Efficient immobilization of firefly luciferase in a metal organic framework: Fe-MIL-88(NH2) as a mighty support for this purpose.

We investigated the mechanism of luciferase immobilization on a solid surface through therphtalaldehyde in order to understand the role of this linker on stability and activity of luciferase. Metal organic frameworks (MOFs) are capable supports for the stabilization of some proteins and biomolecules, therefore, in this context for the first time, we report a light emmiting enzyme immobillization on one of these supports and then outline chemical developments in this process. To this end, Fe-MIL-88(NH2) was used to immobilize native luciferase and therphtalaldehyde linker was attached to the framework as an activated group. Interestingly, high loading capacity was observed in both bonding mechanisms. Furthermore, thermal stability and kinetic properties were improved very much but, thermodynamic/kinetic results and bonding efficiency is much better in the modified-MOF than native MOF. It was found that Schiff base mechanism between aldehyde as an active functional group in MOF and amine groups of enzyme led to the formation of imine bond. The surface chemical structure and morphologies of Fe-MIL-88(NH2) were characterized by FTIR, X-ray diffraction, Brunauer-Emmett-Teller (BET), FE-SEM, and TEM. In conclusion, using Fe-MIL-88(NH2) as a support to immobilize luciferase established simple immobilization process of luciferase with and without linker and it improved the remaining activity significantly.

Antimicrobial photodynamic therapy assessment of three indocyanine green-loaded metal-organic frameworks against Enterococcus faecalis.

BACKGROUND: Antimicrobial photodynamic therapy (aPDT) has emerged as one of the promising non-invasive adjuvant treatments of endodontic infections. The key part of this technique is application of an optimized nontoxic photosensitizer (PS), like indocyanine green (ICG) which when activated by light can destroy bacterial contaminants. Notwithstanding all featured properties of ICG, this PS mainly suffers from the lack of stability and concentration-dependent aggregation. A variety of nanomaterials (NMs) has been widely exploited to improve the stability and efficiency of ICG. The objective of this study was to evaluate and compare the efficiency of three high capacious metal organic frameworks (MOFs) to produce MOF-ICG as novel PSs improving ICG loading, stability and antimicrobial activity. This is first report on ICG-loaded MOFs for aPDT against endodontic infections. MATERIALS AND METHODS: Three different nano-MOFs were synthesized (denoted as Fe-101, Al-101 and Fe-88), and employed for ICG loading (MOF-ICG). The stability of immobilized ICG, antimicrobial and anti-biofilm properties of MOF-ICG against Enterococcus faecalis (E. faecalis) as one of the main factors of endodontic infections as well as expression ratio of the esp gene in E. faecalis were evaluated. RESULTS: Fe-101 and Al-101 showed acceptable ICG loading (ICG loading capacity of 16.93 ± 0.32 and 18.17 ± 0.31, respectively) as well as considerable enhanced aqueous stability (percent of degradation were only 14% and 17%, respectively) in comparison to free ICG (percent of degradation was 95%) after 10 days. ICG-free MOFs could surprisingly suppress the viability of E. faecalis after laser irradiation up to 18.1%, 28.8%, and 38.3% for Al-101, Fe-88 and Fe-101, respectively. ICG loaded MOFs mediated aPDT could significantly reduce the count of E. faecalis to 60.72%, 45.12%, and 62.67%, respectively (p < 0.05). The Fe-88-ICG-PDT, Fe-101-ICG-PDT and Al-101-ICG-PDT considerably dropped the biofilm formation of E. faecalis by 37.54%, 47.01% and 53.68% (p < 0.05). The expression of esp gene was also remarkably declined to 4.4-, 6.0- and 6.2-fold after aPDT in the presence of Fe-88-ICG, Al-101-ICG and Fe-101-ICG, respectively (P < 0.05). CONCLUSION: Owing to the significant features of the Fe-101 including acceptable ICG loading and stability, as well as reasonable antimicrobial effect after ICG loading in comparison to free ICG, it could be considered as a promising nano-PSs in aPDT to remove E. faecalis.

