ChemBioChem最新文献

Gold nanoparticles (AuNPs) have emerged as powerful tools in the molecular sensing field for developing highly sensitive and selective molecular detection methods due to their unique properties, such as optical features and ease of surface modification. The core principle of AuNP-based sensors involves target molecule-induced aggregation, dispersion, or assembly of AuNPs through specific interactions with target molecules. These interactions cause changes in optical or electrochemical properties, which can be monitored through visible color shifts, surface-enhanced Raman scattering (SERS) signals, electrochemical techniques, and changes in scattering intensity. This review aims to highlight molecular detection strategies focusing on surface modification and aggregation mechanisms of AuNPs. It also introduces representative applications using colorimetric methods, SERS, electrochemical assays, and dark-field microscopy.

A phenyl urea unit is proposed as an aglet for completely favoring trans-Pro peptide bond, which is further stabilized by n → π* interaction. The urea-tagged Pro-Ile peptide is crystallized from nonaqueous solvent, and the X-ray structure analysis reveals self-assembly by clustering of hydrophobic side chains of Ile and phenyl ring, reminiscent of zipper structure found in coiled-coil peptides.

Cells are being utilized across various applications, including as self-regenerating materials, imaging and/or therapeutic entities, and delivery vehicles, and have the potential to do more. In biological and medical applications, specific cell types, including macrophages and mesenchymal stem cells (MSCs), have often been used on account of their recruitment to disease sites and desirable biodistribution properties. Typically, delivery applications involve the internalization of substrates within the cell, however, this approach presents drawbacks and is not amenable to some uses. Alternatively, chemically modifying cell surfaces using the toolbox of biocompatible chemistries has been broadly applied, but with few direct comparisons, including regarding assessment(s) of effects on the cells. In this work, we sought to compare commonly utilized N-hydroxysuccinimide ester and hydrazide-based conjugations to immortalized and primary macrophages and MSCs. We incorporated both small molecules and avidin proteins using each approach, finding that cargo size plays a substantial role in modifications. Overall, conjugations were well-tolerated by primary and immortalized macrophages and MSCs; we observed no major impacts on viability and chemotactic response, but found some slight changes and trends depending on cell and modification type. This foundational work directly comparing the results and effects of multiple conjugation strategies across different cell types will benefit their use across a variety of applications.

Fungal meroterpenoids, bioactive natural products with complex molecular frameworks, acquire their structural diversity partially through nonheme Fe(II)/α-ketoglutarate(αKG)-dependent enzymes. These enzymes use a high-valent Fe(IV)-oxo intermediate to drive diverse oxidative transformations. AndA, an Fe(II)/αKG oxygenase pivotal to anditomin biosynthesis, catalyzes regioselective C1C2 desaturation followed by skeletal rearrangement. While the isomerization step has been characterized, the mechanistic basis for desaturation over competing hydroxylation pathways remains enigmatic. Herein, molecular dynamics simulations and hybrid quantum mechanics/molecular mechanics calculations are employed to unravel how AndA avoids hydroxylation to achieve regioselective desaturation. The findings reveal the Fe(IV)-oxo intermediate, adopting two distinct coordination modes, a pentacoordinate (5C) and hexacoordinate (6C) geometry, differentiated by succinate coordination. The more reactive 5C species selectively abstracts the C2H hydrogen, initiating desaturation. Crucially, CO₂ generated in situ from αKG decarboxylation reacts with the resultant Fe(III)-OH complex, forming an Fe(III)-bicarbonate complex. This species sterically and electronically blocks OH rebound to the substrate. The Fe(III)-bicarbonate then abstracts a C1 hydrogen atom, completing the formation of the C1C2 double bond. These insights resolve the mechanism of AndA-catalyzed regioselective desaturation and demonstrate how CO₂-mediated coordination modulates oxidative fate, advancing mechanistic understanding of product control in this enzyme class.

