PBS Solution Research Articles

Nanoporous Nickel-Molybdenum Oxide with an Oxygen Vacancy for Electrocatalytic Nitrogen Fixation under Ambient Conditions.

The electrochemical nitrogen reduction reaction (NRR) is regarded as a sustainable method for N2 fixation. N2 adsorption and N≡N cleavage are the main challenges for the NRR. Herein, we propose a potential approach to enhance N2 activation via introducing oxygen vacancies (OVs) into nanoporous NiO/MoO3. Nanoporous NiO/MoO3 with OVs (np-OVs-NiO/MoO3) is prepared by a two-step process of dealloying and solid-state reaction. np-OVs-NiO/MoO3 exhibits a high NH3 yield of 35.4 μg h-1 mgcat-1 and a Faradaic efficiency (FE) of 10.3% in 0.1 M PBS solution. The introduction of OVs enhances the conductivity, N2 adsorption, and catalytic performance of np-NiO/MoO3. The dual-metal sites with OVs have a unique electronic structure in favor of the "π back-donation" behavior, which decreases the energy barrier of protonation steps and improves the whole NRR process. This approach provides new insight into the design of composite transition metal oxides with OVs for the NRR catalyst under ambient conditions.

3D Printing of Thermoresponsive Hydrogel Laden with an Antimicrobial Agent towards Wound Healing Applications.

Thermoresponsive hydrogel-based wound dressings with an incorporated antimicrobial agent can be fabricated employing 3D printing technology. A novel printable ink containing poly(N-isopropylacrylamide) (PNIPAAm) precursors, sodium alginate (ALG), methylcellulose (MC) that is laden with a mixture of octenidine dihydrochloride and 2-phenoxyethanol (Octenisept®, OCT) possess accurate printability and shape fidelity. This study also provides the protocol of ink’s use for the 3D printing of hydrogel scaffolds. The hydrogel’s physicochemical properties and drug release profiles from the hydrogel specimens to the external solution have been determined at two temperatures (20 and 37 °C). The release test showed a sustained OCT delivery into ultrapure water and the PBS solution. The temperature-responsive hydrogel exhibited antimicrobial activity against Staphylococcus aureus, Candida albicans, and Pseudomonas aeruginosa and demonstrated non-cytotoxicity towards fibroblasts. The thermoresponsive behavior along with biocompatibility, antimicrobial activity, and controlled drug release make this hydrogel a promising class of materials for wound dressing applications.

Mesoporous Silica Nanoparticles as a System for Ciprofloxacin Drug Delivery; Kinetic of Adsorption and Releasing

Mesoporous silica (MPS) nanoparticle was prepared as carriers for drug delivery systems by sol–gel method from sodium silicate as inexpensive precursor of silica and Cocamidopropyl betaine (CABP) as template. The silica particles were characterized by SEM, TEM, AFM, XRD, and N2adsorption–desorption isotherms. The results show that the MPS particle in the nanorange (40-80 nm ) with average diameter equal to 62.15 nm has rods particle morphology, specific surface area is 1096.122 m2/g, pore volume 0.900 cm3/g, with average pore diameter 2.902 nm, which can serve as efficient carriers for drugs. The adsorption kinetic of Ciprofloxacin (CIP) drug was studied and the data were analyzed and found to match well with pseudo-first order kinetic model. The CIP drug-loaded mesoporous silica (CIP-mSiO2) nanoparticles has capacity of about 16.3 mg drug/ mg mSiO2 were achieved, and capable of releasing 26% and 98.6% of their drug content after 90 min in water and PBS solution(pH,7.4) respectively. In-vitro controlled release studies of CIP in Simulated Body Fluid were carried out under stirring conditions. A study on release kinetics and mechanism using Koresmeyer-Pepps model, first order kinetic, and kopcha model shows that the Korsmeyer-Peppas and Kopcha models, both conform more closely to the release data.

