Current Scenario of Regenerative Medicine: Role of Cell, Scaffold and Growth Factor

Impairment of the clinical tissue-implantation is due to the lack of a suitable organ donor and immunogenic rejection, which leads to the cause for the enormous loss of human life. The introduction of artificial regeneration of tissues by Langer and Vacanti in 1993, has revolutionized in the field of surgical organ transplantation, to alleviate the problem of tissue injury-related death. There is no doubt that the term “regenerative medicine” to open a new space of tissue reconstruction, but the complications that arise due to the proper machinery of the cell, supporting biomaterials and growth factors has yet to be resolved to expand its application in a versatile manner. The chapter would provide a significant overview of the artificial tissue regeneration while a triangular relationship between cells, matrixes, and growth factors should be established mentioning the necessity of biomedical tools as an alternative to organ transplantation

Hyaluronic Acid Derivatives for Targeted Cancer Therapy

Targeted therapeutics are considered next generation cancer therapy because they overcome many limitations of traditional chemotherapy. Cancerous cells may be targeted by various hyaluronic acid modified nanovehicles that kill these cells. Particularly, hyaluronic acid and its derivatives bind with high affinity to cell surface protein, CD44 enriched tumor cells. Moreover, these molecules have the added advantage of being biocompatible and biodegradable, and may be conjugated with a variety of drugs and drug carriers for developing various formulations as anti-cancer therapies such as nanogels, self-assembled and metallic nanoparticulates. In this chapter, we have covered various aspects of hyaluronic acid-modified delivery systems including strategies for synthesis, characterization, and biocompatibility. Next, the use of hyaluronic acid-modified systems as anti-cancer therapies is discussed. Finally, the delivery of small molecules, and other pharmaceutical agents are also elaborated in this chapter

Antibacterial efficacy of Jackfruit rag extract against clinically important pathogens and validation of its antimicrobial activity in Shigella dysenteriae infected Drosophila melanogaster infection model

513-522Exploration of alternative sources of antibacterial compounds is an important and possibly an effective solution to the current challenges in antimicrobial therapy. Plant derived wastes may offer one such alternative. Here, we investigated the antibacterial property of extract derived from a part of the Jackfruit (Artocarpus heterophyllus Lam.) called ‘rag’, generally considered as fruit waste. Morpho-physical characterization of the Jackfruit rag extract (JFRE) was performed using Gas-chromatography, where peaks indicative of furfural; pentanoic acid; and hexadecanoic acid were observed. In vitro biocompatibility of JFRE was performed using the MTT assay, which showed comparable cellular viability between extract-treated and untreated mouse fibroblast cells. Agar well disc diffusion assay exhibited JFRE induced zones of inhibition for a wide variety of laboratory and clinical strains of Gram-positive and Gram-negative bacteria. Analysis of electron microscope images of bacterial cells suggests that JFRE induces cell death by disintegration of the bacterial cell wall and precipitating intracytoplasmic clumping. The antibacterial activity of the JFREs was further validated in vivo using Shigella dysenteriae infected fly model, where JFRE pre-fed flies infected with S. dysenteriae had significantly reduced mortality compared to controls. JFRE demonstrates broad antibacterial property, both in vitro and in vivo, possibly by its activity on bacterial cell wall

Synthesis, characterization and structure of the salicylate salt of [RuH(terpy)(PPh₃)₂]⁺(terpy = 2,2′ : 6′,2″-terpyridine)

The complex [RuH(terpy)(PPh₃)₂][C₇H₅O₃]1 has been synthesised from 2,2′ : 6′,2″-terpyridine (terpy) and [RuH(C₇H₅O₃)(PPh₃)₃] where C₇H₅O₃ is salicylate. It shows ν(RuH) at 1960 cm^–1 and a hydridic ¹H triplet at δ–6.30, J= 26.2 Hz. The crystal structure of 1 has been determined: space group Pnam, a= 14.705(7), b= 15.380(6), c= 22.667(9)Å, and Z= 4. The PPh₃ ligands are mutually trans about the Ru atom which, with the terpy ligand, lies on a mirror plane. The Ru–N distance trans to the hydride ligand is relatively long. The salicylate ion is internally hydrogen bonded. The complex displays a metal-to-ligand charge transfer transition (480 nm) and an irreversible metal oxidation Ru^II→Ru^III at ca. 0.6 V

High electrochemical performance flexible solid-state supercapacitor based on Co-doped reduced graphene oxide and silk fibroin composites.

