Mechanism of structure formation of microbial cellulose during nascent stage

The structure of microbial cellulose (MC) produced by Acetobacter xylinum was studied in presence of Fluorescent Brightener, Direct Blue 1, 14, 15, 53, Direct Red 28, 75 and 79, as probe. X-ray diffraction pattern of the product showed that it was a crystalline complex of dye and cellulose. The product has the structure in which the monomolecular layer of the dye molecule is included between the cellulose sheets corresponding to the ( $ 1\bar{1}0 $ ) planes of microbial cellulose. As a result of dye inclusion, d-spacing of lower angle plane (100) of products becomes 8.0–8.8 Å instead of 6.1 Å of MC. The d-spacing for the higher angle plane must be (010) plane due to stronger van der Waals forces between the pyranose rings which reduced 5.3 Å space of (110) plane of MC to 3.9–4.5 Å in the product. However, cellulose regenerated from FB, DR28 products was cellulose I and IV, respectively, and that from each DB1, 14, 15, 53, DR75 and 79 products was cellulose II. Solid state ¹³C NMR and deuteration-IR showed the product was non-crystalline which was contrasted to X-ray results. The regenerated celluloses were cellulose I_β, IV_I and II, respectively. Thus the structure of the product depends on the characteristics of dye which affects the conformation of cellulose at the nascent stage by the direct interaction with cellulose chains. The different regenerated celluloses as well as different fine structure in the same cellulose allomorph were produced depending mainly on number and position of the sulfonate groups in the dye.     

Photo‐ and pH‐Tunable Multicolor Fluorescent Nanoparticle‐Based Spiropyran‐ and BODIPY‐Conjugated Polymer with Graphene Oxide

We report a stimuli‐responsive fluorescent nanomaterial, based on graphene oxide coupled with a polymer conjugated with photochromic spiropyran (SP) dye and hydrophobic boron dipyrromethane (BODIPY) dye, for application in triggered target multicolor bioimaging. Graphene oxide (GO) was reduced by catechol‐conjugated polymers under mildly alkaline conditions, which enabled to formation of functionalized multicolor graphene nanoparticles that can be induced by irradiation with UV light and by changing the pH from acidic to neutral. Investigation of these nanoparticles by using AFM, fluorescence emission, and in vitro cell and in vivo imaging revealed that they show different tunable colors in bioimaging applications and, more specifically, in cancer‐cell detection. The stability, biocompatibility, and quenching efficacy of this nanocomposite open a different perspective for cell imaging in different independent colors, sequentially and simultaneously.     

Brief survey on phytochemicals to prevent COVID-19

BackgroundThe recent pandemic by COVID-19 is a global threat to human health. The disease is caused by SARS-CoV-2 and the infection rate is increased more quickly than MERS and SARS as their rapid adaptation to varied climatic conditions through rapid mutations. It becomes more severe due to the lack of proper therapeutic drugs, insufficient diagnostic tool, scarcity of appropriate drug, life supporting medical facility and mostly lack of awareness. Therefore, preventive measure is one of the important strategies to control. In this context, herbal medicinal plants received a noticeable attention to treat COVID-19 in Indian subcontinent. Here, 44 Indian traditional plants have been discussed with their novel phytochemicals that prevent the novel corona virus. The basic of SARS-CoV-2, their common way of transmission including their effect on immune and nervous system have been discussed. We have analysed their mechanism of action against COVID-19 following in-silico analysis. Their probable mechanism and therapeutic approaches behind the activity of phytochemicals to stimulate immune response as well as inhibition of viral multiplication discussed rationally. Thus, mixtures of active secondary metabolites/phytochemicals are the only choice to prevent the disease in countries where vaccination will take long time due to overcrowded population density.     

