Rapid targeting and imaging of mitochondria via carbon dots using an amino acid-based amphiphile as a carrier.

Green-fluorescent biocompatible carbon dots with a quantum yield of 40% were successfully synthesized through a solvothermal process and then they are comprehensively characterized. The carbon dots showed a negatively charged surface owing to the presence of carboxylic groups. This negative surface charge hinders the effective targeting and imaging of mitochondria. To address this limitation, a new approach is developed in this study. An amphiphile containing phenylalanine, with a positively charged polar head consisting of triphenylphosphine and a hydrophobic aliphatic tail, was designed, synthesized, purified, and characterized. This amphiphile formed spherical micelle-type nanostructures in an aqueous medium in the aggregated state. Although these nanoprobes lack inherent fluorescence, they exhibited the capability to image mitochondria when their spherical micelle-type nanostructures were decorated with negatively charged fluorescent nanocarbon dots in both cancerous (KB cells) and non-cancerous (CHO cells) cell lines. Notably, carbon dots without the amphiphile failed to penetrate the cell membrane as they exhibited significantly low emission inside the cell. This study extensively explored the cell entry mechanism of the hybrid nanoprobes. The photophysical changes and the interaction between the negatively charged carbon dots and the positively charged nanospheres of the amphiphile were also analyzed in this study.

Stabilization of a Photoradiated Naphthalene Diimide-Based Organic Radical Anion Inside a Peptide-Based Gel Matrix with an Improvement of Optoelectronic Properties.

An amino acid-conjugated naphthalene diimide (NDI)-based highly red fluorescent radical anion has been found in a water medium under the photoradiated condition. This molecule has failed to form the radical anion in the monomeric state; however, the J aggregation in the aqueous medium has ensured the formation of radical anion in the ambient condition after the irradiation of both sunlight and UV light exposure. Electron paramagnetic resonance (EPR) studies clearly suggest the formation of radical anions. Herein, the stability of the radical anion in the aqueous medium is only a few minutes as a small amount of shaking is enough to quench the radical anion in the solution state. Furthermore, the incorporation of this molecule into a peptide-based hydrogel matrix and the consequent photoirradiation have not only helped to develop radical anion in the gel matrix but also increased the enormous stability of the radical anion inside the hydrogel matrix even for 30 days. It is envisaged that the formation of the radical anion within the gel matrix prevents the free movement of the NDI molecules and restricts the diffusion of molecular oxygen in the system, which leads to the stability of the radical anions in the gel. Moreover, the stability of the radical anion within the gel has helped to enhance the conductivity of the hybrid gel to a great extent. Interestingly, the radical anion-containing hybrid hydrogel has shown a potential photoswitching property.

Cationic and amphiphilic peptide-based hydrogels with dual activities as anticancer and antibacterial agents.

The emergence of peptide-based functional biomaterials is on the rise. To fulfil this purpose, a series of amphiphilic peptides, such as H2N-X-Met-Phe-C12H25, where X = L-lysine (CP1), X = L-histidine (CP2), and X = L-leucine (CP3), have been designed, synthesised, purified and fully characterised. Herein, we reported peptide-based supramolecular hydrogels with antibacterial and anticancer activities. An attempt has been made to investigate the antibacterial properties of these peptide-based hydrogels against Gram-positive (S. aureus and B. subtilis) and Gram-negative (E. coli and P. aeruginosa) bacteria. Investigations show that the L-lysine containing gelator, CP1, is active against both Gram-positive and Gram-negative bacteria and the L-histidine containing gelator, CP2, selectively inhibits the growth of Gram-negative bacteria. Interestingly, the L-leucine containing gelator, CP3, does not show any antibacterial properties. Moreover, the L-lysine containing gelator exhibits the best potency. Generation of reactive oxygen species (ROS) is a probable way to damage the bacterial membrane. To explore the cytotoxic properties and to determine the efficacy of the synthesized compounds in inhibiting cell viability, a comprehensive investigation was performed using three distinct cell lines: MDA-MB-231 (human triple-negative breast cancer), MDA-MB-468 (human triple-negative breast cancer) and HEK 293 (human embryonic kidney). Remarkably, the results of our study revealed a substantial cytotoxic impact of these peptide gelators on the MDA-MB-231 and MDA-MB-468 cell lines in comparison to the HEK 293 cells. Caspase 3/7 activity is the possible mechanistic path to determine the apoptotic rates of the cell lines. This finding emphasizes the promising potential of these peptide-based gelators in targeting and suppressing the growth of human triple negative breast cancer cells, while showing non-cytotoxicity towards non-cancerous HEK 293 cells. In a nutshell, these peptide-based materials are coming to light as next generation biomaterials.

