The Bull-James assembly: Efficient iminoboronate complex formation for chiral derivatization and supramolecular assembly

BINOL as a Chiral Solvating Agent for Sulfiniminoboronic Acids

1H NMR spectroscopic studies using BINOL as a chiral solvating agent (CSA) for a scalemic sulfiniminoboronic acid (SIBA) have revealed concentration- and enantiopurity-dependent variations in the chemical shifts of diagnostic imine protons used to determine enantiopurity levels. 11B/15N NMR spectroscopic studies and X-ray structural investigations revealed that unlike other iminoboronate species, BINOL-SIBA assemblies do not contain N-B coordination bonds, with 1H NMR NOESY experiments indicating that intermolecular H-bonding networks between BINOL and the SIBA analyte are responsible for these variations. These effects can lead to diastereomeric signal overlap at certain er values that could potentially lead to enantiopurity/configuration misassignments. Consequently, it is recommended that hydrogen-bonding-CSA-based 1H NMR protocols should be repeated using both CSA enantiomers to ensure that any concentration- and/or er-dependent variations in diagnostic chemical shifts are accounted for when determining the enantiopurity of a scalemic analyte.

Dynamic covalent nano-networks comprising antibiotics and polyphenols orchestrate bacterial drug resistance reversal and inflammation alleviation

New antimicrobial strategies are urgently needed to meet the challenges posed by the emergence of drug-resistant bacteria and bacterial biofilms. This work reports the facile synthesis of antimicrobial dynamic covalent nano-networks (aDCNs) composing antibiotics bearing multiple primary amines, polyphenols, and a cross-linker acylphenylboronic acid. Mechanistically, the iminoboronate bond drives the formation of aDCNs, facilitates their stability, and renders them highly responsive to stimuli, such as low pH and high H₂O₂ levels. Besides, the representative A1B1C1 networks, composed of polymyxin B1(A1), 2-formylphenylboronic acid (B1), and quercetin (C1), inhibit biofilm formation of drug-resistant Escherichia coli, eliminate the mature biofilms, alleviate macrophage inflammation, and minimize the side effects of free polymyxins. Excellent bacterial eradication and inflammation amelioration efficiency of A1B1C1 networks are also observed in a peritoneal infection model. The facile synthesis, excellent antimicrobial performance, and biocompatibility of these aDCNs potentiate them as a much-needed alternative in current antimicrobial pipelines.

One-pot synthesis of dynamically cross-linked polymers for serum-resistant nucleic acid delivery

Cationic polymers used for nucleic acid delivery often suffer from complicated syntheses, undesired intracellular cargo release and low serum stability. Herein, a series of ternary polymers were synthesized via facile green chemistry to achieve efficient plasmid DNA and mRNA delivery in serum. During the one-pot synthesis of the ternary polymer, acetylphenylboric acid (APBA), polyphenol and low-molecular weight polyethyleneimine (PEI 1.8k) were dynamically cross-linked with each other due to formation of an imine between PEI 1.8k and APBA and formation of a boronate ester between APBA and polyphenol. Series of polyphenols, including ellagic acid (EA), epigallocatechin gallate (EGCG), nordihydroguaiaretic acid (NDGA), rutin (RT) and rosmarinic acid (RA), and APBA molecules, including 2-acetylphenylboric acid (2-APBA), 3-acetylphenylboric acid (3-APBA) and 4-acetylphenylboric acid (4-APBA), were screened and the best-performing ternary polymer, 2-PEI-RT, constructed from RT and 2-APBA, was identified. The ternary polymer featured efficient DNA condensation to favor cellular internalization, and the acidic environment in endolysosomes triggered effective degradation of the polymer to promote cargo release. Thus, 2-PEI-RT showed robust plasmid DNA transfection efficiencies in various tumor cells in serum, outperforming the commercial reagent PEI 25k by 1-3 orders of magnitude. Moreover, 2-PEI-RT mediated efficient cytosolic delivery of Cas9-mRNA/sgRNA to enable pronounced CRISPR-Cas9 genome editing in vitro. Such a facile and robust platform holds great potential for non-viral nucleic acid delivery and gene therapy.

Two-Tailed Dynamic Covalent Amphiphile Combats Bacterial Biofilms

Drug combination provides an efficient pathway to combat drug resistance in bacteria and bacterial biofilms. However, the facile methodology to construct the drug combinations and their applications in nanocomposites is still lacking. Here the two-tailed antimicrobial amphiphiles (T2 A2 ) composed of nitric oxide (NO)-donor (diethylenetriamine NONOate, DN) and various natural aldehydes are reported. T2 A2 self-assemble into nanoparticles due to their amphiphilic nature, with remarkably low critical aggregation concentration. The representative cinnamaldehyde (Cin)-derived T2 A2 (Cin-T2 A2 ) assemblies demonstrate excellent bactericidal efficacy, notably higher than free Cin and free DN. Cin-T2 A2 assemblies kill multidrug-resistant staphylococci and eradicate their biofilms via multiple mechanisms, as proved by mechanism studies, molecular dynamics simulations, proteomics, and metabolomics. Furthermore, Cin-T2 A2 assemblies rapidly eradicate bacteria and alleviate inflammation in the subsequent murine infection models. Together, the Cin-T2 A2 assemblies may provide an efficient, non-antibiotic alternative in combating the ever-increasing threat of drug-resistant bacteria and their biofilms.