Application of surface modified nano ferrite nickel in catalytic reaction (epoxidation of alkenes) and investigation on its antibacterial and antifungal activities.

Newly, magnetic nanoparticles have extensively been used as alternative catalyst supports, in the view of their high surface area which results in high catalyst loading capacity, high dispersion, low toxicity, environmental preservation, distinguished stability, and suitable catalyst reusing. In the present study, the magnetite nanoparticles, NiFe2O4@Ag and NiFe2O4@Mo, were synthesized and characterized. The antimicrobial activities and catalytic properties of synthesized nanoparticles were tested afterwards. For synthetizing the nanoparticle NiFe2O4@Ag, silver ions were loaded onto the surface of the modified NiFe2O4 and reduced to silver crystal by adding NaBH4. The antibacterial effects of NiFe2O4@Ag were examined against two species of soil and plant related bacteria named Bacillus subtilis (gram positive) and Pseudomonas syringae (gram negative), respectively. The antifungal activity of this nanoparticle was evaluated against two species of plant pathogenic fungi called Alternaria solani and Fusarium oxysporum. Biological results indicated that the synthesized material has shown an excellent antibacterial and antifungal activity against all examined bacteria and fungi so that, their growth were completely inhibited 24h after treatment with NiFe2O4@Ag. For the synthesis of a heterogeneous catalyst NiFe2O4@Mo, complex Mo(CO)6 was loaded onto the surface of the modified NiFe2O4 nanoparticle. This catalyst was found as an efficient catalyst for epoxidation of cis-cyclooctene and a wide variety of alkenes, including aromatic and aliphatic terminal ones using tert-butyl hydroperoxide as oxidant. This new heterogenized catalyst could easily be recovered by using a magnetic separator and reused four consecutive and loss only 13% of its catalytic activity.

[4-Bromo-N-(pyridin-2-yl-methyl-idene)aniline-κ(2)N,N']iodido(triphenyl-phosphane-κP)copper(I).

In the title compound, [CuI(C(12)H(9)BrN(2))(C(18)H(15)P)], the Cu(I) ion is bonded to one I atom, one triphenyl-phosphane P atom and two N atoms of the diimine ligand in a distorted tetra-hedral geometry. The Schiff base acts as a chelating ligand and coordinates to the Cu(I) atom via two N atoms. In the diimine ligand, the dihedral angle between the pyridine and bromo-phenyl rings is 19.2 (2)°. In the crystal, mol-ecules are connected by π-π stacking inter-actions between inversion-related pyridine rings [centroid-centroid distance = 3.404 (3) Å].

Synthesis and application of chloromethylated polystyrene modified with 1-phenyl-1,2-propanedione-2-oxime thiosemicarbazone (PPDOT) as a new sorbent for the on-line preconcentration and determination of copper in water, soil, and food samples by FAAS.

In this paper, we report a simple and sensitive on-line solid phase extraction system for the preconcentration and determination of Cu(II) by flame atomic absorption spectrometry (FAAS). This method is based upon the on-line retention of copper at pH 5.0 on a minicolumn packed with chloromethylated polystyrene modified by 1-phenyl-1,2-propanedione-2-oxime thiosemicarbazone (PPDOT) as a new solid-phase extraction (SPE) sorbent. The retained Cu(II) ions were eluted with 1.0M HNO(3), and transported directly to FAAS for determination. Several chemical and flow variables were studied and optimized for a quantitative preconcentration and determination of copper(II). At the optimized conditions, for preconcentration of 10.0 mL of a sample solution, a linear calibration graph was obtained over the concentration range of 3.00-120.0 µg L(-1) for Cu(II). The limit of detection (3σ), limit of quantification (10σ), and enrichment factor are 0.56 µg L(-1), 2.0 µg L(-1) and 41, respectively. The relative standard deviation (n = 6) at 20 µg L(-1) of Cu(II) is 2.0%. This method could be applied for determination of trace amounts of Cu(II) in water, soil, and food samples with satisfactory results.