Carbon Dot as Visible-Light Photoredox Catalysts for a Myriad of Organic Transformations.

Metal-free catalysts for various organic transformations are of high demand now. In this study, we present a new carbon dot as an efficient metal-free nanophotocatalyst for carrying out a series of organic bond formation reactions. Using a single photocatalyst carbon dot, Csp2-Csp2, Csp2-B, Csp2-S, Csp2-Se, and C-P bond formation reactions were performed with a high yield of the corresponding products. Moreover, Csp2-H activation of the aromatic ring was achieved by merging the carbon dot photocatalyst with a transition metal. Interestingly, these carbon nanodot-based catalysts show good recyclability a few times without any significant loss of catalytic activity. The development of catalytic systems based on carbon dots has its merits vested in the advantageous properties of this nanomaterial, such as a robust chemical nature and cheap cost of preparation. This report demonstrates that a carbon dot indeed holds the potential to replace expensive metal-based catalysts as well as organic dyes in five different photoredox reactions.

Effect of molar ratio and concentration on the rheological properties of two-component supramolecular hydrogels: tuning of the morphological and drug releasing behaviour.

Self-assembled supramolecular hydrogels offer great potential as biomaterials and drug delivery systems. Specifically, peptide-based multicomponent hydrogels are promising materials due to their advantage that their mechanical and physical properties can be tuned to enhance their functionalities and broaden their applications. Herein, we report two-component assembly and formation of hydrogels containing inexpensive complementary anionic, BUVV-OH (A), and cationic, KFFC12 (B), peptide amphiphiles. Individually, neither of these components formed a hydrogel, while mixtures with compositions 1 : 1, 1 : 2, and 2 : 1 (molar ratio) as A : B show hydrogel formation (Milli-Q water, at pH = 6.79). These hydrogels displayed a good shear-thinning behaviour with different mechanical stabilities and nano-fibrous network structures. The 1 : 1 hydrogel shows good cell viability for human embryonic kidney (HEK-293) cells and CHO cells indicating its non-cytotoxicity. The biocompatible, thixotropic 1 : 1 hydrogel with a nanofiber network structure shows the highest mechanical strength with a storage modulus of 3.4 × 103 Pa. The hydrogel is able to encapsulate drugs including antibiotics amoxicillin and rifampicin, and anticancer drug doxorubicin, and it exhibits sustainable release of 76%, 70%, and 81% respectively in vitro after 3 days. The other two mixtures (composition 1 : 2 and 2 : 1) are unable to form a hydrogel when they are loaded with these drugs. Interestingly, it is noticed that with an increase in concentration, the mechanical strength of a 1 : 1 hydrogel is significantly enhanced, showing potential that may act as a scaffold for tissue engineering. The two-component gel offers tunable mechanical properties, thixotropy, injectability, and biocompatibility and has great potential as a scaffold for sustained drug release and tissue engineering.

Histidine-Containing Amphiphilic Peptide-Based Non-Cytotoxic Hydrogelator with Antibacterial Activity and Sustainable Drug Release.