Flexible and Printed Capacitive Sensor with Graphene Oxide As Active Layer for Prothrombin Time Measurement

Prothrombin time test is commonly used to monitor and regulate the coagulation cascade process in various clinical conditions, such as cardiac surgery or recurrent thrombosis [1]. After the extrinsic pathway is triggered by the thromboplastin reagent (tissue), several biochemical interactions between the blood factors occur [2]. Graphene materials are widely used for biosensor applications since they present high sensitivity and excellent mechanical and electrical properties [3]. To monitor these cascade effects based on the change of the electrical properties, we developed a printed and flexible electrochemical sensor using conductive ink as electrodes and graphene oxide as an active layer. The silver nanoparticle electrodes were printed on a glossy paper substrate by an inkjet printer and sintered at 75 °C for 30 min. A vinyl chamber was plotted and attached over the substrate. Graphene oxide (GO) was drop-casted (1-, 2-, 3-layers) over the active area in several devices and then dried at 75 °C for 15 min. For the electrical characterization, phosphate-buffered saline (PBS; pH 7.4) solution was injected in the chamber and the capacitance of the device was measured by a parameter analyzer while applying a DC bias of 10 mV in a frequency of 1 kHz. Next, the paper chip was cleaned, and the thromboplastin reagent (10 µL) was inserted. Then, during the capacitance measurement, the human plasma was mixed to the reagent inside the chamber. The devices without the active layer presented higher capacitance values (Figure 1) than the ones with graphene oxide while using PBS solution as an analyte. For the prothrombin test, a change in the capacitance values (Figure 2(a)) was monitored for each fabricated device. However, there were different behaviors in the capacitance curves, indicating that the thickness of the graphene oxide affects the sensitivity of the system while monitoring the clotting formation. Also, the fibrin clot formation increases viscosity, consequently increasing the electrical impedance over the active layer. Considering the capacitance curves for 5 min (Figure 1b-d)), the devices with 2- and 3-layers of graphene oxide demonstrated a better response to the biochemical reaction that was happening in the plasma after the addition of the reagent. The future studies are related to improving the fabrication process of the active layer enhancing reproducibility and sensitivity. Then, a fully-printed sensor will be developed for coagulation test using a small volume of whole blood samples. And a mathematical implementation will be used to determine the exact prothrombin time based on the slope of the response curve.

Silicone-Rubber Based Multiplex Ion-Sensitive Light-Addressable Potentiometric Sensor (ISLAPS) System for Physiological Ions Detection

Silicone-Rubber Based Multiplex Ion-Sensitive Light-Addressable Potentiometric Sensor (ISLAPS) System for Physiological Ions Detection

Industry Viable Electrochemical DNA Detection Sensor Architecture Via a Stem-Loop Methylene Blue Redox Reporter and Rapid in Situ Probe Mobilization Method

