Supramolecular transcription of guanosine monophosphate into mesostructured silica

Machine-Learning-Driven G-Quartet-Based Circularly Polarized Luminescence Materials

Circularly polarized luminescence (CPL) materials have garnered significant interest due to their potential applications in chiral functional devices. Synthesizing CPL materials with a high dissymmetry factor (glum ) remains a significant challenge. Inspired by efficient machine learning (ML) applications in scientific research, this work demonstrates ML-based techniques for the first time to guide the synthesis of G-quartet-based CPL gels with high glum values and multiple chiral regulation strategies. Employing an "experiment-prediction-verification" approach, this work devises a ML classification and regression model for the solvothermal synthesis of G-quartet gels in deep eutectic solvents. This process illustrates the relationship between various synthesis parameters and the glum value. The decision tree algorithm demonstrates superior performance across six ML models, with model accuracy and determination coefficients amounting to 0.97 and 0.96, respectively. The screened CPL gels exhibiting a glum value up to 0.15 are obtained through combined ML guidance and experimental verification, among the highest ones reported till now for biomolecule-based CPL systems. These findings indicate that ML can streamline the rational design of chiral nanomaterials, thereby expediting their further development.

Equilibrium and Kinetic Study of l- and d-Valine Adsorption in Supramolecular-Templated Chiral Mesoporous Materials

Adsorption kinetic studies are conducted to investigate the potential to use chiral mesoporous materials nanoporous guanosine monophosphate material-1 (NGM-1) and nanoporous folic acid material-1 (NFM-1) for the enantiomeric separation of l- and d-valine. A pseudo-second-order (PSO) kinetic model is applied to test the experimental adsorption equilibrium isotherms, according to both the Langmuir and Freundlich models and the characteristic parameters for each model are determined. The calcined versions of both NGM-1 and NFM-1 fit the Langmuir model with maximum sorption capacities of 0.36 and 0.26 g/g for the preferred adsorption enantiomers, d-valine and l-valine, respectively. Experimental results and the analysis of adsorption models suggest a strong adsorbate–adsorbent interaction, and the formation of a monolayer of tightly packed amino acid on the internal mesopore surface for the preferred enantiomers.

Functional Systems Derived from Nucleobase Self-assembly

Dynamic and reversible non-covalent interactions endow synthetic systems and materials with smart adaptive functions that allow them to response to diverse stimuli, interact with external agents, or repair structural defects. Inspired by the outstanding performance and selectivity of DNA in living systems, scientists are increasingly employing Watson-Crick nucleobase pairing to control the structure and properties of self-assembled materials. Two sets of complementary purine-pyrimidine pairs (guanine:cytosine and adenine:thymine(uracil)) are available that provide selective and directional H-bonding interactions, present multiple metal-coordination sites, and exhibit rich redox chemistry. In this review, we highlight several recent examples that profit from these features and employ nucleobase interactions in functional systems and materials, covering the fields of energy/electron transfer, charge transport, adaptive nanoparticles, porous materials, macromolecule self-assembly, or polymeric materials with adhesive or self-healing ability.

Chiral Resolution using Supramolecular-Templated Mesostructured Materials

Chiral resolution using non-functionalized mesoporous particles is demonstrated for a variety of enantiomeric pairs. This is achieved through the use of supramolecular templated silica materials prepared with guanosine monophosphate (NGM-1) and folic acid (NFM-1) which enable direct chiral transcription onto the surface of the mesopores after solvent extraction and post calcination of the template. The chiral selectivity and kinetics of the mesoporous materials are measured by circular dichroism (CD) spectroscopy on adsorbed molecules with different affinities for the pore surface. NGM-1 and NFM-1 have opposite enantiomeric selectivity for enantiomeric pairs. These results significantly increase the potential of mesoporous materials for chiral separation and enantiomeric catalysis.

Directed Self-Assembly of C4-Symmetric, Oxidovanadate-Centered, Vanadyl(V) Quadruplexes for Ba2+- and Hg2+-Specific Recognition, Transport, and Recovery

Directed assembly of loosely, Na⁺-bound, oxidovanadate-centered quartets of C₄-symmetry from tailor-made chiral N-salicylidene-vanadyl(V) complexes, for the first time, allows for highly efficient Ba²⁺- or Hg²⁺-specific detection (by ⁵¹V NMR and VCD), transport (forming a unique helical capsule or a capped square planar complex, respectively), and green recovery from an aqueous phase containing 4 different alkaline earth ions or from at least 10 different metal ions of similar size and charge capacity into the CHCl₃ layer without interference from oxa- or oxophilic ions like Mg²⁺, Ca²⁺, Cu²⁺, Cd²⁺, and Pb²⁺.