A histidine-based amphiphilic peptide (P) has been found to form an injectable transparent hydrogel in phosphate buffer solution over a pH range from 7.0 to 8.5 with an inherent antibacterial property. It also formed a hydrogel in water at pH = 6.7. The peptide self-assembles into a nanofibrillar network structure which is characterized by high-resolution transmission electron microscopy, field-emission scanning electron microscopy, atomic force microscopy, small-angle X-ray scattering, Fourier-transform infrared spectroscopy, and wide-angle powder X-ray diffraction. The hydrogel exhibits efficient antibacterial activity against both Gram-positive bacteria Staphylococcus aureus (S. aureus) and Gram-negative bacteria Escherichia coli (E. coli). The minimum inhibitory concentration of the hydrogel ranges from 20 to 100 µg/mL. The hydrogel is capable of encapsulation of the drugs naproxen (a non-steroidal anti-inflammatory drug), amoxicillin (an antibiotic), and doxorubicin, (an anticancer drug), but, selectively and sustainably, the gel releases naproxen, 84% being released in 84 h and amoxicillin was released more or less in same manner with that of the naproxen. The hydrogel is biocompatible with HEK 293T cells as well as NIH (mouse fibroblast cell line) cells and thus has potential as a potent antibacterial and drug releasing agent. Another remarkable feature of this hydrogel is its magnification property like a convex lens.

Metal ion-induced assembly of dipeptide-attached perylenediimide for fluorometric "turn on" detection of biologically important small molecule.

A dipeptide-appended perylenediimide (PDI-CFF) fluorescent molecule was designed, synthesized, and characterized. Though the molecule does not dissolve in any individual solvent, it dissolves well in an organic/water mixed solvent system such as tetrahydrofuran/water. This new fluorescent molecule was self-assembled in a tetrahydrofuran/water mixture to form both nanofibrous network structures and a nano ring structure. It has shown nanofibril morphology by the interactions with ferric ions (PDI-CFF/Fe3+ system) with diminishing fluorescent property. Interestingly, L-ascorbic acid (LAA) interacts with the PDI-CFF/Fe3+ system, showing turn-on fluorescence. Another interesting feature is that the minimum detection limits for Fe3+ ions and LAA are at the submicromolar levels of 6.2 × 10-8 and 3 × 10-8  M, respectively. Moreover, the fluorescent (10 µM) signals can be monitored by the naked eye under handheld UV lamp irradiation at 365 nm, and this is very convenient for the real application. In this study, the molecule offers the opportunity for processing these sequential fluorescence responses in order to fabricate a implication logic gate that includes NOT, AND, and OR simple logic gates using chemical stimuli (ferric ions and LAA) as inputs and fluorescence emission at 536 nm as output. The detailed mechanism of interactions of Fe3+ with PDI-CFF and LAA with the PDI-CFF/Fe3+ system is vividly studied by using Fourier transform infrared (FT-IR) analysis and fluorescence. Moreover, this new molecule was reusable for several times without significant loss of its activity. The construction of logic gates using biologically important molecules/ions holds future promise for the design and development of new bio-logic gates.

Surface modification of carbon dots via peptide covalent conjugation.

Surface modification of carbon dots via covalent conjugation with a dipeptide resulted in a dramatic change in the fluorescence emission from green to red. The hydrophobic peptide units linked to the surface of the modified carbon dots helped them to aggregate by generating a nanodot-fabricated nanofibrous network. This nanofibrous network showed excellent electrical conductivity and photo-switching behavior, better than those of the non-aggregated dots.

BCA101 Is a Tumor-Targeted Bifunctional Fusion Antibody That Simultaneously Inhibits EGFR and TGFß Signaling to Durably Suppress Tumor Growth.

