Design of engineered cyclodextrin derivatives for spontaneous coating of highly porous metal-organic framework nanoparticles in aqueous media

Nanosized metal-organic frameworks (nanoMOFs) MIL-100(Fe) are highly porous and biodegradable materials that have emerged as promising drug nanocarriers. A challenging issue concerns their surface functionalization in order to evade the immune system and to provide molecular recognition ability, so that they can be used for specific targeting. A convenient method for their coating with tetraethylene glycol, polyethylene glycol, and mannose residues is reported herein. The method consists of the organic solvent-free self-assembly on the nanoMOFs of building blocks based on beta-cyclodextrin facially derivatized with the referred functional moieties, and multiple phosphate groups to anchor to the nanoparticles’ surface. The coating of nanoMOFs with cyclodextrin phosphate without further functional groups led to a significant decrease of macrophage uptake, slightly improved by polyethylene glycol or mannose-containing cyclodextrin phosphate coating. More notably, nanoMOFs modified with tetraethylene glycol-containing cyclodextrin phosphate displayed the most effcient “stealth” effect. Mannose-coated nanoMOFs displayed a remarkably enhanced binding affnity towards a specific mannose receptor, such as Concanavalin A, due to the multivalent display of the monosaccharide, as well as reduced macrophage internalization. Coating with tetraethylente glycol of nanoMOFs after loading with doxorubicin is also described. Therefore, phosphorylated cyclodextrins o er a versatile platform to coat nanoMOFs in an organic solvent-free, one step manner, providing them with new biorecognition and/or “stealth” properties

Design of Engineered Cyclodextrin Derivatives for Spontaneous Coating of Highly Porous Metal-Organic Framework Nanoparticles in Aqueous Media

Nanosized metal-organic frameworks (nanoMOFs) MIL-100(Fe) are highly porous and biodegradable materials that have emerged as promising drug nanocarriers. A challenging issue concerns their surface functionalization in order to evade the immune system and to provide molecular recognition ability, so that they can be used for specific targeting. A convenient method for their coating with tetraethylene glycol, polyethylene glycol, and mannose residues is reported herein. The method consists of the organic solvent-free self-assembly on the nanoMOFs of building blocks based on β-cyclodextrin facially derivatized with the referred functional moieties, and multiple phosphate groups to anchor to the nanoparticles’ surface. The coating of nanoMOFs with cyclodextrin phosphate without further functional groups led to a significant decrease of macrophage uptake, slightly improved by polyethylene glycol or mannose-containing cyclodextrin phosphate coating. More notably, nanoMOFs modified with tetraethylene glycol-containing cyclodextrin phosphate displayed the most efficient “stealth” effect. Mannose-coated nanoMOFs displayed a remarkably enhanced binding affinity towards a specific mannose receptor, such as Concanavalin A, due to the multivalent display of the monosaccharide, as well as reduced macrophage internalization. Coating with tetraethylente glycol of nanoMOFs after loading with doxorubicin is also described. Therefore, phosphorylated cyclodextrins offer a versatile platform to coat nanoMOFs in an organic solvent-free, one step manner, providing them with new biorecognition and/or “stealth” properties

One‐Step Photochemical Green Synthesis of Water‐Dispersible Ag, Au, and Au@Ag Core–Shell Nanoparticles

International audienc

Comb-like dextran copolymers: A versatile strategy to coat highly porous MOF nanoparticles with a PEG shell

International audienceNanoparticles made of metal-organic frameworks (nanoMOFs) are becoming of increasing interest as drug carriers. However, engineered coatings such as poly(ethylene glycol) (PEG) based ones are required to prevent nanoMOFs recognition and clearance by the innate immune system, a prerequisite for biomedical applications. This still presents an important challenge due to the highly porous structure and degradability of nanoMOFs. We provide here a proof of concept that the surface of iron-based nanoMOFs can be functionalized in a rapid, organic solvent-free and non-covalent manner using a novel family of comb-like copolymers made of dextran (DEX) grafted with both PEG and alendronate (ALN) moieties, which are iron complexing groups to anchor to the nanoMOFs surface. We describe the synthesis of DEX-ALN-PEG copolymers by click chemistry, with control of both the amount of PEG and ALN moieties. Stable DEX-ALN-PEG coatings substantially decreased their internalization by macrophages in vitro, providing new perspectives for biomedical applications

Molecular and Functional Characterization of Three Different Postzygotic Mutations in <i>PIK3CA</i>-Related Overgrowth Spectrum (PROS) Patients: Effects on PI3K/AKT/mTOR Signaling and Sensitivity to PIK3 Inhibitors