Approaches for Mitigating Microbial Biofilm-Related Drug Resistance: A Focus on Micro- and Nanotechnologies

Biofilms play an essential role in chronic and healthcare-associated infections and are more resistant to antimicrobials compared to their planktonic counterparts due to their (1) physiological state, (2) cell density, (3) quorum sensing abilities, (4) presence of extracellular matrix, (5) upregulation of drug efflux pumps, (6) point mutation and overexpression of resistance genes, and (7) presence of persister cells. The genes involved and their implications in antimicrobial resistance are well defined for bacterial biofilms but are understudied in fungal biofilms. Potential therapeutics for biofilm mitigation that have been reported include (1) antimicrobial photodynamic therapy, (2) antimicrobial lock therapy, (3) antimicrobial peptides, (4) electrical methods, and (5) antimicrobial coatings. These approaches exhibit promising characteristics for addressing the impending crisis of antimicrobial resistance (AMR). Recently, advances in the micro- and nanotechnology field have propelled the development of novel biomaterials and approaches to combat biofilms either independently, in combination or as antimicrobial delivery systems. In this review, we will summarize the general principles of clinically important microbial biofilm formation with a focus on fungal biofilms. We will delve into the details of some novel micro- and nanotechnology approaches that have been developed to combat biofilms and the possibility of utilizing them in a clinical setting.     

Novel Semi-Synthetic Cu (II)–Cardamonin Complex Exerts Potent Anticancer Activity against Triple-Negative Breast and Pancreatic Cancer Cells via Inhibition of the Akt Signaling Pathway

Cardamonin is a polyphenolic natural product that has been shown to possess cytotoxic activity against a variety of cancer cell lines. We previously reported the semi-synthesis of a novel Cu (II)–cardamonin complex (19) that demonstrated potent antitumour activity. In this study, we further investigated the bioactivity of 19 against MDA-MB-468 and PANC-1 cancer cells in an attempt to discover an effective treatment for triple-negative breast cancer (TNBC) and pancreatic cancer, respectively. Results revealed that 19 abolished the formation of MDA-MB-468 and PANC-1 colonies, exerted growth-inhibitory activity, and inhibited cancer cell migration. Further mechanistic studies showed that 19 induced DNA damage resulting in gap 2 (G2)/mitosis (M) phase arrest and microtubule network disruption. Moreover, 19 generated reactive oxygen species (ROS) that may contribute to induction of apoptosis, corroborated by activation of caspase-3/7, PARP cleavage, and downregulation of Mcl-1. Complex 19 also decreased the expression levels of p-Akt and p-4EBP1, which indicates that the compound exerts its activity, at least in part, via inhibition of Akt signalling. Furthermore, 19 decreased the expression of c-Myc in PANC-1 cells only, which suggests that it may exert its bioactivity via multiple mechanisms of action. These results demonstrate the potential of 19 as a therapeutic agent for TNBC and pancreatic cancer.     

Analysis of a “3-(Naphthalen-1-ylimino)indolin-2-one” Compound and Its Antimicrobial Assessment Using Lipid-Based Self-Nanoemulsifying Formulations

In recent years, indole derivatives have acquired conspicuous significance due to their wide spectrum of biological activities—antibacterial, antiviral, and anticonvulsant. This compound is derived from naturally grown plants. Therefore, synthesis of a novel “3-(Naphthalen-1-ylimino)indolin-2-one” compound (2) and its analysis using UPLC systems along with antimicrobial assessment was the aim of the current study. Isatin was used as a parent drug for synthesizing compound (2). Liquid Chromatographic analysis was performed using a C18 BEH column (1.7 μm 2.1 × 50 mm) by UPLC systems. Degradation studies were carried out to see whether acid, base, thermal, and oxidizing agents had any impact on the synthesized molecule in stress conditions (100 °C). A lipid-based self-nanoemulsifying formulation was developed and selectivity, specificity, recovery, accuracy, and precision were measured as part of the UPLC system’s validation process. Antimicrobial studies were conducted using gram-positive and gram-negative bacteria. The standard samples were run with a concentration range of 5.0–100.0 μg/mL using the isocratic mobile phase comprising of methanol/water (70/30 %v/v) at 234 nm; good linearity (R² = 0.9998) was found. The lower limits of detection (LOD) and quantitation (LOQ) of the method were found to be 0.81 μg/mL and 2.5 μg/mL, respectively. The coefficients of variation were found to be less than 2%. The antimicrobial study suggests that compound (2) has a substantial growth effect against gram-negative bacteria. It was successfully synthesized and applied to measure the concentrations in lipid-based dosage form, along with potent antimicrobial activities.     

