An Approach for the Selective Detection of Nitric Oxide in Biological Systems: An in vitro and in vivo Perspective

A naphthalimide‐based fluorescent probe, LyNP‐NO , was designed and synthesized for the selective detection of exogenously and endogenously generated nitric oxide (NO) in C6 glial cells. In addition, LyNP‐NO was also explored for monitoring endogenous NO levels in rat hippocampus at various tissue depths by stimulating the brain with N‐methyl‐d ‐aspartate (NMDA).     

Development of Miniature Solid Contact Ion Selective Electrodes for in situ Instrumentation

Using a standardized miniature format ion selective electrode, five different carbon based solid contact materials, including a novel commercially available graphene oxide assisted carbon nanotube dispersion (Flexiphene^TM), were compared. The electromotive force (EMF) response, stability, and behavior following storage was evaluated. Bulk resistance for the novel graphene oxide/carbon nanotube (GO‐CNT) based ISE was observed to be 0.09±0.03 MΩ, which is two orders of magnitude lower than reported for either component in isolation. The results for previously described solid contact materials are in general agreement with the literature, and the tradeoffs between solid contact layer material choices are discussed. Performance of GO‐CNT solid contact ion selective electrodes were then evaluated in a 3D‐printed fluidic array to determine their suitability for future in situ instruments.     

Antileishmanial Drug Miltefosine‐dsDNA Interaction in situ Evaluation with a DNA‐Electrochemical Biosensor

Leishmaniasis is one of the most important parasitic neglected disease. The electrochemical evaluation of the antileishmanial drug miltefosine‐dsDNA interaction was investigated in incubated solutions and using dsDNA‐electrochemical biosensors, following the changes in the oxidation peaks of guanosine and adenosine residues, and the occurrence of the free guanine residues, electrochemical signal. The electrochemical behaviour of miltefosine was also investigated, at a glassy carbon electrode, using cyclic, differential pulse and square wave voltammetry and no electrochemical redox processes were observed. The interaction mechanism of miltefosine‐dsDNA occurs in two ways: independent of the dsDNA sequence, and leading to the condensation/aggregation of DNA strands, producing a rigid miltefosine‐dsDNA complex structure, and a preferential interaction between the guanine hydrogen atoms in the C−G base pair and miltefosine, causing the release of guanine residues detected on the electrode surface. Miltefosine did not induce oxidative damage to DNA in the experimental conditions used.     

Genetically Encoding a Lipidated Amino Acid for Extension of Protein Half‐Life in vivo

Protein therapeutics are increasingly used to treat various diseases, yet they often suffer from short serum half‐lives. An emerging strategy to extend lifetime in vivo is to attach fatty acids onto proteins to increase their binding to human serum albumin (HSA). Herein, the genetic encoding of ?‐N‐heptanoyl‐l ‐lysine (HepoK) is reported, which introduces a fatty‐acid‐containing amino acid into proteins with exquisite site‐specificity and homogeneity, overcoming issues associated with existing chemical conjugation methods. The expression in E .coli and purification of HepoK‐incorporated glucagon‐like peptide‐1 (GLP1) is demonstrated. GLP1(HepoK) showed stronger binding to HSA than GLP1(WT), without impairing the stimulation of the GLP1 receptor in cells. Moreover, GLP1(HepoK) decreased blood glucose level to the same level as GLP1(WT) in mice, showing longer‐lasting effects than GLP1(WT). HepoK incorporation will also be useful for investigating the function of protein lipidation.     

First Order Derivative Voltammetry on the in situ Surfactant Modified Electrode for Naringin Quantification

Carboxylated multi‐walled carbon nanotubes based glassy carbon electrodes (MWNT‐COOH/GCE) modified in situ with surfactants (sodium dodecyl sulfate (SDS), cetylpyridinium bromide (CPB) and Triton X100) have been tested for the naringin determination. The effect of surfactant nature and concentration on the voltammetric characteristics of naringin has been evaluated. Anionic 100 μM SDS shows the highest 2.7‐fold increase of the oxidation currents in comparison to MWNT‐COOH/GCE. The irreversible electrooxidation of naringin is surface‐controlled process with the one electron and one proton transfer. Under conditions of first order derivative linear sweep voltammetry in Britton‐Robinson buffer (BRB) pH 8.0, the analytical ranges of 0.75–25 and 25–100 μM with the LOD and LOQ of 0.14 and 0.46 μM, respectively, have been obtained. The electrode response is selective in the presence of ascorbic, gallic and p‐coumaric acids as well as quercetin, catechin and rutin. The method has been applied for the naringin quantification in grapefruit juices.     

Recent Advances and Developments of in vitro Evaluation of Heterocyclic Moieties on Cancer Cell Lines

Besides worthy development in cancer therapy, cancer is still one of the leading causes of death, worldwide. The future burden of cancer will probably be even larger because people are adopting poor lifestyles with poor diet, frequently smoking and less physical activity. The effective anticancer drugs having efficacy and selectivity with low toxicity is still a challenge for the scientific fraternity. The advances in the cancer study have its origin on the availability of different types of experimental model systems that review the various forms of this disease. Cell lines emerge as a feasible alternative for anticancer activities, being at the same time easy to manipulate and molecularly characterize. Heterocycles are key structural components of many of the anti‐cancer drugs available on the market today. Indeed, of the novel molecular anti‐cancer agents approved by the FDA between 2010 and 2017, almost two‐thirds contained heterocyclic rings within their structures. This review summarizes and provides updated literature on heterocyclic compounds using various cancer cell lines reported during the period of 2014–2017 together with the structure‐activity relationships.     

An in situ Dynamic Continuum of Supramolecular Phosphoglycopeptides Enables Formation of 3D Cell Spheroids

Higher‐order assemblies of proteins, with a structural and dynamic continuum, is an important concept in biology, but these insights have yet to be applied in designing biomaterials. Dynamic assemblies of supramolecular phosphoglycopeptides (sPGPs) transform a 2D cell sheet into 3D cell spheroids. A ligand–receptor interaction between a glycopeptide and a phosphopeptide produces sPGPs that form nanoparticles, which transform into nanofibrils upon partial enzymatic dephosphorylation. The assemblies form dynamically and hierarchically in situ on the cell surface, and interact with the extracellular matrix molecules and effectively abolish contact inhibition of locomotion (CIL) of the cells. Integrating molecular recognition, catalysis, and assembly, these active assemblies act as a dynamic continuum to disrupt CIL, thus illustrating a new kind of biomaterial for regulating cell behavior.     

Dual Fluorescent‐ and Isotopic‐Labelled Self‐Assembling Vancomycin for in vivo Imaging of Bacterial Infections

The increase of bacterial resistance demands rapid and accurate diagnosis of bacterial infections. Biosurface‐induced supramolecular assembly for diagnosis and therapy has received little attention in detecting bacterial infections. Herein we present a dual fluorescent‐nuclear probe based on self‐assembly of vancomycin (Van) on Gram‐positive bacteria for imaging bacterial infection. A Van‐ and rhodamine‐modified peptide derivative (Rho‐FF‐Van), as the imaging agent, binds to the terminal peptide of the methicillin‐resistant staphylococcus aureus (MRSA) and self‐assembles to form nanoaggregates on the surface of MRSA . In an in vivo myositis model, Rho‐FF‐Van results in a significant increased fluorescence signal at the MRSA infected site. Radiolabeled with iodine‐125, Rho‐FF‐Van shows strong radioactive signal in the MRSA ‐infected lungs in a murine model. This novel dual fluorescent and nuclear probe promises a new way for in vivo imaging of bacterial infections.