The biological Maxwell's demons: exploring ideas about the information processing in biological systems

This work is based on ideas supported by some of the biologists who discovered foundational facts of twentieth-century biology and who argued that Maxwell's demons are physically implemented by biological devices. In particular, JBS Haldane first, and later J. Monod, A, Lwoff and F. Jacob argued that enzymes and molecular receptors implemented Maxwell's demons that operate in systems far removed from thermodynamic equilibrium and that were responsible for creating the biological order. Later, these ideas were extended to other biological processes. In this article, we argue that these biological Maxwell's demons (BMD) are systems that have information processing capabilities that allow them to select their inputs and direct their outputs toward targets. In this context, we propose the idea that these BMD are information catalysts in which the processed information has broad thermodynamic consequences.

Metal–Peptide Complexes—A Novel Class of Molecular Receptors for Electrochemical Phosphate Sensing

Amyloid-β (Aβ) peptides are crucial in the pathology of Alzheimer’s disease. On the other hand, their metal complexes possess distinctive coordination properties that could be of great importance in the selective recognition of (bio)analytes, such as anions. Here, we report a novel group of molecular receptors for phosphate anions recognition: metal–peptide complexes of Aβ peptides, which combine features of synthetic inorganic ligands and naturally occurring binding proteins. The influence of the change in the metal ion center on the coordination and redox properties of binary Cu(II)/Ni(II)-Aβ complexes, as well as the affinity of these complexes towards phosphate species, were analyzed. This approach offers the possibility of fine-tuning the receptor affinity for desired applications.

NEW MOLECULAR RECEPTORS FOR DIAGNOSIS AND THERAPY OF PANCREATIC DUCTAL ADENOCARCINOMA

INTRODUCTION Pancreatic ductal adenocarcinoma (PDAC) is one of the cancers with worst prognosis due to the intense desmoplastic reaction that occurs in this disease, which hinders the action of therapeutic agents and contributes to cancer progression. A possible way to develop new strategies for PDAC diagnosis and therapy is the study of the abnormal components of the tumor stroma. However, new receptors capable of detecting these components are needed. MATERIALS AND METHODS Two types of molecular receptors, monoclonal antibodies and aptamers, were developed in parallel targeting an extracellular matrix protein with potential as a PDAC marker. Antibodies were generated using mice of the DBA/1J strain, while aptamers were obtained by means of an in vitro selection method called SELEX. The analytical characteristics of the developed receptors were studied by ELISA-like assays, as well as cytochemistry on positive and negative cell lines for the protein of interest. RESULTS A total of 44 potential aptamers were identified. After a first bioinformatic screening, 9 candidates were chosen for evaluating their binding affinity in vitro. Two of them showed dissociation constants in the nanomolar range. One of the aptamers also showed specific staining of cells positive for the marker protein, as did one of the generated antibody clones. CONCLUSIONS The newly developed receptors have shown a great potential in the study of PDAC. However, their diagnostic and therapeutic usefulness requires a more in-depth evaluation, currently in progress. ACKNOWLEDGEMENTS This research was funded by the Spanish Government (RTI-2018-095756-B-I00) and Principado de Asturias Government (IDI2018-000217), co-financed by FEDER funds. R.L.G. thanks the Spanish Government for a predoctoral FPU fellowship (FPU16/05670).

Solution and Solid State Studies of Urea Derivatives of DITIPIRAM Acting as Powerful Anion Receptors

Herein, we present the synthesis and anion binding studies of a family of homologous molecular receptors 4–7 based on a DITIPIRAM (8-propyldithieno-[3,2-b:2′,3′-e]-pyridine-3,5-di-amine) platform decorated with various urea para-phenyl substituents (NO2, F, CF3, and Me). Solution, X-ray, and DFT studies reveal that the presented host–guest system offers a convergent array of four urea NH hydrogen bond donors to anions allowing the formation of remarkably stable complexes with carboxylates (acetate, benzoate) and chloride anions in solution, even in competitive solvent mixtures such as DMSO-d6/H2O 99.5/0.5 (v/v) and DMSO-d3/MeOH-d3 9:1 (v/v). The most effective derivatives among the series turned out to be receptors 5 and 6 containing electron-withdrawing F- and -CF3para-substituents, respectively.

Investigating the Potential of Flexible and Pre-Organized Tetraamide Ligands to Encapsulate Anions in One-Dimensional Coordination Polymers: Synthesis, Spectroscopic Studies and Crystal Structures

The synthesis of amide-based molecules, possessing pre-organized structures, has received significant attention due to their potential applications as molecular receptors and as components of nanomaterials. In this study, four extended tetraamide ligands incorporating ethylene and propylene spacers, namely 1,2-bis[N,N′-6-(3-pyridylmethylamido)pyridyl-2-carboxyamido]ethane (L1), 1,2-bis[N,N′-6-(4-pyridylmethylamido)pyridyl-2-carboxyamido]ethane (L2), 1,2-bis[N,N′-6-(3-pyridylmethylamido)pyridyl-2-carboxyamido]propane (L3) and 1,2-bis[N,N′-6-(4-pyridylmethylamido)pyridyl-2-carboxyamido]propane (L4), were successfully synthesized. Further, reaction of L2 and L4, incorporating pendant 4-pyridyl donors as the metal coordinating sites, with cadmium salts, produced two close-packed one-dimensional coordination polymers, {[Cd3(L2)4(H2O)10](NO3)6·12H2O·CH3OH}n and {[Cd(SO4)(L4)(H2O)2]·4H2O·CH3OH}n. X-ray crystallography reveals that the flexible tetraamide ligands fold upon themselves in the coordination polymer structure. As a consequence, the anion pocket in {[Cd(SO4)(L4)(H2O)2]·4H2O·CH3OH}n incorporating the ligand with the propylene spacer was blocked from encapsulating charge-balancing anions, which were involved in bridging the di-cadmium units. Interestingly, a strong interaction between the 2,6-pyridine dicarboxamide moiety with the nitrate anions was found in {[Cd3(L2)4(H2O)10](NO3)6·12H2O·CH3OH}n, showing potential for materials made from these ligands to serve as anion receptors.

Heteroditopic receptor flexibility – an important design principle for effective ion pair extractants based on carboxylates studies

Despite the continuous development of heteroditopic molecular receptors with the ability to transfer salts from the aqueous to the organic phase as symport, the factors contributing to the effectiveness of...

Supramolecular assembly of pyrene-tetrathiafulvalene hybrids on graphene: structure-property relationships and biosensing activity

Two different molecular receptors (1 and 2) incorporating one and three pyrene units to promote the π‒π interaction with the basal plane of graphene are reported. In order to modulate...

Copper(ii) complex of N-truncated amyloid-β peptide bearing a His-2 motif as a potential receptor for phosphate anions

Significant changes observed in the electrochemical response of the Cu(ii)-Aβ5–9 complex upon phosphates addition provided a new insight into the design of a promising class of peptide-based molecular receptors selective for phosphate species.