<div><p>Background</p><p><i>PIK3CA</i>-related overgrowth spectrum (PROS) include a group of disorders that affect only the terminal portion of a limb, such as type I macrodactyly, and conditions like fibroadipose overgrowth (FAO), megalencephaly-capillary malformation (MCAP) syndrome, congenital lipomatous asymmetric overgrowth of the trunk, lymphatic, capillary, venous, and combined-type vascular malformations, epidermal nevi, skeletal and spinal anomalies (CLOVES) syndrome and Hemihyperplasia Multiple Lipomatosis (HHML). Heterozygous postzygotic <i>PIK3CA</i> mutations are frequently identified in these syndromes, while timing and tissue specificity of the mutational event are likely responsible for the extreme phenotypic variability observed.</p><p>Methods</p><p>We carried out a combination of Sanger sequencing and targeted deep sequencing of genes involved in the PI3K/AKT/mTOR pathway in three patients (1 MCAP and 2 FAO) to identify causative mutations, and performed immunoblot analyses to assay the phosphorylation status of AKT and P70S6K in affected dermal fibroblasts. In addition, we evaluated their ability to grow in the absence of serum and their response to the PI3K inhibitors wortmannin and LY294002 <i>in vitro</i>.</p><p>Results and Conclusion</p><p>Our data indicate that patients’ cells showed constitutive activation of the PI3K/Akt pathway. Of note, PI3K pharmacological blockade resulted in a significant reduction of the proliferation rate in culture, suggesting that inhibition of PI3K might prove beneficial in future therapies for PROS patients.</p></div

Clinical and mutational spectrum of the three index cases.

<p><b>a</b> Patient 1, clinically diagnosed with MCAP, showing diffuse capillary malformation at the age of 2 months and cutaneous syndactyly between the 2^nd and 3^rd toes. The <i>PIK3CA</i> c.241 G>A [p.E81K] mutation detected by Sanger sequencing in affected cells and tissues of patient 1 showed varying levels of the mutant allele depending on the tissue tested. The mutation was absent in the patient's blood and in her parents. <b>b</b> Macrodactyly of the right 4^th finger in patient 2, diagnosed with FAO, at the age of 17 years. Sequence of <i>PIK3CA</i> exon 20 in blood and cultured fibroblasts obtained from patient 2 showing that the mutation is undetectable in these samples. <b>c</b> Patient 3, at the age of 15 months before surgical intervention; note the disproportion of the left 2^nd and 3^rd fingers and the subcutaneous mass at the left deltoid region. Sanger sequencing validation of the c.3140 A>T [p.H1047L] mutation detected with targeted deep sequencing in the biopsy from the 2^nd finger of patient 3. <b>d</b> List of samples and mutations detected with targeted deep sequencing. Coverage indicates the mean average of reads on target in the regions of interest (ROI) while frequency denotes the percentage of reads with the mutation.</p

Overactivation of the PI3K/Akt pathway is abrogated by pharmacological inhibition of PI3K in all patients tested.

<p><b>a</b> The indicated values are the result of the densitometric analysis of the phosphorylated forms of Akt and p70S6K normalized against total Akt and the loading control, respectively. The presented results are representative of at least three independent sets of experiments (bars represent standard deviation of the mean). <b>b</b> Immunoblot analysis of phospho-Akt (Ser473), phospho-Akt (Thr308), total Akt and phospho-p70S6K (Ser371) in mutant cells (fibroblasts from biopsies of FAO patient 2, and from left [L] and right [R] leg biopsies of MCAP patient 1) compared to IMR90 primary human normal fibroblasts (Ctrl). β-Actin was used as a loading control. Cells were treated with the PI3K inhibitor wortmannin (10μM) for 24 hours in the absence of growth factor stimulation. The presented results are representative of at least three independent sets of experiments. <b>c</b> Patients' affected cells are dependent on PI3K activity for proliferation. Primary fibroblasts obtained from biopsies were cultured in the presence or absence of wortmannin (10μM) and LY294002 (25μM). At the indicated time points, the proliferation index was determined using the WST-1 assay. The results were also confirmed by cell counting with trypan blue staining (data not shown). Each assay was performed in 6 replicates and the experiment was repeated six times. Statistical analysis was performed using Student’s t-tail test; *<i>P</i><0.05, which was considered statistically significant (bars represent standard deviation of the mean).</p