Promises of anionic calix[n]arenes in life science: State of the art in 2023.

Because they hold together molecules by means of non-covalent interactions - relatively weak and thus, potentially reversible - the anionic calixarenes have become an interesting tool for efficiently binding a large range of ligands - from gases to large organic molecules. Being highly water soluble and conveniently biocompatible, they showed growing interest for many interdisciplinary fields, particularly in biology and medicine. Thanks to their intrinsic conical shape, they provide suitable platforms, from vesicles to bilayers.

para-Sulphonato-calix[n]arene capped silver nanoparticles challenge the catalytic efficiency and the stability of a novel human gut serine protease inhibitor.

The Eubacterium saburreum serine protease inhibitor from the human gut microbiota inhibits the eukaryotic pancreatic elastase associated with acute pancreatitis. Interestingly, the inhibition efficiency and stability are markedly increased by the para-sulphonato-calix[8]arene capped silver nanoparticles. Moreover, this enzyme is distinguishable by its high inhibitory effect at broad pH range between 2-10 and temperatures from 10 to 40 °C, in the presence of para-sulphonato-calix[8]arene capped silver nanoparticles the enzyme remains active even at 70 °C.

Fused Deposition Modeling 3D Printing: Test Platforms for Evaluating Post-Fabrication Chemical Modifications and In-Vitro Biological Properties.

3D printing is attracting considerable interest for its capacity to produce prototypes and small production runs rapidly. Fused deposit modeling (FDM) was used to produce polyvalent test plates for investigation of the physical, chemical, and in-vitro biological properties of printed materials. The polyvalent test plates (PVTPs) are poly-lactic acid cylinders, 14 mm in diameter and 3 mm in height.

Size and Flexibility Define the Inhibition of the H3N2 Influenza Endonuclease Enzyme by Calix[n]arenes.

Inhibition of H3N2 influenza PA endonuclease activity by a panel of anionic calix[n]arenes and β-cyclodextrin sulfate has been studied. The joint experimental and theoretical results reveal that the larger, more flexible and highly water-soluble sulfonato-calix[n]arenes have high inhibitory activity, with para-sulfonato-calix[8]arene, SC8, having an IC value of 6.4 μM.

Direct measurement of the mechanical properties of a chromatin analog and the epigenetic effects of para-sulphonato-calix[4]arene.

By means of Silicon Nano Tweezers (SNTs) the effects on the mechanical properties of λ-phage DNA during interaction with calf thymus nucleosome to form an artificial chromatin analog were measured. At a concentration of 100 nM, a nucleosome solution induced a strong stiffening effect on DNA (1.1 N m).

Elucidating the mechanism of the considerable mechanical stiffening of DNA induced by the couple Zn/Calix[4]arene-1,3-O-diphosphorous acid.

The couple Calix[4]arene-1,3-O-diphosphorous acid (C4diP) and zinc ions (Zn) acts as a synergistic DNA binder. Silicon NanoTweezer (SNT) measurements show an increase in the mechanical stiffness of DNA bundles by a factor of >150, at Zn to C4diP ratios above 8, as compared to Zinc alone whereas C4diP alone decreases the stiffness of DNA. Electroanalytical measurements using 3D printed devices demonstrate a progression of events in the assembly of C4diP on DNA promoted by zinc ions.

A rapid and practical technique for real-time monitoring of biomolecular interactions using mechanical responses of macromolecules.

Monitoring biological reactions using the mechanical response of macromolecules is an alternative approach to immunoassays for providing real-time information about the underlying molecular mechanisms. Although force spectroscopy techniques, e.g.

Bio-Applications of Calix[n]arene Capped Silver Nanoparticles.

During the 10 last years, there has been a growing interest in calix[n]arene capped silver nanoparticles for their uses in biosensing and much more recently for their intrinsic therapeutic properties. Cost effective, portable and ultra-sensitive analytical tools are one of the major expectations of silver nanoparticles capped with calix[n]arenes. Their uses for detecting a wide range of hazardous molecules and biological compounds by different physical approaches (optical or electrical) are reviewed in depth here.

para-Sulphonato-calix[n]arenes as selective activators for the passage of molecules across the Caco-2 model intestinal membrane.

