Emergence of Gold‐Mesoporous Silica Hybrid Nanotheranostics: Dox‐Encoded,Folate Targeted Chemotherapy with Modulation of SERS Fingerprinting for Apoptosis Toward Tumor Eradication

Strategically fabricated theranostic nanocarrier delivery system is an unmet need in personalized medicine. Herein, this study reports a versatile folate receptor (FR) targeted nanoenvelope delivery system (TNEDS) fabricated with gold core silica shell followed by chitosan–folic acid conjugate surface functionalization by for precise loading of doxorubicin (Dox), resembled as Au@SiO₂‐Dox‐CS‐FA. TNEDS possesses up to 90% Dox loading efficiency and internalized through endocytosis pathway leading to pH and redox‐sensitive release kinetics. The superior FR‐targeted cytotoxicity is evaluated by the nanocarrier in comparison with US Food and Drug Administration (FDA)‐approved liposomal Dox conjugate, Lipodox. Moreover, TNEDS exhibits theranostic features through caspase‐mediated apoptosis and envisages high surface plasmon resonance enabling the nanoconstruct as a promising surface enhanced Raman scattering (SERS) nanotag. Minuscule changes in the biochemical components inside cells exerted by the TNEDS along with the Dox release are evaluated explicitly in a time‐dependent fashion using bimodal SERS/fluorescence nanoprobe. Finally, TNEDS displays superior antitumor response in FR‐positive ascites as well as solid tumor syngraft mouse models. Therefore, this futuristic TNEDS is expected to be a potential alternative as a clinically relevant theranostic nanomedicine to effectively combat neoplasia.     

pH Sensing Properties of Flexible,Bias‐Free Graphene Microelectrodes in Complex Fluids: From Phosphate Buffer Solution to Human Serum

Advances in techniques for monitoring pH in complex fluids can have a significant impact on analytical and biomedical applications. This study develops flexible graphene microelectrodes (GEs) for rapid (<5 s), very‐low‐power (femtowatt) detection of the pH of complex biofluids by measuring real‐time Faradaic charge transfer between the GE and a solution at zero electrical bias. For an idealized sample of phosphate buffer solution (PBS), the Faradaic current is varied monotonically and systematically with the pH, with a resolution of ≈0.2 pH unit. The current–pH dependence is well described by a hybrid analytical–computational model, where the electric double layer derives from an intrinsic, pH‐independent (positive) charge associated with the graphene–water interface and ionizable (negative) charged groups. For ferritin solution, the relative Faradaic current, defined as the difference between the measured current response and a baseline response due to PBS, shows a strong signal associated with ferritin disassembly and the release of ferric ions at pH ≈2.0. For samples of human serum, the Faradaic current shows a reproducible rapid (<20 s) response to pH. By combining the Faradaic current and real‐time current variation, the methodology is potentially suitable for use to detect tumor‐induced changes in extracellular pH.     

Nanoscale zerovalent iron-Sargassum swartzii biocomposites for the removal of malachite green from an aqueous solution

A novel nanoscale zerovalent iron-Sargassum swartzii (nZVI-SS) biocomposite was tested for its ability to remove malachite green from aqueous solutions. Batch equilibrium tests at different pH conditions showed that at pH 10, a maximum removal of 142.85 mg/g was observed according to Langmuir model. Involvement of various functional groups of the biosorbent in preferential biosorption of cationic dye was observed using Fourier transform infrared spectroscopy. Morphological changes occurring on the biocomposite materials were characterized using scanning electron microscopy. Furthermore, temperature and kinetic profiles during the biosorption process were also reported.     

Rapid detection and quantification of soya bean oil and common sugar in bovine milk using attenuated total reflectance–fourier transform infrared spectroscopy

Attenuated total reflectance–Fourier transform infrared spectroscopy, along with chemometrics, were used to detect and quantify soya bean oil (SO) and sugar (CS) adulteration in milk. Bovine milk was artificially adulterated with SO (0.2–2.0%; v/v) and CS (1–10%; w/v) separately. Spectra revealed significant differences in specific wavenumber regions (SO: 1450–1250 cm^?1; CS: 1200–900 cm^?1). Soya bean oil adulteration was best predicted in wavenumber range of 1262–1164 cm^?1, using partial least square regression (coefficient of determination (R²: 0.90 and 0.88 for calibration and validation, respectively). Common sugar adulteration was best predicted in wavenumber range of 1010–910 cm^?1 (R²: 0.99 for calibration and validation) using partial least square.     