Pharmacogenomics is one of the endeavours in the modern acute health care sector due to the complexity of the drug reactions associated with the patients' genetic markers[1]. Therefore, the availability of patient pharmacogenetic marker testing at the point-of-care (POC) setting will help the clinicians to prescribe and personalize the medication to ensure maximum efficiency with minimal adverse drug reactions (ADR). In this regard, we focused on developing a HLA-B*15:02 pharmacogenetic biomarker testing known to cause specific ADRs for Carbamazepine[2].In this study, disposable screen-printed electrodes (SPE) as the planar sensor surfaces and a sequence-specific stem-loop probe modified with a methylene blue redox (MB) reporter was used to detect the targeted DNA sequence of HLA-B*15:02. The oligo probe with MB reporter at the 3′ end was designed to incorporate 25 nucleotides to detect the specific region. The disulphide-reducing reagent, Tris(2-carboxyethyl) phosphine hydrochloride was introduced to reduce the S-S bond of the oligo probe. The probe immobilization on the working electrode area was performed using the fully automated non-contact dispensing system sciFLEXARRAYER SX by dispensing an array of droplets of 50 µM probe mixture into accurate positioning of the gold working electrode area of SPEs (220AT DropSens). Around 20 SPEs were loaded, and probes were printed during a single batch processing task. Two printing runs were performed, and a total of N=30 biosensors were used in the experimental procedure. The electrochemical behaviour of the sensor was studied by performing the square wave voltammetry (SWV) measurements from -0.4 V to -0.1 V, with a modulation amplitude of 0.02 V and frequency of 25 Hz at a scan rate of 0.026 V/s (Autolab-PGSTAT204). The target hybridization time was fixed at 30 minutes. The p-values ≤ 0.05 was considered statistically significant.The SWV measurements on the sensors with 75 µl, 1X PBS solution (Baseline) showed a well-defined peak at -0.31 V with the standard deviation (SD) of 0.004 V (Ntotal=30) which is consistent with the potential of the MB redox moiety. The statistical t-test has been shown that no statistical significance (p=0.1760) between the two printing runs with the peak heights of 640.5 nA ± 151.2 nA (SD). Upon target hybridization, measured peak heights showed that (a) 152.0 nA ± 23.3 nA for the 50 µM Positive control (oligo with the sequence complementary to the probe), (b) 231.8 nA ± 54.8 nA for the 50 µM Negative control (oligo with the non-complementary sequence to the probe), and (c) 226.2 nA ± 93.2 nA for the Blank-oligo free sensors. This shows ~34% signal suppression in Positive control hybridized sensors, whereas insignificance difference between the Negative and Blank samples hybridized sensors. Furthermore, statistical analysis (one-way ANOVA) show that a statistical significance (p=0.0250) for the Positive vs. Negative, a statistical significance (p=0.0388) for the Positive vs. Blank sample, and no statistical significance (p=0.9793) for the Negative vs. Blank sample. These results confirmed that a complementary target binding event in the stem-loop probe results in a significant signal decrease and the possibility of using this 'signal-off biosensor architecture in detecting HLA-B*15:02 pharmacogenetic biomarker testing platform.It was found that only 6 µl probe mixture was required to cover one sensor. Accordingly, the calculated probe surface density was equivalent to ~1.43×1015 molecules/cm2, which will be 3 order of magnitudes higher than the typical probe surface density (~1012) of biosensors[3]. This high level of probe surface density on the sensors was achieved by printing a high concentration of low volume of redox probes. This will not be possible in the typical wet bench probe immobilization methods. Also, it showed a significantly higher level of faradaic current generated in the biosensor and clear differentiation of the targets. Therefore, this work showcases encouraging results of biosensor architecture, rapid probe immobilization method, the possibility of using the ultra-low volume of probe reagents, and high-throughput productions. This suggested that further development of this pharmacogenetic biomarker testing platform will enhance the technical feasibility and enable the transition of this biosensor from the research to industry. Acknowledgements This work used the Melbourne Centre for Nanofabrication (MCN) in the Victorian Node of the NCRIS-enabled Australian National Fabrication Facility (ANFF). References FDA. Table of Pharmacogenomic Biomarkers in Drug Labeling. Available from: https://www.fda.gov/drugs/science-and-research-drugs/table-pharmacogenomic-biomarkers-drug-labeling.Soraya, G.V., et al., An interdigitated electrode biosensor platform for rapid HLA-B*15:02 genotyping for prevention of drug hypersensitivity. Biosens Bioelectron, 2018. 111: p. 174-183.Ricci, F., et al., Effect of molecular crowding on the response of an electrochemical DNA sensor. Langmuir, 2007. 23(12): p. 6827-6834.

Industry Viable Electrochemical DNA Detection Sensor Architecture Via a Stem-Loop Methylene Blue Redox Reporter and Rapid in Situ Probe Mobilization Method

