Synthetic organic dyes are widely used in various industrial sectors but are also among the most harmful water pollutants. In the last decade, significant efforts have been made to develop improved materials for the removal of dyes from water, in particular, on nanostructured adsorbent materials. Metal organic frameworks (MOFs) are an attractive class of hybrid nanostructured materials with an extremely wide range of applications including adsorption. In the present work, an iron-based Fe-BTC MOF, prepared according to a rapid, aqueous-based procedure, was used as an adsorbent for the removal of alizarin red S (ARS) and malachite green (MG) dyes from water. The synthesized material was characterized in detail, while the adsorption of the dyes was monitored by UV-Vis spectroscopy. An optimal adsorption pH of 4, likely due to the establishment of favorable interactions between dyes and Fe-BTC, was found. At this pH and at a temperature of 298 K, adsorption equilibrium was reached in less than 30 min following a pseudo-second order kinetics, with k″ of 4.29 × 10−3 and 3.98 × 10−2 g∙mg−1 min−1 for ARS and MG, respectively. The adsorption isotherm followed the Langmuir model with maximal adsorption capacities of 80 mg∙g−1 (ARS) and 177 mg∙g−1 (MG), and KL of 9.30·103 L∙mg−1 (ARS) and 51.56·103 L∙mg−1 (MG).
Nanomaterials are receiving high attention in the treatment and diagnosis [3] of neurological disorders where the classical pharmacological approach is not effective due to low blood brain barrier (BBB) permeability. An effective drug delivery method is combining of drugs with nanocarriers, for example, polymeric micelles, liposomes, lipid, and polymeric nanoparticles (NPs), that have high BBB affinities. [4] Metal ion chelators, which are bound covalently to nanoparticles, can facilitate drug entry into the brain. [5] Desferrioxamine (Desferal) is an iron (Fe), aluminum (Al), copper (Cu), and zinc (Zn) chelator that showed a decrease of AD progression in clinical trials, [2,6] even if the low BBB permeability of DFO is still debatable. [7] DFO conjugated to polystyrene NPs of 240 nm and examined in human cortical neurons in vitro prevented Aβ peptide aggregation, [8] the main component of the amyloid plaques found in the brains of people with Alzheimer's disease. [9] Nevertheless, low bioavailability and high toxicity restrict the use of metal chelators in humans. Functional nanoparticles are characterized by multiple incorporation of positron emitting radionuclides and signal enhancement in positron emission tomography (PET). [10] It has been Nanomaterials have received growing attention in the treatment and diagnosis of neurological disorders because the low blood brain barrier permeability hinders the classical pharmacological approach. Metal ion chelators combined with nanoparticles prove effective in the treatment of neurodegeneration and are under extensive studies. Most chelating agents and metallodrugs compete with endogenous molecules for metal coordination, and do not reach the active site. Determining the competition between metallodrugs and endogenous molecules requires knowing the stability constants of formed metal complexes. In this study, for the first time, potentiometric titrations are used to determine metal complex formation constants, and to quantify ligand content in functionalized materials. This new potentiometric approach allows physico-chemical characterization of mesoporous functionalized materials and their metal adsorption capacity in water solution. The potentiometric results are compared with isotherm models obtained by spectroscopic measurements and yield rewarding data fitting. The potentiometric method described here can be extended to different types of nanostructured materials carrying surface ionizable groups.
The purpose of this
work was the assembly of multicomponent nano-bioconjugates
based on mesoporous silica nanoparticles (MSNs), proteins (bovine
serum albumin, BSA, or lysozyme, LYZ), and gold nanoparticles (GNPs).
These nano-bioconjugates may find applications in nanomedicine as
theranostic devices. Indeed, MSNs can act as drug carriers, proteins
stabilize MSNs within the bloodstream, or may have therapeutic or
targeting functions. Finally, GNPs can either be used as contrast
agents for imaging or for photothermal therapy. Here, amino-functionalized
MSNs (MSN–NH
2
) were synthesized and characterized
through various techniques (small angle X-rays scattering TEM, N
2
adsorption/desorption isotherms, and thermogravimetric analysis
(TGA)). BSA or lysozyme were then grafted on the external surface
of MSN–NH
2
to obtain MSN–BSA and MSN–LYZ
bioconjugates, respectively. Protein immobilization on MSNs surface
was confirmed by Fourier transform infrared spectroscopy, ζ-potential
measurements, and TGA, which also allowed the estimation of protein
loading. The MSN–protein samples were then dispersed in a GNP
solution to obtain MSN–protein–GNPs nano-bioconjugates.
Transmission electron microscopy (TEM) analysis showed the occurrence
of GNPs on the MSN–protein surface, whereas almost no GNPs
occurred in the protein-free control samples. Fluorescence and Raman
spectroscopies suggested that proteins–GNP interactions involve
tryptophan residues.
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