G-Quadruplex DNA with an Apurinic Site as a Soft Molecularly Imprinted Sensing Platform

Molecularly imprinted polymers (MIPs) provide versatile sensor platforms to recognize targets by shape complementarity. However, the rigid structure of the classic MIPs compromises the signal transduction with necessary polymer and target modifications. Herein, we tried to use a flexible DNA that has a perfectly structured folding as the soft molecularly imprinted polymer (SMIP) for a straightforward sensor. As a proof of concept, the guanosine SMIP recognition was achieved by removal of a guanosine from a G-quadruplex-forming sequence (G4). The G4 folding structure with such an apurinic site (AP site) provides a well-defined MIP binding accommodation for guanosine according to the shape complementarity. The guanosine binding at the AP site subsequently leads to a conformation change suitable for remote readout using a G4-specific fluorescent ligand. The G4 sequence and AP site position were optimized for this SMIP behavior. Due to the G4 compact structure and the remaining hydrogen bonding pattern, nucleosides other than guanosine and negatively charged nucleotides exhibit no binding with the AP site, suggesting a high selectivity in the SMIP recognition. The proposed rationale was then convinced by the alkaline phosphatase-catalyzed GMP hydrolysis. Our work will inspire more interest in exploring nucleic acids as the SMIP frameworks due to their variant conformations and well-established molecular engineering.

Dispersed Uniform Nanoparticles from a Macroscopic Organosilica Powder

A colloidal dispersion of uniform organosilica nanoparticles could be produced via the disassembly of the non-surfactant-templated organosilica powder nanostructured folate material (NFM-1). This unusual reaction pathway was available because the folate and silica-containing moieties in NFM-1 are held together by noncovalent interactions. No precipitation was observed from the colloidal dispersion after a week, though particle growth occurred at a solvent-dependent rate that could be described by the Lifshitz-Slyozov-Wagner equation. An organosilica film that was prepared from the colloidal dispersion adsorbed folate-binding protein from solution but adsorbed ions from a phosphate-buffered saline solution to a larger degree. To our knowledge, this is the first instance of a colloidal dispersion of organosilica nanoparticles being derived from a macroscopic material rather than from molecular precursors.

Macrophage activation status determines the internalization of mesoporous silica particles of different sizes: Exploring the role of different pattern recognition receptors

Mesoporous silica-based particles are promising candidates for biomedical applications. Here, we address the importance of macrophage activation status for internalization of AMS6 (approx. 200 nm in diameter) versus AMS8 (approx. 2 μm) mesoporous silica particles and the role of different phagocytosis receptors for particle uptake. To this end, FITC-conjugated silica particles were used. AMS8 were found to be non-cytotoxic both for M-CSF-stimulated (anti-inflammatory) and GM-CSF-stimulated (pro-inflammatory) macrophages, whereas AMS6 exhibited cytotoxicity towards M-CSF-stimulated, but not GM-CSF-stimulated macrophages; this toxicity was, however, mitigated in the presence of serum. AMS8 triggered the secretion of pro-inflammatory cytokines in M-CSF-activated cells. Class A scavenger receptor (SR-A) expression was noted in both M-CSF and GM-CSF-stimulated macrophages, although the expression was higher in the former case, and gene silencing of SR-A resulted in a decreased uptake of AMS6 in the absence of serum. GM-CSF-stimulated macrophages expressed higher levels of the mannose receptor CD206 compared to M-CSF-stimulated cells, and uptake of AMS6, but not AMS8, was reduced following the downregulation of CD206 in GM-CSF-stimulated cells; particle uptake was also suppressed by mannan, a competitive ligand. These studies demonstrate that macrophage activation status is an important determinant of particle uptake and provide evidence for a role of different macrophage receptors for cell uptake of silica particles.

Transcription of G-quartet supramolecular aggregates into hierarchical mesoporous silica nanotubes

Hierarchical porous silica nanotubes or porous silica hollow spheres were prepared employing a low concentration of G-quartet supramolecular aggregates as a template.