energy.

Biomimetic synthesis of protein-DNA-CaHPO4 hybrid nanosheets for biosensing: Detection of thrombin as an example.

Traditional strategies for coupling of proteins with DNA involve the additional modifications on protein or DNA to construct protein-DNA conjugates, resulting in complex or time-consuming coupling process. This study presented a biomimetic synthesis strategy to elaborately synthesize a new type of biomolecule-inorganic hybrid nanosheets. Horseradish peroxidase (HRP) and DNA aptamer can be easily combined with CaHPO4 via coprecipitation simultaneously to form all-inclusive HRP-aptamer-CaHPO4 hybrid (HAC) nanosheets integrating bifunction of biorecognition and signal amplification, which was proceeded in the green environment at room temperature and required no additional modifications on CaHPO4, protein and DNA. Therefore, it avoided tedious linking and purification procedures. The HAC nanosheets were then employed as the signal labels and showed excellent performance for detecting thrombin. This bioinspired approach provides great possibilities to facile and efficient immobilization of protein, DNA or even other types of biomolecules (e.g., RNA and peptide) on inorganic nanomaterials and endows great potential in the preparation of a variety of multifunctional biomolecule-CaHPO4 two-dimensional (2D) nanobiohybrids for various applications extending from biosensing to energy, biomedicine, environmental science and catalysis.

Bioinspired synthesis of protein-posnjakite organic-inorganic nanobiohybrid for biosensing applications.

This study demonstrated a facile, green and bioinspired approach to synthesize protein-posnjakite nanobiohybrid with rod-assembled hollow shuttle-like structure. Through the one-pot mild coprecipitation process, the inorganic mineral posnjakite (Cu4(SO4) (OH)6·H2O) served as a nanocarrier to efficient co-immobilization of recognition protein (streptavidin) and enzyme (horseradish peroxidase) for signal amplification, which avoids tedious linking or purification procedures and significantly simplifies the synthetic process. This nanobiohybrid was then utilized as the signal tag for immunoassays and presented excellent performance for the detection of insecticidal crystalline (Cry) protein Cry1Ab, in the linear range of 0.1-40 ng mL-1, with the limit of detection of 63 pg mL-1. This proposed strategy is expected to the integration of a variety of biomolecules with posnjakite to design diverse multifunctional nanobiohybrids for multiple applications extending from biosensors, catalysis and biomedicine to environmental science and energy.

Highly photoluminescent carbon dots derived from linseed and their applications in cellular imaging and sensing.

Carbon dots (CDs) synthesized from natural organic precursors, such as glucose, citric acid, glycerol, and chitosan, have attracted great interest since natural organic precursors provide abundant carbon sources, a variety of heteroatoms for doping (such as N, S, and P) and good biocompatibility. However, previous approaches utilized organic solvents during synthesis procedures, which limited their widespread development in biomedical applications. Herein, the facile synthesis of a new type of bright CDs through an eco-friendly method that employs linseed as a natural precursor has been reported. The as-obtained CDs possessed high quantum yield of 14.2%, excellent solubility and photostability as well as excitation-dependent photoluminescence (PL). In addition, the as-prepared CDs exhibited great potential in cell imaging owing to negligible cytotoxicity as well as excellent biocompatibility and great resistance to photobleaching. Subsequently, the as-prepared CDs were also applied in the fabrication of a biosensor for sensitive detection of butyrylcholinesterase (BChE) based on the fluorescence quenching mechanism, which could be used as an indicator for detecting pesticides and nerve gases. By monitoring the change in the fluorescence intensity of the CDs, the activity of BChE was sensitively analyzed. The limit of detection (LOD) of BChE was 0.035 mU mL-1. The as-prepared CDs have potential applications in both biosensors and bio-imaging.

Synthesis of Zn-based metal-organic frameworks in ionic liquid microemulsions at room temperature.

For the first time, Zn-metal-organic frameworks (Zn-MOFs) were prepared using Zn2+ and the aromatic ligand 1,3,5-benzenetricarboxylic acid (BTC) in ionic liquid microemulsions stabilized by the surfactant TX-100. This proposed environmentally friendly approach to synthesize Zn-MOFs is simple, requires no energy input, and operates at room temperature. The synthesized Zn-MOFs were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), single crystal X-ray diffraction and powder X-ray diffraction (XRD), thermal gravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FT-IR). The results showed that two different Zn-MOF crystals had been successfully synthesized and that [NaZn(C9H3O6)(H2O)4]·1.5H2O was prepared by using this method for the first time. The influence of different parameters such as the pH value, the ratio of reactants, and reaction time on the morphology and size of the Zn-MOFs was studied. Long rod Zn-MOFs with an average size of ∼25 µm could be obtained in the ionic liquid microemulsions with a molar ratio (organic ligand to metal ion) of 1 : 1 at pH 5.98 for 24 h. The crystal type and morphology of the Zn-MOFs could be controlled by the ionic liquid microemulsions at room temperature. This green synthesis method can be used to study their industrial production.

Mitochondrial-targeted multifunctional mesoporous Au@Pt nanoparticles for dual-mode photodynamic and photothermal therapy of cancers.