The EGFR and TGFß signaling pathways are important mediators of tumorigenesis, and cross-talk between them contributes to cancer progression and drug resistance. Therapies capable of simultaneously targeting EGFR and TGFß could help improve patient outcomes across various cancer types. Here, we developed BCA101, an anti-EGFR IgG1 mAb linked to an extracellular domain of human TGFßRII. The TGFß "trap" fused to the light chain in BCA101 did not sterically interfere with its ability to bind EGFR, inhibit cell proliferation, or mediate antibody-dependent cellular cytotoxicity. Functional neutralization of TGFß by BCA101 was demonstrated by several in vitro assays. BCA101 increased production of proinflammatory cytokines and key markers associated with T-cell and natural killer-cell activation, while suppressing VEGF secretion. In addition, BCA101 inhibited differentiation of naïve CD4+ T cells to inducible regulatory T cells (iTreg) more strongly than the anti-EGFR antibody cetuximab. BCA101 localized to tumor tissues in xenograft mouse models with comparable kinetics to cetuximab, both having better tumor tissue retention over TGFß "trap." TGFß in tumors was neutralized by approximately 90% in animals dosed with 10 mg/kg of BCA101 compared with 54% in animals dosed with equimolar TGFßRII-Fc. In patient-derived xenograft mouse models of head and neck squamous cell carcinoma, BCA101 showed durable response after dose cessation. The combination of BCA101 and anti-PD1 antibody improved tumor inhibition in both B16-hEGFR-expressing syngeneic mouse models and in humanized HuNOG-EXL mice bearing human PC-3 xenografts. Together, these results support the clinical development of BCA101 as a monotherapy and in combination with immune checkpoint therapy. SIGNIFICANCE: The bifunctional mAb fusion design of BCA101 targets it to the tumor microenvironment where it inhibits EGFR and neutralizes TGFß to induce immune activation and to suppress tumor growth.

Tolerance effect of a shock-free atmospheric plasma on human skin.

In this work, a shock-free argon-fed plasma plume was generated by a variable-frequency power supply and the discharge characteristics were investigated from the voltage and current waveforms between 72 and 92 kHz frequencies. The higher electron temperature dominates the plasma chemical process and the average plasma temperature is about 30 â„ƒ under these conditions. The influence of non-thermal atmospheric plasma plume length and plume temperature on Ar gas flow is optimized at 7 sL/min. The average charge accumulation on the plume tip area and the dependence of flow rate on the plasma irradiation area were also explored. This atmospheric pressure plasma jet (APPJ) has been proposed for human-skin irradiation on different areas (even on the tongue) owing to its less painful, tingling and burning effect. Optical emission spectroscopy (OES) confirmed the presence of excited argon with reactive nitrogen (RNS) and oxygen species (ROS). This study contributes to a better understanding of non-thermal plasma effects on the human body which may find prospects for disinfection and prevention of different diseases during the current pandemic time. Supplementary Information: The online version contains supplementary material available at 10.1007/s00339-022-06022-w.

Amino acid containing amphiphilic hydrogelators with antibacterial and antiparasitic activities.

Nanoscale self-assembly of peptide constructs represents a promising means to present bioactive motifs to develop new functional materials. Here, we present a series of peptide amphiphiles which form hydrogels based on ß-sheet nanofibril networks, several of which have very promising anti-microbial and anti-parasitic activities, in particular against multiple strains of Leishmania including drug-resistant ones. Aromatic amino acid based amphiphilic supramolecular gelators C14-Phe-CONH-(CH2)n-NH2 (n = 6 for P1 and n = 2 for P3) and C14-Trp-CONH-(CH2)n-NH2 (n = 6 for P2 and n = 2 for P4) have been synthesized and characterized, and their self-assembly and gelation behaviour have been investigated in the presence of ultrapure water (P1, P2, and P4) or 2% DMSO(v/v) in ultrapure water (P3). The rheological, morphological and structural properties of the gels have been comprehensively examined. The amphiphilic gelators (P1 and P3) were found to be active against both Gram-positive bacteria B. subtilis and Gram-negative bacteria E. coli and P. aeruginosa. Interestingly, amphiphiles P1 and P3 containing an L-phenylalanine residue show both antibacterial and antiparasitic activities. Herein, we report that synthetic amphiphiles with an amino acid residue exhibit a potent anti-protozoan activity and are cytotoxic towards a wide array of protozoal parasites, which includes Indian varieties of Leishmania donovani and also kill resistant parasitic strains including BHU-575, MILR and CPTR cells. These gelators are highly cytotoxic to promastigotes of Leishmania and trigger apoptotic-like events inside the parasite. The mechanism of killing the parasite is shown and these gelators are non-cytotoxic to host macrophage cells indicating the potential use of these gels as therapeutic agents against multiple forms of leishmaniasis in the near future.

