Facile construction of polyoxometalate-polymer hybrid nanoparticles with pH/redox dual-responsiveness.

Responsive nanomaterials have emerged as promising candidates for advanced drug delivery systems (DDSs), offering the potential to precisely target disease sites and enhance treatment efficacy. To fulfil their potential, such materials need to be engineered to respond to specific variations in biological conditions. In this work, we present a series of pH/redox dual-responsive hybrid nanoparticles featuring an amphiphilic shell polymer and a pH-responsive core polymer.

Highly selective organo-gallium hydroxamate mediated inhibition of antibiotic resistant .

Five complexes of gallium derived from hydroxamic acids have been synthesised, characterised, and their anti-bacterial activity and mammalian cell toxicity established. These are three metal-organic complexes; [Ga(BPHA)] 1, [Ga(BHA-)] 2, [Ga(SHA-)(SHA-)] 3, and two heteroleptic organometallic complexes [GaMe(BPHA)] 4, and [GaMe(BHA-)] 5, along with the iron complex [Fe(BPHA)] 6 (BPHA-H = -benzoyl--phenylhydroxamic acid, BHA-H = phenylhydroxamic acid, and SHA-H = salicylhydroxamic acid). Solid-state structures of 1, 4-6 were identified by single-crystal X-ray crystallography.

Tri-aryl antimony(V) hydroximato and hydroxamato complexes: Combining lipophilic Sb(III/V) and hydroxamic acids in combating Leishmania.

Six novel tri-aryl antimony(V) hydroximato complexes (3-8) with composition [SbAr(ONCR)] (3: Ar = Ph, R = o-(OH)Ph, 4: Ar = Ph, R = Me, 5: Ar = Ph, R = Ph; 6: Ar = Mes, R = Me, 7: Ar = Mes, R = Ph, 8: Ar = Mes, R = o-(OH)Ph (where Ph = phenyl, Me = methyl, Mes = mesityl)), were synthesised and evaluated for anti-parasitic activity towards Leishmania major (L. major) promastigotes and amastigotes. Complexes of the form [SbAr(ONCR)], with the dianionic hydroximato ligand binding O,O'-bidentate to the Sb(V) centre, exist in the solid-state for the mesityl-derived complexes.

Structure-activity effects in the anti-leishmanial activity of di-alkyl gallium quinolin-8-olates.

Six (G1-G6) novel organogallium complexes of the general formula [Ga(R)quin] (where R = Et, Pr, Bu, Bu, Bu and hexyl; quin = quinolin-8-olate, CHNO) have been synthesised and fully characterised. Single crystal X-ray diffraction shows the complexes adopt a five-coordinate geometry through dimerisation. Complexes G1-G5 were analytically pure and could undergo further biological analysis.

Enhanced antibacterial activity of dimethyl gallium quinolinolates toward drug-resistant Klebsiella pneumoniae in low iron environments.

A series of dimethylgallium quinolinolate [GaMeL] (L = 5-chloroquinolinolate, 5, 7-dichloroquinolinolate, 5, 7-dibromoquinolinolate or 5, 7-doiodoquinolinolate) complexes, shown previously to be active toward the Leishmania parasite, have been studied for their antibacterial activity toward a reference and drug resistant strain of Klebsiella pneumoniae (KP). The assays were conducted in standard iron-rich LB media and in the iron depleted RPMI and RPMI-HS media to better understand the effect of Fe concentration on the activity of the Ga complexes. In LB broth the parent quinolinols and the gallium complexes were inactive up to the highest concentration tested, 100 μM.

Gallium reactivates first and second generation quinolone antibiotics towards drug-resistant .

Herein, we report on a series of homoleptic [GaL] and heteroleptic organometallic [GaMeL] complexes of inactive quinolone antibiotics; nalidixic acid, oxolinic acid and norfloxacin with their antibacterial activity (MIC 0.024-0.781 μM) towards four multi-drug resistant strains of through complexation to gallium.

Synchrotron-Infrared Microspectroscopy of Live Infected Macrophages and Isolated Promastigotes and Amastigotes.

The prevalence of neglected tropical diseases (NTDs) is advancing at an alarming rate. The NTD leishmaniasis is now endemic in over 90 tropical and sub-tropical low socioeconomic countries. Current diagnosis for this disease involves serological assessment of infected tissue by either light microscopy, antibody tests, or culturing with in vitro or in vivo animal inoculation.

Modulating aryl substitution: Does it play a role in the anti-leishmanial activity of a series of tetra-aryl Sb(V) fluorinated carboxylates?

Eight tetra-arylantimony carboxylates of the general formula ArSbOC(O)R with Ar = Ph (a), p-Tol (b), R = CF (1), CHCF (2), CFBr (3), CFCFCF (4) have been synthesised and characterised. Two of them (2b, 3b) are structurally novel. All structures were analytically characterised by FT-IR, H, C NMR spectroscopy.

The thiol-based reduction of Bi(V) and Sb(V) anti-leishmanial complexes.

Low molecular weight thiols including trypanothione and glutathione play an important function in the cellular growth, maintenance and reduction of oxidative stress in Leishmania species. In particular, parasite specific trypanothione has been established as a prime target for new anti-leishmania drugs. Previous studies into the interaction of the front-line Sb(V) based anti-leishmanial drug meglumine antimoniate with glutathione, have demonstrated that a reduction pathway may be responsible for its effective and selective nature.

Development of new combination anti-leishmanial complexes: Triphenyl Sb(V) mono-hydroxy mono-quinolinolates.