Pharmacogenomics is one of the endeavours in the modern acute health care sector due to the complexity of the drug reactions associated with the patients' genetic markers[1]. Therefore, the availability of patient pharmacogenetic marker testing at the point-of-care (POC) setting will help the clinicians to prescribe and personalize the medication to ensure maximum efficiency with minimal adverse drug reactions (ADR). In this regard, we focused on developing a HLA-B*15:02 pharmacogenetic biomarker testing known to cause specific ADRs for Carbamazepine[2].In this study, disposable screen-printed electrodes (SPE) as the planar sensor surfaces and a sequence-specific stem-loop probe modified with a methylene blue redox (MB) reporter was used to detect the targeted DNA sequence of HLA-B*15:02. The oligo probe with MB reporter at the 3′ end was designed to incorporate 25 nucleotides to detect the specific region. The disulphide-reducing reagent, Tris(2-carboxyethyl) phosphine hydrochloride was introduced to reduce the S-S bond of the oligo probe. The probe immobilization on the working electrode area was performed using the fully automated non-contact dispensing system sciFLEXARRAYER SX by dispensing an array of droplets of 50 µM probe mixture into accurate positioning of the gold working electrode area of SPEs (220AT DropSens). Around 20 SPEs were loaded, and probes were printed during a single batch processing task. Two printing runs were performed, and a total of N=30 biosensors were used in the experimental procedure. The electrochemical behaviour of the sensor was studied by performing the square wave voltammetry (SWV) measurements from -0.4 V to -0.1 V, with a modulation amplitude of 0.02 V and frequency of 25 Hz at a scan rate of 0.026 V/s (Autolab-PGSTAT204). The target hybridization time was fixed at 30 minutes. The p-values ≤ 0.05 was considered statistically significant.The SWV measurements on the sensors with 75 µl, 1X PBS solution (Baseline) showed a well-defined peak at -0.31 V with the standard deviation (SD) of 0.004 V (Ntotal=30) which is consistent with the potential of the MB redox moiety. The statistical t-test has been shown that no statistical significance (p=0.1760) between the two printing runs with the peak heights of 640.5 nA ± 151.2 nA (SD). Upon target hybridization, measured peak heights showed that (a) 152.0 nA ± 23.3 nA for the 50 µM Positive control (oligo with the sequence complementary to the probe), (b) 231.8 nA ± 54.8 nA for the 50 µM Negative control (oligo with the non-complementary sequence to the probe), and (c) 226.2 nA ± 93.2 nA for the Blank-oligo free sensors. This shows ~34% signal suppression in Positive control hybridized sensors, whereas insignificance difference between the Negative and Blank samples hybridized sensors. Furthermore, statistical analysis (one-way ANOVA) show that a statistical significance (p=0.0250) for the Positive vs. Negative, a statistical significance (p=0.0388) for the Positive vs. Blank sample, and no statistical significance (p=0.9793) for the Negative vs. Blank sample. These results confirmed that a complementary target binding event in the stem-loop probe results in a significant signal decrease and the possibility of using this 'signal-off biosensor architecture in detecting HLA-B*15:02 pharmacogenetic biomarker testing platform.It was found that only 6 µl probe mixture was required to cover one sensor. Accordingly, the calculated probe surface density was equivalent to ~1.43×1015 molecules/cm2, which will be 3 order of magnitudes higher than the typical probe surface density (~1012) of biosensors[3]. This high level of probe surface density on the sensors was achieved by printing a high concentration of low volume of redox probes. This will not be possible in the typical wet bench probe immobilization methods. Also, it showed a significantly higher level of faradaic current generated in the biosensor and clear differentiation of the targets. Therefore, this work showcases encouraging results of biosensor architecture, rapid probe immobilization method, the possibility of using the ultra-low volume of probe reagents, and high-throughput productions. This suggested that further development of this pharmacogenetic biomarker testing platform will enhance the technical feasibility and enable the transition of this biosensor from the research to industry. Acknowledgements This work used the Melbourne Centre for Nanofabrication (MCN) in the Victorian Node of the NCRIS-enabled Australian National Fabrication Facility (ANFF). References FDA. Table of Pharmacogenomic Biomarkers in Drug Labeling. Available from: https://www.fda.gov/drugs/science-and-research-drugs/table-pharmacogenomic-biomarkers-drug-labeling.Soraya, G.V., et al., An interdigitated electrode biosensor platform for rapid HLA-B*15:02 genotyping for prevention of drug hypersensitivity. Biosens Bioelectron, 2018. 111: p. 174-183.Ricci, F., et al., Effect of molecular crowding on the response of an electrochemical DNA sensor. Langmuir, 2007. 23(12): p. 6827-6834.

Interdigitated Electrode Arrays for Electrochemical Immunosensing of Interleukin-6 in Cerebrospinal Fluid (CSF) and Serum

Electrochemical immunosensors combine the advantages of electrochemical transducers such as low cost, potential for miniaturization, and quantified readout with the selective properties of immunochemical recognition elements. Here we describe a simple, label-free electrochemical immunosensor for the rapid detection of traumatic brain injury (TBI) by quanitifcation of a cytokine interleukin-6 (IL-6) in cerebrospinal fluid (CSF). The sensor system consists of gold interdigitated electrode arrays (IDEAs) that are modified with self-assembled monolayers (SAMs) and IL-6 antibodies (IL-6 mAb) for antigen recognition and capture. Electrode modification was confirmed using surface characterization (FT-IR, fluorescence) and electrochemically via EIS. The sensor performance was evaluated in IL-6 spiked PBS solution: the LOD was determined to be 1.63 pg/mL, with a linear range across 4 orders of magnitude. The sensor exhibits selectivity against non-target cytokines TNF-α and IL-10. The detection of CSF and serum IL-6 using the outlined system will be discussed for use as a point-of-care (POC) diagnostic and prognostic tool for TBI.