Transamidation of Amides and Amidation of Esters by Selective N–C(O)/O–C(O) Cleavage Mediated by Air- and Moisture-Stable Half-Sandwich Nickel(II)–NHC Complexes

The formation of amide bonds represents one of the most fundamental processes in organic synthesis. Transition-metal-catalyzed activation of acyclic twisted amides has emerged as an increasingly powerful platform in synthesis. Herein, we report the transamidation of N-activated twisted amides by selective N–C(O) cleavage mediated by air- and moisture-stable half-sandwich Ni(II)–NHC (NHC = N-heterocyclic carbenes) complexes. We demonstrate that the readily available cyclopentadienyl complex, [CpNi(IPr)Cl] (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene), promotes highly selective transamidation of the N–C(O) bond in twisted N-Boc amides with non-nucleophilic anilines. The reaction provides access to secondary anilides via the non-conventional amide bond-forming pathway. Furthermore, the amidation of activated phenolic and unactivated methyl esters mediated by [CpNi(IPr)Cl] is reported. This study sets the stage for the broad utilization of well-defined, air- and moisture-stable Ni(II)–NHC complexes in catalytic amide bond-forming protocols by unconventional C(acyl)–N and C(acyl)–O bond cleavage reactions.     

Quinoline Functionalized Schiff Base Silver (I) Complexes: Interactions with Biomolecules and In Vitro Cytotoxicity,Antioxidant and Antimicrobial Activities

A series of fifteen silver (I) quinoline complexes Q1–Q15 have been synthesized and studied for their biological activities. Q1–Q15 were synthesized from the reactions of quinolinyl Schiff base derivatives L1–L5 (obtained by condensing 2-quinolinecarboxaldehyde with various aniline derivatives) with AgNO₃, AgClO₄ and AgCF₃SO₃. Q1–Q15 were characterized by various spectroscopic techniques and the structures of [Ag(L1)₂]NO₃ Q1, [Ag(L1)₂]ClO₄ Q6, [Ag(L2)₂]ClO₄ Q7, [Ag(L2)₂]CF₃SO₃ Q12 and [Ag(L4)₂]CF₃SO₃ Q14 were unequivocally determined by single crystal X-ray diffraction analysis. In vitro antimicrobial tests against Gram-positive and Gram-negative bacteria revealed the influence of structure and anion on the complexes′ moderate to excellent antibacterial activity. In vitro antioxidant activities of the complexes showed their good radical scavenging activity in ferric reducing antioxidant power (FRAP). Complexes with the fluorine substituent or the thiophene or benzothiazole moieties are more potent with IC₅₀ between 0.95 and 2.22 mg/mL than the standard used, ascorbic acid (2.68 mg/mL). The compounds showed a strong binding affinity with calf thymus-DNA via an intercalation mode and protein through a static quenching mechanism. Cytotoxicity activity was examined against three carcinoma cell lines (HELA, MDA-MB231, and SHSY5Y). [Ag(L2)₂]ClO₄ Q7 with a benzothiazole moiety and [Ag(L4)₂]ClO₄ Q9 with a methyl substituent had excellent cytotoxicity against HELA cells.     

Robust projective lag synchronization in drive-response dynamical networks via adaptive control

This paper investigates the problem of projective lag synchronization behavior in drive-response dynamical networks (DRDNs) with identical and non-identical nodes. An adaptive control method is designed to achieve projective lag synchronization with fully unknown parameters and unknown bounded disturbances. These parameters were estimated by adaptive laws obtained by Lyapunov stability theory. Furthermore, sufficient conditions for synchronization are derived analytically using the Lyapunov stability theory and adaptive control. In addition, the unknown bounded disturbances are also overcome by the proposed control. Finally, analytical results show that the states of the dynamical network with non-delayed coupling can be asymptotically synchronized onto a desired scaling factor under the designed controller. Simulation results show the effectiveness of the proposed method.     

Production of textile filaments from carboxymethylated cellulosic pulps

Cellulose - Textile filaments were fabricated from a solution obtained from carboxymethylated cellulose dissolved in aqueous NaOH solution, by wet spinning in an acid coagulation bath. Spinning is...