Organic Mixed Ion-Electron Conductivity in Polymer Hybrid Systems.

Recently, organic materials with mixed ion/electron conductivity (OMIEC) have gained significant interest among research communities all over the world. The unique ability to conduct ions and electrons in the same organic material adds to their use in next generation electrochemical, biotechnological, energy generation, energy storage, electrochromic, and sensor devices. Semiconducting conjugated polymers are well-known OMIECs due to their feasibility for both ion and electron transport in the bulk region. In this mini-review, we have shed light on conjugated polymers with ionic pendent groups, block copolymers of electronically and ionic conducting polymers, polymer electrolytes, blends of conjugated polymers with polyelectrolyte/polymer electrolytes; blends of conducting polymer with small organic molecules including conducting polymer-peptide conjugates; and blends of nonconjugated polymers as mixed conducting systems. These systems not only include the well-studied OMEIC systems, but also include some new systems where the OMEIC property has been predicted from the typical current-voltage (I-V) plots. The conduction mechanism of ions and electrons, ion-electron coupling, directionality, and dimensionality of these OMEIC materials are discussed in brief. The different properties of OMEIC materials and their applications in diverse fields like energy, electrochromic, biotechnology, sensing, and so forth are enlightened together with the perspective for future improvement of OMEIC materials.

Effects of variable deceleration periods on Rayleigh-Taylor instability with acceleration reversals.

The dynamics of an interfacial flow that is initially Rayleigh-Taylor unstable but becomes statically stable for some intermediate period due to the reversal of the externally imposed acceleration field is studied. We discuss scenarios that consider both single and double-acceleration reversals. The accel-decel (AD) case consists of a single reversal imposed at an instant after the constant acceleration instability has entered a self-similar regime. The layer of mixed fluid ceases to grow upon acceleration reversal, and the dominant mechanics are due to internal wave oscillations. Variation of mass flux and the Reynolds stress anisotropy is observed due to the action of the internal waves. A second reversal of the AD case that is termed as accel-decel-accel, ADA is then explored; the response of the mixing layer is shown to depend strongly on the duration and the periodicity of the Reynolds stress anisotropy of the mixing layer during the deceleration period. We explore the effect of this variable deceleration period after the second acceleration reversal where the flow once again becomes Rayleigh-Taylor unstable based on metrics that include the integral mixing-layer width, bubble and spike amplitudes, mass flux, Reynolds stress anisotropy tensor, and the molecular mixing parameter.

Yellow-Emitting Carbon Dots for Selective Fluorescence Imaging of Lipid Droplets in Living Cells.

This study shows a one-pot preparation of carbon dots by a solvothermal method in ethylene glycol. The carbon dots show yellow-colored fluorescence emission in water. The carbon dots showed distinct preference to be present in the hydrophobic environment which was evident from their efficient transfer from aqueous phase to organic phase. They were also found to locate themselves in the vesicle bilayer and micelle core. This inherent lipophilic character of these carbon dots has been successfully utilized for the selective imaging of lipid droplets inside the living cells. The selective imaging of lipid droplets was confirmed by similar staining patterns with other staining dyes and the starvation study.

Dorsalis pedis artery thrombosis in an elite rugby player: an unusual cause of pedal claudication in a high-risk ankle.

Vascular thrombosis in young elite athletes is uncommon, usually affecting calf veins and arteries beyond the knee joint. Arterial thrombosis, especially in the dorsalis pedis artery, is very rare without premature atherosclerosis or trauma. Its clinical presentation with progressive claudication of insidious onset is nonspecific and overlaps with the symptoms of deep peroneal nerve compression as a part of anterior ankle impingement, a more common entity in athletes. Ultrasound can evaluate pedal claudication in athletes differentiating vascular and neural causes expediting diagnosis, management and, in turn, return to play. Furthermore, imaging-Doppler ultrasound and MR angiography in particular-plays a vital role in the evaluation of potential aetiology and evolution (i.e., collateral development and recanalization) of the occluded vessel. We present a case of dorsalis pedis artery thrombosis with both MRI and ultrasound findings in a professional rugby player who had no systemic comorbidity, but numerous previous surgical interventions around the ankle joint in both the remote and recent past, putting the adjacent DPA at increased risk for developing thrombosis. In this high-risk ankle, the dorsalis pedis thrombosis may be iatrogenic or due to sports-related, arterial wall injury with superimposed thrombosis.