Designing novel anticancer drug release vehicles based on mesoporous functionalized MCM-41 nanoparticles

Nanoparticles of mesoporous MCM-41 silica were synthesized, functionalized by 8-20% of hexamethylenetetramine (HMT) and employed as effective drug carriers. The carriers’ mesopores were filled with the cyclophosphamide (CP) anticancer medicine. The pore size, pore volume and surface area of pure MCM-41 were obtained equal to 32.54 Å, 0.89 cm3/g and 996.84 m2/g but they were noticeably decreased for the HMT-functionalized MCM-41 materials approving the HMT molecules were bound onto the surfaces and pores of such samples. The release of drug was performed in three neutral PBS, alkaline and acidic solutions. A sharply enhanced CP release was observed in approximately 24 h (burst release) while subsequently release of the drug was gradually boosted within 7 days indicating a sustained release behavior. The maximum drug release amount was measured in alkaline medium, moderate quantity in neutral solution and minimum value in acidic environment. The kinetic of the drug release was examined using the Korsmeyer-Peppas, Hixson-Crowel, Higuchi, first-order, and zero-order models and it was revealed that the CP release from the nanocarriers obeyed the Korsmeyer-Peppas model. Finally, it was decided that the MCM-41 sample containing 14% HMT was the most appropriate system as it had high/favorable quantities of drug loading plus drug release.

Hemostatic wound dressings based on drug loaded electrospun PLLA nanofibrous mats

Novel wound dressings were prepared using electrospun nanofibrous PLLA mats loaded with aluminum chloride (AlCl3), gentamicin sulphate (GS) and/or lidocaine hydrochloride (LHc) as a hemostatic, antibiotic, and local anesthetic drug, respectively. Structural characterization of the prepared mats was performed using FTIR spectroscopy, whereas morphological characteristics were determined using SEM micrographs of the fibers. For mats loaded with AlCl3, the majority of the fibers diameters were in the range [400–500 nm]. The wettability of the mats was investigated using contact angles method. Hemostasis tests have shown that all the prepared mats have better hemostatic efficiency than gauze bandage. However, mats loaded with only AlCl3 30%w/w have the best hemostatic performance with a decrease in blood clotting time of 80% and an increase in blood absorption capacity of 178% in comparison with gauze bandage. GS release kinetics in PBS solution was investigated. The experimental results showed that the release kinetics follows Korsmeyer-Peppas model with a correlation factor R2 = 0.999 and n = 0.1.

Effect of Cu on the passivity of Ti–xCu (x = 0, 3 and 5 wt%) alloy in phosphate-buffered saline solution within the framework of PDM-II

The effect of copper content on the passivity of Ti–xCu alloys in a phosphate-buffered saline electrolyte (pH 7.4), in the steady-state condition, was examined using potentiostatic polarization, electrochemical impedance spectroscopy, and Mott-Schottky analysis. The study demonstrates that the oxide layer forms on the Ti–xCu alloys surface have n-type semiconducting character, and the steady-state thickness of the oxide layer is observed linearly and depends on the applied potential. The study observations are in line with the predictions of the Point Defect Model (PDM-II), which provides a physiochemically realistic description of the oxide layer formation on Ti–xCu alloys. The observations reveal that the Cu additions result in a decrease in the charge transfer resistance and capacitances associated with the hydroxide and barrier layer, an increase in the donor density, and reduce the electrochemical resistance of the Ti–xCu alloys. The study also exhibits that the decrease in the steady-state current density after the initial addition of 3 wt% of Cu is attributed to the progressive substitution of copper on the cation sublattice of the film resulting in enhanced electrostatic interaction between the immobilized copperCuTix′, and the mobile cation interstitialsCui+, which carries the excess current over and that conveyed by oxygen vacancies Vo•• in the barrier layer. Moreover, it is also observed that over a hundred-year implant period, about 0.006 cm (0.06 mm) of Ti–3Cu alloy is predicted to lose due to steady-state corrosion in the PBS solution under the given set of conditions, it is further seen that, as the Cu amount increased from 3 wt% to 5 wt% in the Ti–xCu alloys, the steady-state corrosion rate decreases.

Development of an Acid-Labile Ketal Linked Amphiphilic Block Copolymer Nanoparticles for pH-Triggered Release of Paclitaxel.