Lipid Prodrug Nanoassemblies via Dynamic Covalent Boronates

Prodrug nanoassemblies combine the advantages of prodrug and nanomedicines, offering great potential in targeting the lesion sites and specific on-demand drug release, maximizing the therapeutic performance while minimizing their side effects. However, there is still lacking a facile pathway to prepare the lipid prodrug nanoassemblies (LPNAs). Herein, we report the LPNAs via the dynamic covalent boronate between catechol and boronic acid. The resulting LPNAs possess properties like drug loading in a dynamic covalent manner, charge reversal in an acidic microenvironment, and specific drug release at an acidic and/or oxidative microenvironment. Our methodology enables the encapsulation and delivery of three model drugs: ciprofloxacin, bortezomib, and miconazole. Moreover, the LPNAs are often more efficient in eradicating pathogens or cancer cells than their free counterparts, both in vitro and in vivo. Together, our LPNAs with intriguing properties may boost the development of drug delivery and facilitate their clinical applications.

The modern role of boron as a 'magic element' in biomedical science: chemistry perspective

Boron was misconstrued as a toxic element for animals, which retarded the growth of boron-containing drug discovery in the last century. Nevertheless, modern applications of boronic acid derivatives are attractive in biomedical applications after the declaration that boron is a 'probable essential element' for humans by the WHO. Additionally, the approval of five boronic acid-containing drugs by the FDA has vastly impacted the use of boron in medicinal chemistry, chemical biology, drug delivery, biomaterial exploration, pharmacological improvements, and nutrition. This review article focuses on the chemistries attributed to boronic acids at physiological pH, enticing chemists to multidisciplinary applications. Prospective uses of boronic acid in pharma and chemical biology, along with prospects and challenges, are also part of the deliberation. Understanding these fundamental chemistries and interactions of boronic acid in biological systems will enable solving future challenges in drug discovery and executing space-age applications.

Chiral recognition coupled with chemometrics using boronate ensembles containing D-π-A cyanostilbenes

Two types of boronic acid-appended D-π-A cyanostilbenes were synthesized to produce chiral boronate ensembles via dehydration with tartaric acid. The aggregation-induced high sensitivity and positional effect of the CN group on the emission properties allowed for chemometrics-coupled chiral recognition.

Fluorescent Sensor Array for Quantitative Determination of Saccharides

Accurate monitoring of sugar levels is essential for many fields from food industry to human health. Here, we developed FRET-based dual chromophore sensors for saccharides that form oxazolidine boronate and may be employed as a noninvasive method for monitoring of sugar levels in biological fluids, namely, urine. The saccharide-binding properties of the sensors were studied using fluorescence spectroscopy and utilized in the determination of saccharides in a high-throughput manner. Here, two fluorescent sensors were successful in the classification of nine different monosaccharides and disaccharides with 100% correct classification. Furthermore, the dual chromophore self-assembled sensors were successfully utilized for the quantitative determination of important carbohydrates such as glucose in the presence of competitive saccharides (fructose) and in complex media (urine) without sample pretreatment. The present fluorescent sensors allow for quantification of glucose in a concentration range of 0-60 mM, which matches the concentration range of frequently used urinalysis test strips.

Synthesis, structures and catalytic activity of some BINOL based boronates and boronium salts

The BINOL supported chiral boronate ester [C₁₀H₁₂O₂BC₆F₅(THF)] [(R)-1], [C₁₀H₁₂O₂BC₆F₅(O[double bond, length as m-dash]PEt₃)] [(R)-3] and [C₁₀H₁₂O₂BC₆F₅]₂ [(R,R)-2] as well as the chiral boronium salts [C₁₀H₁₂O₂B(O[double bond, length as m-dash]PEt₃)₂]⁺[B(O₂C₁₀H₁₂)₂]^-, [(R)-6] and [C₁₀H₁₂O₂B(O[double bond, length as m-dash]SMe₂)₂]⁺[B(O₂C₁₀H₁₂)₂]^- [(R)-7] have been synthesized, characterized by NMR spectroscopy, and the solid state structures of [(R)-1], [(R,R)-2] and [(R)-3] determined. Chiral ester [(R)-1] was found to be a potent Lewis acid, similar to B(C₆F₅)₃, and capable of rapidly catalyzing the annulation of (R)-, (S)- and rac-styrene oxide with nitrone PhCH[double bond, length as m-dash]N(O)Me to trans-2-methyl-3,6-diphenyl-1,4,2-dioxazine (trans-11) with high regio- and diastereoslectivities.

The influence of 2-acrylamidephenylboronic acid on the phase behaviour of its copolymers with N-isopropylacrylamide in aqueous solution

In this study, we report the synthesis and phase behaviour of statistical p(N-isopropylacrylamide-co-2-acrylamidephenylboronic acid), P(NIPAM-co-2-AAPBA) copolymers.