A simple method for the preparation of flexible supercapacitor based on Co-doped reduced graphene oxide (rGO) and silk fibroin composites film is reported. The facile and cost-effective green pathways are chosen to reduce the exfoliated graphite oxide using a microbial strain, at room temperature. Doping process is performed by using in-situ precipitation technique. The Co-doped reduced graphene oxide (Co-rGO) is characterized by X-ray diffraction, Raman spectroscopy and Scanning Electron Microscopy (SEM). The as-prepared Co-rGO and silk fibroin are used to prepare flexible electrode for supercapacitor device. Electrochemical performance of the electrode is examined using cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The fabricated supercapacitor shows the specific capacitance of 104 F g−1 at a current density of 0.5 A g−1 in ionic liquid electrolyte (EMIm+BF4−). After a charge–discharge rate of 1 A g−1 for 10,000 cycles, the Co-rGO film exhibits remarkable electrochemical stability with the capacitance retention ratio of 89%. Furthermore, the Co-rGO film based supercapacitor achieves high energy density up to 28.31 Wh kg−1 at a power density of 78.24 kW kg−1 by using the ionic liquid electrolyte. The results shown in this work indicate that our proposed Co-rGO-silk fibroin composites film is a promising electrode material for manufacturing flexible supercapacitors

Bis(N,N) chelated rhenium(III) : the [ReL₂Cl₂]Cl family [L=2-(arylazo)pyridine]

The reaction of mer-[Re(MeCN)(PPh₃)₂Cl₃] with 2-(arylazo)pyridines (L) affords dark green, diamagnetic, 1 : 1 electrolytes [ReL₂Cl₂]Cl (aryl of L = Ph, m-MeC₆H₄ or p-ClC₆H₄). The ReCl₂ moiety is cis(two Re–Cl stretches) and the cation has an overall two-fold symmetry axis (¹H NMR spectra). The co-ordinated pyridine-nitrogen atoms and azo-nitrogen atoms of each ligand are assigned relative trans and cis geometries respectively. The N=N stretching frequencies are low (1280–1290 cm^–1) implying significant Re(t₂)–azo(π*) back bonding. In MeCN solution three nearly reversible redox couples occur with E½ values of ≈ 0.9 V [rhenium(IV)–rhenium(III)] and ≈–0.4, ≈–0.8 V (azo redox)vs. the saturated calomel electrode (SCE). A metal-to-ligand charge-transfer (m.l.c.t.) absorption is observed near 600 nm. The reduction potentials and m.l.c.t. frequencies are mutually consistent. The remarkable spectral and electrochemical similarities between [Re^IIIL₂Cl₂]Cl and [Os^IIL₂Cl₂] are noted and rationalised

Geometrical preference of ruthenium oxidation states: metal redox and isomerisation of [Ru(S₂CNEt₂)₂(PPh₃)₂]^0,+