Here, we report on the construction of biodegradable poly(ethylene oxide monomethyl ether) (MPEO)-b-poly(ε-caprolactone) (PCL) nanoparticles (NPs) having acid-labile (acyclic ketal group) linkage at the block junction. In the presence of acidic pH, the nanoassemblies were destabilized as a consequence of cleaving this linkage. The amphiphilic MPEO-b-PCL diblock copolymer self-assembled in PBS solution into regular spherical NPs. The structure of self-assemble and disassemble NPs were characterized in detail by dynamic (DLS), static (SLS) light scattering, small-angle X-ray scattering (SAXS), and transmission electron microscopy (TEM). The key of the obtained NPs is using them in a paclitaxel (PTX) delivery system and study their in vitro cytostatic activity in a cancer cell model. The acid-labile ketal linker enabled the disassembly of the NPs in a buffer simulating an acidic environment in endosomal (pH ~5.0 to ~6.0) and lysosomal (pH ~4.0 to ~5.0) cell compartments resulting in the release of paclitaxel (PTX) and formation of neutral degradation products. The in vitro cytotoxicity studies showed that the activity of the drug-loaded NPs was increased compared to the free PTX. The ability of the NPs to release the drug at the endosomal pH with concomitant high cytotoxicity makes them suitable candidates as a drug delivery system for cancer therapy.

Amino acid-functionalized carbon quantum dots for selective detection of Al3+ ions and fluorescence imaging in living cells.

Carbon quantum dots (CQDs) are drawing tremendous attention due to their unique photoluminescence property and fascinating functions. Herein, we prepared novel CQDs functionalized with amino acids (AA-CQDs) by a one-pot hydrothermal method for selective detection of Al3+ ions and fluorescence imaging. The prepared AA-CQDs exhibit a novel triple-excitation and single-colour emission for fluorescent property. In addition, the AA-CQDs have a high absolute quantum yield (24.23%) and quantum lifetime (13.29ns). Moreover, the AA-CQDs exhibit high selectivity and sensitivity for Al3+ by fluorescence enhancement. In pH7.4 PBS solution, there was a good linear relation between the fluorescence intensity and the concentration of Al3+ in the range of 1-20μmolL-1; the limit of detection (3σ) was only 0.32μmolL-1. Furthermore, an AA-CQD probe was also utilized for detection of Al3+ in living cells based on excellent biocompatibility and endocytosis. Based on the concentration of Al3+ ions in cells and apoptosis data, there will be a quick reflect of apoptosis induced by aluminium ions via the fluorescence intensity of the AA-CQD probe. This work will set the stage for developing novel CQD-based biosensors in cell research.

Preclinical evaluation of a novel anti-mesothelin immunotoxin based on a single domain antibody as the targeting ligand

Pancreatic cancer, as one of the most aggressive and lethal malignancies in the world, is lack of effective treatment. Constructing immunotoxin molecules to target the mesothelin (MSLN) receptor is a potential therapeutic strategy for pancreatic cancer and other related malignant tumors, with some molecules being tested in clinical trials. However, currently, there are still some limitations in its applications, such as the difficulty of the preparation of drug molecules, the limited effectiveness of drugs, and the inadequacy of drug safety and immunogenicity. In this study, we constructed a novel type of anti-MSLN immunotoxin, A1-PE24X7, in which a single domain antibody (sdAb) molecule was used as the target ligand and an improved PE24X7 toxin with reduced off-target toxicity and immunogenicity was used as the effector. Unlike conventional immunotoxins, the designed A1-PE24X7 could be easily expressed in the E. coli system in the form of a soluble protein with a good yield (15-–20 mg/L), avoiding the complex process of denaturation and refolding of inclusion bodies, and it can be conveniently stored in PBS solution for more than 7 days at 4 °C, showing high storage stability. Cell-based experiments showed that A1-PE24X7 entered MSLN-expressing tumor cells in a receptor-mediated manner and killed these cells with an EC50 in the low nanomolar range (0.13 nM against NCI-N87 cells and 0.79 nM against AsPC-1 cells) and it showed ideal selectivity for the MSLN receptor (>100 nM against receptor negative PC3 cells). In animal-based experiments, A1-PE24X7 had tumor enrichment ability in relation to MSLN-positive tumors and showed strong tumor killing and inhibition in mouse models of pancreatic cancer and gastric cancer. Five injections of 3.0 mg/kg A1-PE24X7 significantly reduced the tumor volume of gastric NCI-N87 cancer and also significantly inhibited the growth of pancreatic AsPC-1 cancer. In addition, the maximum tolerable dosage (MSD) of A1-PE24X7 to mice was higher than 15 mg/kg, showing that A1-PE24X7 has a relatively broad therapeutic window. These preclinical results indicate that this strategy has good potential for application to the treatment of pancreatic cancer and other tumors with high MSLN expression.