In the conventional non-invasive cancer treatments, such as photodynamic therapy (PDT) and photothermal therapy (PTT), light irradiation is precisely focused on tumors to induce apoptosis via the generation of reactive oxygen species (ROS) or localized heating. However, overconsumption of oxygen and restricted diffusion distance of ROS limit the therapeutic effects on hypoxic tumors. Herein, we developed a platform for the rapid uptake of multifunctionalized Au@Pt nanoparticles (NPs) by mitochondria in cancer cells. The mesoporous Au@Pt nanoparticles were labeled with a cell-targeting ligand (folic acid), a mitochondria-targeting group (triphenylphosphine (TPP)), and a photosensitizer (Ce6). This led to significant improvement of the PDT efficacy due to an enhanced cellular uptake, an effective mitochondrial ROS burst, and a rapid intelligent release of oxygen. Moreover, Au@Pt NPs can convert laser radiation into heat, resulting in thermally induced cell damage. This nanosystem could be used as a dual-mode phototherapeutic agent for enhanced cancer therapy and molecular targets associated with disease progression. We achieved a mitochondria-targeted multifunctional therapy strategy (a combination of PDT and PTT) to substantially improve the therapeutic efficiency.

MnO2 Nanotube-Based NanoSearchlight for Imaging of Multiple MicroRNAs in Live Cells.

Sensitive assay and imaging of multiple low-abundance microRNAs (miRNAs) in living cells remain a grand challenge. Herein, based on polyelectrolyte-induced reduction, a facile approach has been proposed to synthesize novel MnO2 nanotubes. Owing to the remarkably strong fluorescence quenching ability, low cytotoxicity, and excellent colloid stability, the as-prepared MnO2 nanotubes showed great potential for simultaneous detection and imaging of multiple miRNAs in vitro and in situ in living cells for the first time. Besides, MnO2 nanotubes can be reduced to Mn2+ by intracellular acid pH or glutathione, which may serve as an activatable contrast reagent for MRI. Therefore, the MnO2 nanotube-based probes, termed "NanoSearchlight", provide a promising, multimodal imaging tool for precise and accurate diagnosis and prognosis of cancers.

"On-Off-On" fluorescence sensor based on g-C3N4 nanosheets for selective and sequential detection of Ag+ and S2.

Detection of silver (Ag+) and sulfide (S2-) ions is important because their presence in large amounts can cause many diseases. In this study, a novel, simple, "on-off-on" fluorescence sensor based on g-C3N4 nanosheets for sequential detection of Ag+ and S2- was designed. The fluorescence signal of the g-C3N4 nanosheets is quenched because Ag+ chelates with the N of the g-C3N4 nanosheets, leading to photoinduced electron transfer from the sheets to Ag+. After adding S2-, the fluorescence of the g-C3N4 nanosheets is recovered due to formation of Ag2S, which activates the fluorescence of the g-C3N4 nanosheets. The recovery efficiency was found to increase with increasing concentrations of S2-, with linear calibration ranging from 0nmol/L to 30nmol/L. Other potentially interfering species, such as SO42-, PO43-, HPO42-, H2PO4-, CO32-, NO3-, Ac-, and HCO3-, presented negligible effects on S2- detection. Moreover, the proposed sensor exhibited several advantages, including low cost, easy preparation, rapid detection, excellent biocompatibility, and a switchable fluorescence response. These attributes make this fluorescent sensor a promising tool for environmental applications.

One-pot bioinspired synthesis of all-inclusive protein-protein nanoflowers for point-of-care bioassay: detection of E. coli O157:H7 from milk.

Protein-protein conjugates play a vital role in bioassays with their inherent functions of biological recognition and signal amplification. Herein, a one-pot green method for synthesis of all-inclusive protein-protein nanoflowers has been developed. The protein-protein nanoflowers integrate both essential functions of biological recognition and signal amplification, and they were used as ideal signal labels for the sensitive point-of-care detection of Escherichia coli O157:H7. Especially noteworthy, the prepared Con A-invertase-CaHPO4 hybrid nanoflowers simultaneously loaded sufficient invertase and enhanced the activity of the immobilized invertase, which fits well with the requirements of signal labels for bioassays. Due to the conversion of sucrose to glucose by invertase, Con A-invertase-CaHPO4 hybrid nanoflowers were successfully used for the reliable point-of-care detection of food pathogens by a personal glucose meter. The presented approach successfully resolved the bottleneck in preparing protein-protein conjugate-based signal labels for bioassays using enzyme-based signal amplification strategies, which holds great promise to develop on-demand protein-protein conjugates for a variety of applications extending from biosensors and biomedicine to energy, environmental monitoring and remediation.

Bioinspired Synthesis of All-in-One Organic-Inorganic Hybrid Nanoflowers Combined with a Handheld pH Meter for On-Site Detection of Food Pathogen.

With a mild elaborately bioinspired one-pot process, Con A-GOx-CaHPO4 nanoflowers are prepared. Employing the as-prepared all-in-one hybrid nanoflowers as signal tags, a simple but potentially powerful amplification biosensing technology for the detection of food pathogen with excellent simplicity, portability, sensitivity, and adaptability is achieved.