In seeking to develop single entity combination anti-Leishmanial complexes six heteropletic organometallic Sb(V) hydroxido quinolinolate complexes of general formula [SbPh(CHNORR')(OH)] have been synthesised and characterised, derived from a series of halide substituted quinolinols (8-hydroxyquinolines). Single crystal X-ray diffraction on all the complexes show a common distorted six-coordinate octahedral environment at the Sb(V) centre, with the aryl groups and nitrogen atom of quinolinolate ligand bonding in the equatorial planes, with the two oxygen atoms (hydroxyl and quinolinolate) occupying the axial plane in an almost linear configuration. Each complex was tested for their anti-promastigote activity and mammalian cytotoxicity and a selectivity indices established.

Impact of structural changes in heteroleptic bismuth phosphinates on their antibacterial activity in Bi-nanocellulose composites.

To study and evaluate the effect of ligand choice and distribution in bismuth phosphinates on toxicity and antibacterial activity, a series of novel diphenyl mono-phosphinato bismuth complexes, [BiPh2(O(O[double bond, length as m-dash])P(H)Ph)] 1, [BiPh2(O(O[double bond, length as m-dash])PPh2)] 2, [BiPh2(O(O[double bond, length as m-dash])PMe2)] 3 and [BiPh2(O(O[double bond, length as m-dash])P(p-MeOPh)2)] 4, were synthesised, characterised and structurally authenticated by X-ray crystallography. Evaluation of their antibacterial activity towards Staphylococcus aureus (S. aureus), methicillin-resistant S.

Is Bismuth Really the "Green" Metal? Exploring the Antimicrobial Activity and Cytotoxicity of Organobismuth Thiolate Complexes.

Antimicrobial resistance is becoming an ever-increasing threat for human health. Metal complexes and, in particular, those that incorporate bismuth offer an attractive alternative to the typically used organic compounds to which bacteria are often able to develop resistance determinants. Herein we report the synthesis, characterization, and biological evaluation of a series of homo- and heteroleptic bismuth(III) thiolates incorporating either one (BiPhL), two (BiPhL), or three (BiL) sulfur-containing azole ligands where LH = tetrazolethiols or triazolethiols (thiones).

Anti-leishmanial activity and cytotoxicity of a series of tris-aryl Sb(V) mandelate cyclometallate complexes.

A series of ten cyclometallates and two μ-peroxo bridged tris-aryl Sb(V) complexes derived from R/S-mandelic acid (= R/S-ManH) were synthesised and characterised. As confirmed by X-ray crystallography the complexes 1Sr/s, [Sb(o-tol)(man)], 2Sr/s, [Sb(m-tol)(man)], 4Sr/s, [Sb(o-PhOMe)(man)], 5Sr/s, [Sb(Mes)(man)] and 6Sr/s, [Sb(p-tert-BuPh)(man)] are all cyclometallates. Complexes 3Sr/s, [(Sb(p-tol)(manH)O], contain a bridging O anion in the solid-state but convert to the cyclometallates in DMSO solution with concomitant release of HO and formation of complexes [Sb(p-tol)(man)], 3Sr'/s'.

Alkyl gallium(III) quinolinolates: A new class of highly selective anti-leishmanial agents.

A series of eight alkyl gallium complexes of general formulae [GaMe(L)] and [Ga(Me)L] have been synthesised, characterised and their antimicrobial activity against bacteria, cancer cells and Leishmania assessed. All eight complexes are novel, with the solid-state structures of all complexes successfully authenticated by single crystal X-ray diffraction. The dimethyl complexes all adopt a four-coordinate tetrahedral confirmation, while the monomethyl complexes are five-coordinate trigonal bipyramidal.

Comparative stability, cytotoxicity and anti-leishmanial activity of analogous organometallic Sb(V) and Bi(V) acetato complexes: Sb confirms potential while Bi fails the test.

A series of sixteen triphenyl Bi(V) and Sb(V) acetato complexes of general formula [MPh(OCCR)] and one oxido-bridge antimony complex [(SbPh(OCOC(O)Me))O], have been synthesised and characterised, thirteen of which are novel. The solid-state structures of fifteen of the complexes have been successfully authenticated by single crystal X-ray diffraction. All structures, excluding the oxido-bridge antimony complex, adopt a typical trigonal bipyramidal confirmation with the phenyl rings in a propeller-like orientation in the equatorial plane.

Comparative stability, toxicity and anti-leishmanial activity of triphenyl antimony(v) and bismuth(v) α-hydroxy carboxylato complexes.

A series of triphenyl Sb(v) and Bi(v) α-hydroxy carboxylato complexes of the general formula [MPh(OCROH)] and [MPh(OCRO)] have been successfully synthesised and characterised, and subsequently assayed for their comparative activity towards Leishmania parasites and human fibroblast cells. Four complexes are novel; [SbPhGly], [BiPh(GlyH)], [SbPh(R-ManH)] and [SbPh(S-ManH)], and have been structurally characterised through X-ray diffraction. These were combined in the study with the known complexes; ([SbPh(R-Man)], [SbPh(S-Man)], [BiPh(R-ManH)], [BiPh(R-ManH)], [SbPh(BenzH)], [BiPh(BenzH)], for which the crystal structures of [BiPh(S-ManH)] and [BiPh(R-Man)] have now been authenticated (GlyH = glycolic acid, R/S-ManH = mandelic acid, BenzH = benzilic acid).