Reaction of Na[S2CNEt2] with [Ru(PPh3)3Cl2] afforded cis-[RuL2(PPh3)2](L = S2CNEt2), which upon oxidation by cerium(IV) furnished trans-[RuL2(PPh3)2]+, isolated as its PF6– salt. Both complexes are obtained in nearly quantitative yields. The trivalent complex displays one-electron paramagnetism and a rhombic frozen-solution EPR spectrum which has been analysed affording axial and rhombic distortion parameters of ≈ 8000 and ≈ 1700 cm–1 respectively. A ligand-field transition within the Kramers doublets is observed at 6450 cm–1, the predicted value being ≈ 7000 cm–1. Variable-temperature (253–303 K) voltammetric studies have revealed that electrode reactions proceed in a stereoretentive fashion [E½(cis), 0.23 and E½(trans), –0.09 V vs. saturated calomel electrode (SCE)] but the species cis-[RuL2(PPh3)2]+ and trans-[RuL2(PPh3)2] are unstable and spontaneously isomerise affording the stable trans-trivalent and cis-bivalent complexes respectively, the equilibrium concentration of the unstable isomers being very small. The rates and activation parameters of these isomerisation reactions presumably proceeding by the twist mechanism (ΔS‡ highly negative) have been determined. The factors controlling geometrical preference of oxidation states viz., metal–phosphorus back-bonding and PPh3···PPh3 steric repulsion are considered in relation to the osmium analogues reported previously

Facile aldimine .fwdarw. amide oxidation in a rhenium complex

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Geometrical isomer preference of Ru<SUP>II</SUP> and Ru<SUP>III</SUP>: chemistry and structure of a RuS<SUB>4</SUB>P<SUB>2</SUB> family. Crystal structure of [Ru(PhCH<SUB>2</SUB>SCS<SUB>2</SUB>)<SUB>2</SUB>(PPh<SUB>3</SUB>)<SUB>2</SUB>]

The syntheses of mixed thioxanthate (trithiocarbonate)-phosphine complexes of types cis-[Ru(RSCS2 )2(PPh3)2](1) and trans-[Ru(RSCS2)2 (PPh3)2]PF6(2+) are reported (R = Et, Pri, or PhCH2). These along with trans-[Ru(RSCS2)2(PPh3) 2](2) and cis-[Ru(RSCS2)2(PPh3)2] +(1+) constitute an electrochemically observable redox isomerisation cycle. The formal potentials of the couples (1+)-(1) and (2+)-(2) are ≈ 0.65 and ≈ 0.33 V respectively vs. saturated calomel electrode (s.c.e.). The isomerisation steps are (1+)→(2+)(fast) and (2)→(1)(k≈ 7.0 x 10-2 s-1). The X-ray structure of complex (1; R = PhCH2) has been determined: space group C2/c, a= 18.676(7), b= 10.511(2), c= 24.432(8)Å , and Z = 4. The superior stability of the cis configuration of RuII for complexes (1) arises primarily from the strong back-bonding (cis &gt; trans) within the Ru(PPh3)2 fragment. For RuIII, in which back-bonding is unimportant, the stable geometry is trans owing to favourable steric disposition of the PPh3 molecules. The frozen glass e.s.r. spectra of complexes (2+) have a sizable axial distortion (Δ≈ 8 500 cm-1) with a relatively small rhombic component (V≈ 2 200 cm-1). One of the two predicted transitions (∨ 1≈ 7 500 and ∨2≈ 9 900 cm-1) within the t2g shell is observable (∨1≈ 6 500 cm-1) in the near-i.r. region

Valence specific chelation of ruthenium to Schiff mono-bases of 2,6-diformyl-4methylphenol : synthesis and structure of trivalent salicylaldiminato species of coordination type RuN<SUB>2</SUB>O<SUB>2</SUB>PCl

The reaction of Schiff mono-bases, HRL (R = Me, Et), of 2,6-diformyl-4-methylphenol with K2 RuCl,(H2O) has afforded RuIII(RL)2(PPh3)Cl. The X-ray structure of the R = Et complex has revealed metal chelation at the salicylaldimine segment of RL-, the two phenolic oxygen and azomethine nitrogen atoms lying in mutually trans and cis positions, respectively. The trivalent state of the metal is stabilized in Ru(RL)2(P-Ph3)Cl, the ruthenium (III)/ruthenium(II) E1/2 being ~0.40 V vs SCE. These distorted low-spin (t25) complexes display rhombic EPR spectra and are characterized by a pair of ligand field transitions (in the near-IR region) within the split t2 shell. The complexes provide a striking contrast with the ruthenium(II) organometallics arising from the reaction of HRL with RuII(PPh3)3Cl2