DNA tetrahedron-mediated immune-sandwich assay for rapid and sensitive detection of PSA through a microfluidic electrochemical detection system

Prostate-specific antigen (PSA) is the most widely used biomarker for the early diagnosis of prostate cancer. Existing methods for PSA detection are burdened with some limitations and require improvement. Herein, we developed a novel microfluidic–electrochemical (μFEC) detection system for PSA detection. First, we constructed an electrochemical biosensor based on screen-printed electrodes (SPEs) with modification of gold nanoflowers (Au NFs) and DNA tetrahedron structural probes (TSPs), which showed great detection performance. Second, we fabricated microfluidic chips by DNA TSP-Au NF-modified SPEs and a PDMS layer with designed dense meandering microchannels. Finally, the μFEC detection system was achieved based on microfluidic chips integrated with the liquid automatic conveying unit and electrochemical detection platform. The μFEC system we developed acquired great detection performance for PSA detection in PBS solution. For PSA assays in spiked serum samples of the μFEC system, we obtained a linear dynamic range of 1–100 ng/mL with a limit of detection of 0.2 ng/mL and a total reaction time <25 min. Real serum samples of prostate cancer patients presented a strong correlation between the “gold-standard” chemiluminescence assays and the μFEC system. In terms of operation procedure, cost, and reaction time, our method was superior to the current methods for PSA detection and shows great potential for practical clinical application in the future.

Self-assembly, pH-responsibility and controlled release of doxorubicin of PDEAEMA-PEG-PDEAEMA triblock copolymers: effects of PEG length

Effects of poly(ethylene glycol) (PEG) block length on the self-assembly of a series of pH-sensitive poly(N,N-diethylaminoethyl methacrylate)m-PEGn-poly(N,N-diethylaminoethyl methacrylate)m triblock copolymers (PDEAEMAm-PEGn-PDEAEMAm) have been studied. The synthesized triblock copolymers have an almost fixed PDEAEMA block length (m ≈ 65) and varying PEG block lengths (n = 11, 20, 89 or 134). The acid–base titration results show that the pKa value of the block copolymer shifts from 6.84 to 7.08 when the PEG block length increases from 11 to 134, indicating that the pH-sensitivity of the triblock copolymer can be adjusted through changing the PEG block length. With the increase of the hydrophilic PEG block length, the critical micelle concentration value of the triblock copolymer obtained from fluorescence spectroscopy changes from 5.50 × 10–3 to 13.23 × 10–3 mg mL−1. The block copolymers can self-assemble into the micelles in PBS solution at pH 7.4, and the average size of the self-assembly decreases from 178 nm to 45 nm with the increase of the PEG block length as determined by dynamic light scattering. The block copolymers show great biocompatibility in the cytotoxicity assay. Results from these triblock copolymers in the drug-controlled release indicate that the release rate of doxorubicin-loaded micelles at pH 5.0 is faster than that at pH 7.4, and the cumulative drug release in 48 h at pH 5.0 increases from 70.4% to 89.8% with the decrease of the PEG block length. Accordingly, this PDEAEMA65-PEGn-PDEAEMA65 copolymer is an excellent carrier for controllable drug delivery and release.

An electrochemical biosensor for direct detection of hepatitis C virus

This paper is aimed at the development of a biosensor for direct detection of Hepatitis C virus (HCV) surface antigen: envelope protein (E2). A recombinant LEL fragment of biological cell receptor CD81 and two short synthetic peptides imitating the fragment of LEL sequence of CD81 (linear and loop-like peptides) capable of specific binding to E2 were tested as molecular recognition elements of the biosensor. For this purpose the selected ligands were immobilized to the surface of a screen-printed electrode utilized as an electrochemical sensor platform. The immobilization parameters such as the ligand concentration and the immobilization time were carefully optimized for each ligand. Differential pulse voltammetry used to evaluate quantitatively binding of E2 to the ligands revealed their similar binding affinity towards E2. Thus, the linear peptide was selected as a less expensive and easily prepared ligand for the HCV biosensor preparation. The resulting HCV biosensor demonstrated selectivity towards E2 in the presence of interfering protein, conalbumin. Moreover, it was found that the prepared biosensor effectively detected E2 bound to hepatitis C virus-mimetic particles (HC VMPs) at LOD value of 2.1∙10−5 mg/mL both in 0.01 M PBS solution (pH 7.4) and in simulated blood plasma.

