Metallopeptide nanoreservoirs for concurrent imaging and detoxification of lead (Pb) from human retinal pigment epithelial (hRPE1) cells

Inspired by natural metallopeptides, our work focuses on engineering self-assembling nanostructures of C2-symmetric metallopeptide conjugates (MPC) from a pyridine-bis-tripeptide bioprobe that uniquely detects lead (Pb2+) ions by emitting a fluorescence signal at 450 nm, which is further intensified in the presence of DAPI (λem = 458 nm), enhancing the bioimaging quality. This study enables precise lead quantification by modulating the ionic conformation and morphology. Experimental and theoretical insights elucidate the nanostructure formation mechanism, laying the groundwork for materials encapsulation and advancing lead detoxification. Our proof-of-principle experiment, demonstrating actin filament recovery in lead-treated cells, signifies therapeutic potential for intracellular lead aggregation and introduces novel avenues in biotechnological applications within biomaterials science.

Ratiometric fluorescent detection of lead ions in aquatic environment and living cells using a fluorescent peptide-based probe

Ratiometric fluorescent detection using dual emission bands is highly necessary to quantify Pb(II) in aquatic environment and live cells. We synthesized a ratiometric fluorescent peptidyl probe (1) by conjugation of a peptide receptor for Pb(II) with an excimer-forming benzothiazolylcyanovinylene fluorophore. The peptidyl probe dissolved well in aqueous solution and displayed an emission band at 538 nm (λ_ex = 460 nm). Upon addition of Pb(II) (0-20 μM), the emission maximum shifted from 538 nm to 575 nm and the emission intensity ratio (I₅₇₅ /I₅₃₈) increased significantly from 0.40 to 2.26. 1 exhibited a selective ratiometric response to Pb(II) over other metal ions. 1 with a low detection limit (1.2 ppb) of Pb(II) detected nanomolar concentrations (0-500 nM) of Pb(II) ions in groundwater and tap water. The cell-permeable probe detected intracellular Pb(II) by ratiometric fluorescent images. The binding mode study using NMR, IR and CD spectroscopy, and TEM revealed that the probe formed a 1:1 complex with Pb(II) and then formed red-emissive nanoparticles and fibrils. The probe exhibited desirable detection properties such as ratiometric detection, high solubility in water, visible light excitation, high selectivity and sensitivity for Pb(II), cell-permeability, and rapid response (< 6 min).

Two-step FRET mediated metal ion induced signalling responses in a probe appended with three fluorophores

A tri-fluorophore appended Tren receptor based probe exhibited chelation induced ratiometric fluorescence signalling through a two-step FRET process; enhancement of F_An→ F_Rhenergy transfer efficiency through an F_NBDintermediate was observed.

Signaling preferences of substituted pyrrole coupled six-membered rhodamine spirocyclic probes for Hg2+ ion detection

Six-membered spiro-ring expanded probes in rhodamine scaffolds exhibit Hg²⁺ ion specific dual mode signaling responses; specificity is achieved with tuning substituents on the appended pyrrole receptor.

Me3N-promoted synthesis of 2,3,4,4a-tetrahydroxanthen-1-one: preparation of thiosemicarbazone derivatives, their solid state self-assembly and antimicrobial properties

Thiosemicarbazones (5a–5j) have been synthesized from 2,3,4,4a-tetrahydroxanthen-1-one, obtained in high yield through Me₃N-promoted domino Baylis–Hillman/oxa-Michael reaction. Their solid-state self-assembly and antimicrobial properties are studied.

Dual mode signaling responses of a rhodamine based probe and its immobilization onto a silica gel surface for specific mercury ion detection

The amino-ethyl-rhodamine-B based probe 2 appended with a 3-aminomethyl-(2-amino-1-pyridyl) group retained its Hg(ii)-specific chromogenic and fluorogenic signaling responses in an aqueous medium even upon immobilization onto a silica gel surface for selective detection and extraction of Hg(ii) ions.