Probiotic properties of folate producing Streptococcus thermophilus strains

This study aimed at assessing the probiotic potential of two high folate producing Streptococcus thermophilus strains (RD102 and RD104) isolated from Indian fermented milk products by both in vitro and in vivo tests. These strains were able to survive at pH 2.5 and 2% bile with a good bile salt hydrolase activity, cell surface hydrophobicity and sensitivity to most of the clinically important antibiotics. On evaluation for gastrointestinal transit tolerance these showed a viable count of 5 log cfu mL^?1 and 7 log cfu mL^?1, respectively in simulated gastrointestinal juice of pH 2.0 and 2% bile. During the in vivo feeding trial in mice the strains showed a viable count of about 7 log cfu g^?1 faeces and 6 log cfu g^?1 of large intestine, respectively. These strains were hence observed to possess favorable strain specific probiotic properties and have the potential to be a source of novel probiotics.     

Time‐dependent dosing of Fe2+ for improved lipopeptide production by marine Bacillus megaterium

BACKGROUND: Lipopeptide production is strongly influenced by trace metals. The availability of free Fe²⁺ in the media throughout the process of fermentation was found to be very critical. Since free Fe²⁺ was reported to be sequestered by the lipopeptide as it was produced, intermittent feeding of Fe²⁺ was strategized and optimized for enhanced lipopeptide production by marine Bacillus megaterium in glucose mineral salts medium (GMSM). RESULTS: Studies with the single‐dose Fe²⁺ (0.48 mmol L^?1) supplementation after 8 h of fermentation resulted in lipopeptide concentration of 3.3 ± 0.1 g L^?1. Lipopeptide production was further enhanced to 4.2 ± 0.15 g L^?1 by adopting a multi‐dose Fe²⁺ feeding strategy. The maximum product yield (Y_P/S) of 0.24 ± 0.02 g g^?1 with specific product formation rate (q_p) of 0.124 ± 0.01 g g^?1 h^?1 was achieved when 0.48 mmol L^?1 Fe²⁺ was fed intermittently at different times as per the designed strategy. CONCLUSION: Lipopeptide concentration was improved 4.7‐fold by single‐dosing and 5.8‐fold by multiple dosing of Fe²⁺, when compared with GMSM without Fe²⁺ supplementation. Copyright © 2012 Society of Chemical Industry     

Chromophore‐Linked Substrate (CLS405): Probing Metallo‐β‐Lactamase Activity and Inhibition

Serine‐ and metallo‐β‐lactamases present a threat to the clinical use of nearly all β‐lactam antibiotics, including penicillins, cephalosporins, and carbapenems. Efforts to develop metallo‐β‐lactamase (MBL) inhibitors require suitable screening platforms to allow the rapid determination of β‐lactamase activity and efficient inhibition. Unfortunately, the platforms currently available are not ideal for this purpose. Further progress in MBL inhibitor identification requires inexpensive and widely applicable assays. Herein the identification of an inexpensive and stable chromogenic substrate suitable for use in assays of clinically relevant MBLs is described. (6R,7R)‐3‐((4‐Nitrophenoxy)methyl)‐8‐oxo‐7‐(2‐phenylacetamido)‐5‐thia‐1‐azabicyclo[4.2.0]oct‐2‐ene‐2‐carboxylic acid 5,5‐dioxide (CLS405) was synthesised in a three‐step protocol. CLS405 was then characterised spectroscopically, and its stability and kinetic properties evaluated. With a Δλ_max value of 100 nm between the parent and hydrolysis product, a higher analytical accuracy is possible with CLS405 than with commonly used chromogenic substrates. The use of CLS405 in assays was validated by MBL activity measurements and inhibitor screening that resulted in the identification of N‐hydroxythiazoles as new inhibitor scaffolds for MBLs. Further evaluation of the identified N‐hydroxythiazoles against a panel of clinically relevant MBLs showed that they possess inhibitory activities in the mid‐ to low‐micromolar range. The findings of this study provide both a useful tool compound for further inhibitor identification, and novel scaffolds for the design of improved MBL inhibitors with potential as antibiotics against resistant strains of bacteria.     

Investigation of the Effect of Accelerated Hydrothermal Aging on the Cu Sites in a Cu-BEA Catalyst for NH3-SCR Applications

The influence of hydrothermal aging between 500 and 900 °C for 3 h, on the structure of a Cu-Beta catalyst was studied in this work. The XRD measurements indicated a structural breakdown of the zeolite upon 900 °C hydrothermal aging. This was confirmed from the loss of surface area as measured by BET method. The temperature for the zeolite structure break down was different between the powder bed as opposed to the sample that was washcoated on a cordierite monolith, which was most likely due to slightly different aging conditions and the presence of binders. The strong increase in the intensity of the Cu2p XPS peak indicated that the surface is enriched of copper at higher temperatures due to the zeolite structure collapse. The presence of CuO is usually accompanied by a satellite peak, which was clearly observed at higher binding energies for the catalysts aged at 800 and 900 °C. The XPS results are in good agreement with the UV–Vis experiments, which also point to the formation of copper oxide after high temperature aging.