The passage of Lucifer Yellow across the Caco-2 intestinal model membrane has been studied for the para-sulphonato-calix[n]arenes, the results show that para-sulphonato-calix[4]arene and para-sulphonato-calix[8]arene activate membrane passage when used simultaneously with a transport probe, Lucifer Yellow, whereas para-sulphonato-calix[6]arene has no effect.

Large negatively charged organic host molecules as inhibitors of endonuclease enzymes.

Three large negatively charged organic host molecules; β-cyclodextrin sulphate, para-sulphonato-calix[6]arene and para-sulphonato-calix[8]arene have been shown to be effective inhibitors of endonuclease in the low micromolar range, additionally para-sulphonato-calix[8]arene is a partial inhibitor of rhDNase I.

Solid lipid nanoparticle-based calix[n]arenes and calix-resorcinarenes as building blocks: synthesis, formulation and characterization.

Solid lipid nanoparticles (SLNs) have attracted increasing attention during recent years. This paper presents an overview about the use of calix[n]arenes and calix-resorcinarenes in the formulation of SLNs. Because of their specific inclusion capability both in the intraparticle spaces and in the host cavities as well as their capacity for functionalization, these colloidal nanostructures represent excellent tools for the encapsulation of different active pharmaceutical ingredients (APIs) in the area of drug targeting, cosmetic additives, contrast agents, etc.

Molecular recognition by gold, silver and copper nanoparticles.

The intrinsic physical properties of the noble metal nanoparticles, which are highly sensitive to the nature of their local molecular environment, make such systems ideal for the detection of molecular recognition events. The current review describes the state of the art concerning molecular recognition of Noble metal nanoparticles. In the first part the preparation of such nanoparticles is discussed along with methods of capping and stabilization.

Discriminatory antibacterial effects of calix[n]arene capped silver nanoparticles with regard to gram positive and gram negative bacteria.

Silver nanoparticles capped with nine different sulphonated calix[n]arenes were tested for their anti-bacterial effects against B. subtilis and E. coli at an apparent concentration of 100 nM in calix[n]arene.

Anionic calixarene-capped silver nanoparticles show species-dependent binding to serum albumins.

The anionic calixarenes para-sulphonatocalix[4]arene and 1,3-di-O-phosphonatocalix[ 4]arene, have been used to cap silver nanoparticles. The binding of these functional particles with regard to various serum albumins (bovine serum albumin, human serum albumin, porcine serum albumin and sheep serum albumin) has been studied by variable temperature fluorescence spectroscopy. The quenching of the fluorescence of the proteins was shown to vary as a function of the anionic calixarene capping molecule and also as a function of the origin of the serum albumin.

Calix-arene silver nanoparticles interactions with surfactants are charge, size and critical micellar concentration dependent.

The interactions of silver nanoparticles capped by various calix[n]arenes bearing sulphonate groups at the para and/or phenolic faces with cationic, neutral and anionic surfactants have been studied. Changes in the plasmonic absorption show that only the calix[4]arene derivatives sulphonated at the para-position interact and then only with cationic surfactants. The interactions follow the CMC values of the surfactants either as simple molecules or mixed micelles.

Transformations of griseofulvin in strong acidic conditions--crystal structures of 2'-demethylgriseofulvin and dimerized griseofulvin.

The structure of griseofulvic acid, C16H15ClO6, at 100 K has orthorhombic (P2(1)2(1)2) symmetry. It is of interest with respect to biological activity. The structure displays intermolecular O-H.

Surface acoustic wave sensing of linear alcohols using para-acylcalix[n]arenes.

para-Hexanoylcalix[4, 6 or 8]arenes have been used as surface acoustic wave sensor capture layers showing a high efficiency for the detection of linear alcohols, with high reproducibility and rapid response times.