The number of tree species on Earth.

One of the most fundamental questions in ecology is how many species inhabit the Earth. However, due to massive logistical and financial challenges and taxonomic difficulties connected to the species concept definition, the global numbers of species, including those of important and well-studied life forms such as trees, still remain largely unknown. Here, based on global ground-sourced data, we estimate the total tree species richness at global, continental, and biome levels. Our results indicate that there are ∼73,000 tree species globally, among which ∼9,000 tree species are yet to be discovered. Roughly 40% of undiscovered tree species are in South America. Moreover, almost one-third of all tree species to be discovered may be rare, with very low populations and limited spatial distribution (likely in remote tropical lowlands and mountains). These findings highlight the vulnerability of global forest biodiversity to anthropogenic changes in land use and climate, which disproportionately threaten rare species and thus, global tree richness.

ARTEMIN Promotes Oncogenicity and Resistance to 5-Fluorouracil in Colorectal Carcinoma by p44/42 MAPK Dependent Expression of CDH2.

ARTEMIN (ARTN), one of the glial-cell derived neurotrophic factor family of ligands, has been reported to be associated with a number of human malignancies. In this study, the enhanced expression of ARTN in colorectal carcinoma (CRC) was observed; the expression of ARTN positively correlated with lymph node metastases and advanced tumor stages and predicted poor prognosis. Forced expression of ARTN in CRC cells enhanced oncogenic behavior, mesenchymal phenotype, stem cell-like properties and tumor growth and metastasis in a xenograft model. These functions were conversely inhibited by depletion of endogenous ARTN. Forced expression of ARTN reduced the sensitivity of CRC cells to 5-FU treatment; and 5-FU resistant CRC cells harbored enhanced expression of ARTN. The oncogenic functions of ARTN were demonstrated to be mediated by p44/42 MAP kinase dependent expression of CDH2 (CADHERIN 2, also known as N-CADHERIN). Inhibition of p44/42 MAP kinase activity or siRNA mediated depletion of endogenous CDH2 reduced the enhanced oncogenicity and chemoresistance consequent to forced expression of ARTN induced cell functions; and forced expression of CDH2 rescued the reduced mesenchymal properties and resistance to 5-FU after ARTN depletion. In conclusion, ARTN may be of prognostic and theranostic utility in CRC.

Tuning of the optoelectronic properties of peptide-appended core-substituted naphthalenediimides: the role of self-assembly of two positional isomers.

This study demonstrates how the self-assembly pattern of two different and isomeric peptide-appended core-substituted naphthalenediimides (NDIs) affects the modulation of their optoelectronic properties. Two isomeric peptide-attached NDIs were synthesized, purified and characterized. Interchanging the position of attachment of the peptide units and the alkyl chains in the NDI has altered the respective self-assembling patterns of these isomeric molecules in the aggregated states. The isomer having a peptide moiety in the core position and the alkyl chain in the imide position (compound N1) forms face to face stacking or 'H' aggregates in aliphatic solvents including n-hexane, and n-decane, whereas compound N2, in which the peptide moiety is at the imide position and the alkyl chain is attached at the core position of NDI exhibits edge to edge stacking or J aggregates under the same conditions as it is evident from their UV-vis studies. The H aggregated species (obtained from N1) show inter-connected nanofibers, whereas the J aggregated species (obtained from N2) exhibit the morphology of helical nanoribbons. FT-IR and X-ray diffraction studies are in favor of the same aggregation behavior. The individual packing patterns of these two peptide-based isomers have a direct impact on their respective electrical conductivity. Interestingly, the H aggregated species shows 100 times greater current conductivity than that of the J aggregate. Moreover, it is only the H aggregated species that exhibits a photocurrent, and no such photocurrent response is observed with the J aggregates. Computational studies also support that different types of aggregation patterns are formed by these two isomeric molecules in the same solvent system. This unique example of tuning of optoelectronic behavior holds future promise for the development of new peptide-conjugated π-functional materials.