Rapid and facile laser-assistant preparation of Ru-ZIF-67-derived CoRu nanoalloy@N-doped graphene for electrocatalytic hydrogen evolution reaction at all pH values

High temperature pyrolysis needs complicated and harsh preparative condition, such as inert gas protection, long reaction time and high pyrolysis temperature. This work reported that a cobalt-ruthenium nanoalloy coated with nitrogen- doped graphene (CoRu@NG-x) was rapidly prepared from Ru-ZIF-67 as precursors by laser engraving in air environment and at room temperature for the first time. The addition of a small amount of ruthenium in cobalt can further improve the hydrogen catalytic performance. CoRu@NG-3 (Ru, 0.18wt%) is an efficient HER electrocatalyst in a wide pH range. Compared with the reported ruthenium alloys, the content of ruthenium in CoRu@NG-3 is the lowest. It's worth noting that the optimal CoRu@NG-3 shows overpotentials of 62, 52 and 88 mV at the current density of 10 mA cm−2 in 1.0 M KOH, 0.5 M H2SO4 and 1.0 M PBS solution for HER catalysis. CoRu@NG-3 also has a good stability under all pH conditions. This study may offer a novel strategy to rapidly prepare electrode materials at room temperature and in the air.

O-nitrobenzyl liposomes with dual-responsive release capabilities for drug delivery

To improve the therapeutic efficacy of anticancer drugs and reduce its toxic side effects, we synthesized a series of amphiphilic o-nitrobenzyl molecules 4-(4-N,N,N,N-dicarboxymethyl-diethylenetriamino)acetoxymethyl-3-nitro-N,N-dialk-ylbenzamide (N,N-NB-DTPA) with good photolysis property and acid sensitivity. Simultaneously, N, N-NB-DTPA liposomes composed of the o-nitrobenzyl molecules have good biocompatibility, low hemolysis rate and cytotoxicity, and the drug encapsulation efficiency of the liposomes exceeds 70%. N, N-NB-DTPA-DOX liposomes possess good stability and can keep uniform distribution in PBS solution for 10 days. The drug release rate of these drug-loaded liposomes reaches to the maximums under pH 5.0 and 30 min UV irradiation, revealing pH/UV dual-responsiveness of these drug-loaded liposomes. The low pH makes DOX separate from these drug-loaded liposomes, and the UV irradiation leads to o-nitrobenzyl ester bond cleave, which contribute to accelerate the release of drug from drug-loaded liposomes. Furthermore, N, N-NB-DTPA-DOX liposomes after UV irradiation have better therapeutic effect than single DOX·HCl, which may result from the production of nitrosobenzaldehyde derivatives after UV irradiation.

&lt;p&gt;&lt;strong&gt;Effect of &lt;em&gt;Panax notoginsenoside&lt;/em&gt; Rg1 on bidirectional regulation of blood glucose level in mice&lt;/strong&gt;&lt;/p&gt;

Panax notoginseng saponin (PNS) is one of the key bioactive components of dry root and rhizome of Panax notoginseng (Burk.), a well known as Tianqi in Traditional Chinese Medicine (TCM). Although PNS has been shown to possess various pharmacological activities, such as being antithrombotic, neuroprotective, anti-inflammatory and hypolipidemic, etc., its effects on blood glucose levels have not been well documented but for some preliminary reports. It deserves a detailed in vivo investigation in animal model. Thus, to investigate the bi-directional regulation of ginsenoside Rgl (Rg1) on blood glucose in mice, Rg1 with high purity was prepared from panax notoginseng saponins by normal phase silica gel column chromatography and reverse phase C18 preparative chromatography. Normal 4-week-old mice were randomly divided into normal control group, normal control group with Rg1, glucose gavage control group, glucose gavage control group with Rg1, insulin treated control group and overnight fasting control group with or without Rg1 (n = 10). The mice in the control group were intragastrically administered with PBS solution, and the mice in the Rg1 groups were intragastrically administered with Rg1 once a day at the doses of 0.5, 1.0 and 1.5 mg/kg for consecutive 7 days. After the last drug, blood glucose (BG) levels were measured at 0.5 (30 min) and 1 h after administration using a simultaneous automatic biochemical analyzer to observe the effect of Rg1 on BG levels. Compared with the model group, Rg1 significantly decreased the BG levels of hyperglycemic mice induced by glucose gavage (P <0.05), significantly increased the BG level of overnight fasted mice (P <0.05), and had no significant effects on the normal group of mice. Panax notoginseng saponin Rgl has a significant bidirectional regulatory effect on glucose levels in mice. When the blood glucose of mice increases, intragastric administration of Rg1 can effectively reduce the blood glucose; conversely, when the blood glucose of mice is low, Rg1 can effectively increase the blood glucose value.