Supramolecular stabilization of acid tolerant L-arabinose isomerase from Lactobacillus sakei.

L-Arabinose isomerase stability is a crucial criterion for the industrial application of this biocatalyst. Noria and NoriaPG are capable of increasing the L-arabinose isomerase stability not only at high temperatures but also at low pH. Such results highlight, for the first time, the use of the Noria series of molecules for protein stabilization and activation.

The structure of water in p-sulfonatocalix[4]arene.

Tetrasodium p-sulfonatocalix[4]arene exists as a hydrate with approximately 14 water molecules and has three polymorphic modifications, all of which contain a water molecule in the molecular cavity that is engaged in OH···π interactions. Single-crystal neutron structures are reported for two of these three forms and reveal a "compressed" water molecule with short OH bonds. Partial atomic charges and hardness analysis (PACHA) calculations based on the neutron coordinates give an OH···π interaction energy of 6.

Colourimetric and spectroscopic discrimination between nucleotides and nucleosides using para-sulfonato-calix[4]arene capped silver nanoparticles.

The complexation of nucleosides and nucleotides by hybrid nanoparticles capped by para-sulfonato-calix[4]arene shows clear discrimination between purine and pyrimidine based molecules. For the pyrimidine nucleotides there is appearance of a new absorption band around 550 nm, and a colour change from yellow to orange red and pink.

A dodecameric self-assembled calix[4]arene aggregate with two types of cavities.

Twelve molecules of β-carbonyl-para-octyl-calix[4]arene assemble in an aggregate containing two types of cavities filled by water molecules and they pack in a cubic structure. Both the aggregates and the packing resemble that observed for inverse micelles.

Biochemistry of anionic calix[n]arenes.

This review treats the biological properties of the various anionic calix[n]arenes, both as soluble forms and in the colloidal state. The complexation of these molecules with amino-acids, peptides and proteins is discussed, as is their interaction with model membranes. The complexations with various Active Pharmaceutical Ingredients as complexes, for tamoxifen as solid state and colloidal structures, are treated in depth.

Structuring detergents for extracting and stabilizing functional membrane proteins.

Background: Membrane proteins are privileged pharmaceutical targets for which the development of structure-based drug design is challenging. One underlying reason is the fact that detergents do not stabilize membrane domains as efficiently as natural lipids in membranes, often leading to a partial to complete loss of activity/stability during protein extraction and purification and preventing crystallization in an active conformation.

Methodology/principal Findings: Anionic calix[4]arene based detergents (C4Cn, n=1-12) were designed to structure the membrane domains through hydrophobic interactions and a network of salt bridges with the basic residues found at the cytosol-membrane interface of membrane proteins.

Solid lipid nanoparticles (SLNs) derived from para-acyl-calix[9]-arene: preparation and stability.

A study of the parameters relating to the preparation of para-acyl-calix[9]arene-based solid lipid nanoparticles (SLNs) has been undertaken. Dynamic light scattering and electron microscopy have shown that the particle size varies between 85 and 215 nm depending on the acyl chain length. Parameters, including the organic solvent, amphiphile concentration and the presence of a co-surfactant affect the size of the SLNs obtained significantly.

Multifrequency EPR study of the mobility of nitroxides in solid-state calixarene nanocapsules.

Multifrequency continuous wave (cw) and echo-detected (ED) electron paramagnetic resonance (EPR) was employed to study the mobility of nitroxides confined in nanocapsules. The complexes p-hexanoyl calix[4]arene with 4-methoxy-2,2,6,6-tetramethylpiperidine-N-oxyl (MT) and N-(2-methylpropyl)-N-(1-diethylphosphono-2,2-dimethylpropyl)-aminoxyl (DEPN) were studied by X-, W-band and 360 GHz cw EPR at temperatures between 90 and 370 K. Thereby we were able to extract the canonical values of the hyperfine and g-tensors of the encapsulated radicals as well as information on restricted orientational dynamics of the caged spin probes.