Solvent-Directed Transformation of the Self-assembly and Optical Property of a Peptide-Appended Core-Substituted Naphthelenediimide and Selective Detection of Nitrite Ions in an Aqueous Medium.

This study vividly displays the different self-assembling behavior and consequent tuning of the fluorescence property of a peptide-appended core-substituted naphthalenediimide (N1) in the aliphatic hydrocarbon solvents (n-hexane/n-decane/methyl cyclohexane) and in an aqueous medium within micelles. The N1 is highly fluorescent in the monomeric state and self-aggregates in a hydrocarbon solvent, exhibiting "H-type" or "face-to-face" stacking as indicated by a blue shift of absorption maxima in the UV-vis spectrum. In the H-aggregated state, the fluorescence emission of N1 changes to green from the yellow emission obtained in the monomeric state. In the presence of a micelle-forming surfactant, cetyl trimethylammonium bromide (CTAB), the N1 is found to be dispersed in a water medium. Interestingly, upon encapsulation of N1 into the micelle, the molecule alters its self-assembling pattern and optical property compared to its behavior in the hydrocarbon solvent. The N1 exhibits "edge-to-edge" stacking or J aggregates inside the micelle as indicated by the UV-vis spectroscopic study, which shows a red shift of the absorption maxima compared to that in the monomeric state. The fluorescence emission also differs in the water medium with the NDI derivative exhibiting red emission. FT-IR studies reveal that all amide NHs of N1 are hydrogen-bonded within the micelle (in the J-aggregated state), whereas both non-bonding and hydrogen-bonding amide NHs are present in the H-aggregated state. This is a wonderful example of solvent-mediated transformation of the aggregation pattern (from H to J) and solvatochromism of emission over a wide range from green in the H-aggregated state to yellow in the monomeric state and orangish-red in the J-aggregated state. Moreover, the J aggregate has been successfully utilized for selective and sensitive detection of nitrite ions in water even in the presence of other common anions (NO3-, SO42-, HSO4-, CO32-, and Cl-).

Network theoretic analysis of JAK/STAT pathway and extrapolation to drugs and viruses including COVID-19.

Whenever some phenomenon can be represented as a graph or a network it seems pertinent to explore how much the mathematical properties of that network impact the phenomenon. In this study we explore the same philosophy in the context of immunology. Our objective was to assess the correlation of "size" (number of edges and minimum vertex cover) of the JAK/STAT network with treatment effect in rheumatoid arthritis (RA), phenotype of viral infection and effect of immunosuppressive agents on a system infected with the coronavirus. We extracted the JAK/STAT pathway from Kyoto Encyclopedia of Genes and Genomes (KEGG, hsa04630). The effects of the following drugs, and their combinations, commonly used in RA were tested: methotrexate, prednisolone, rituximab, tocilizumab, tofacitinib and baricitinib. Following viral systems were also tested for their ability to evade the JAK/STAT pathway: Measles, Influenza A, West Nile virus, Japanese B virus, Yellow Fever virus, respiratory syncytial virus, Kaposi's sarcoma virus, Hepatitis B and C virus, cytomegalovirus, Hendra and Nipah virus and Coronavirus. Good correlation of edges and minimum vertex cover with clinical efficacy were observed (for edge, rho = - 0.815, R2 = 0.676, p = 0.007, for vertex cover rho = - 0.793, R2 = 0.635, p = 0.011). In the viral systems both edges and vertex cover were associated with acuteness of viral infections. In the JAK/STAT system already infected with coronavirus, maximum reduction in size was achieved with baricitinib. To conclude, algebraic and combinatorial invariant of a network may explain its biological behaviour. At least theoretically, baricitinib may be an attractive target for treatment of coronavirus infection.