Chitosan hydrogels are used in diverse applications ranging from pharmaceuticals and biomedical materials to food and agriculture. This study introduces a biology-inspired approach to create fully bio-based hydrogels by combining chitosan with bio-based di/polycarbonyl crosslinkers produced through the enzymatic oxidation of carbohydrates. Two such crosslinkers, Ox-XOS and Ox-Lac, were synthesized by oxidizing carbohydrates: Ox-XOS was produced by oxidizing xylooligosaccharides (XOS) with pyranose dehydrogenase from Agaricus bisporus (AbPDH1), and Ox-Lac was produced by oxidizing lactose (Lac) with galactose oxidase from Fusarium graminearum (FgrGalOx). The efficacy of enzymatic oxidation of lactose and XOS was analyzed using liquid chromatography and mass spectroscopy, showing high degrees of oxidation, and carbonyl groups were confirmed using ATR-FTIR and ¹H NMR. Compared with unmodified XOS, Ox-XOS showed a lower reaction temperature towards hexamethylenediamine by differential scanning calorimetry and demonstrated stronger gel formation ability with polyallylamine and chitosan. Rheological measurements showed $O\left(10\right)$ - $O\left({10}^3\right)$ increases in the storage moduli ( $G\text{'}$ ) of chitosan hydrogels formed with Ox-Lac and Ox-XOS compared with unmodified lactose and XOS, indicating considerable increases in the hydrogels' resistance to deformation. These findings demonstrate the potential of enzymatically oxidized carbohydrates as crosslinkers to enhance chitosan hydrogels with potential utility in both high-value and large-volume sectors.

Hybridising an Antimicrobial Peptide (AMP) with polyethylene glycol (PEG), to replace the peptide’s polyamide backbone by PEG, produces a Pegtide as an AMP mimetic. By analogy, the molecules are represented as combining the features of a bird (AMP) and a horse (PEG) in a winged horse (Pegasus) and folded to match the shapes of the Swan, Equuleus and Pegasus constellations, respectively. More details can be found in the Research Article by Marc Devocelle and co-workers (DOI: 10.1002/cbic.202500258).

The stability of aqueous two-phase system (ATPS) droplets is a key requirement for extending their utility beyond conventional applications, particularly as minimal models of biological cells and reaction compartments. However, the mechanisms by which their dynamic process in droplet size growth remain poorly understood. In this study, lecithin is demonstrated to effectively stabilize ATPS droplets by modulating two fundamental processes that determine their size evolution: 1) approaching migration driven by thermal motion and inter-droplet attraction and 2) the coalescence initiation time, defined as the delay between first contact and the onset of merging. Using dextran-rich droplets dispersed in a polyethylene glycol phase, significant suppression of both processes is shown that occurs only when lecithin concentrations exceed its critical micelle concentration. The findings indicate that lecithin coats droplet surfaces spontaneously to form a membrane-like layer, thereby reducing inter-droplet attraction and strongly inhibiting coalescence. This stabilization strategy offers a simple yet powerful means to control droplet dynamics, thereby opening up new possibilities for engineering ATPS droplets as versatile platforms for biochemical reactions and synthetic cell research.

A versatile and highly sensitive sensing platform has been developed by incorporating a nanocomposite of gold nanowire (AuNW), gold nanocolloid (AuNC), and polyacrylamide (PAA) onto the surface of a screen-printed carbon electrode (SPCE). This innovative approach is designed for the efficient detection of interleukin-6 (IL-6) in human serum and mammalian cell culture. The synthesized gold nanocomposite enhanced the SPCE's electrochemical signal via high conductivity, increased the electroactive surface for efficient electron transfer, and enabled thiolated aptamer immobilization through AuS bonds. In this regard, the AuNW/AuNC/PAA nanocomposite and thiolated IL-6 aptamers were used to construct an IL-6 aptasensor for sensitive and selective detection of IL-6 using differential pulse voltammetry (DPV) in 5 mM [Fe(CN)₆]^3-/4- as a redox probe. The fabricated aptasensor demonstrated sensitive detection of IL-6, with a detection range of 0.1-1000 pg mL^-1 and a limit of detection (LOD) of 0.1 pg mL^-1. Moreover, the developed IL-6 aptasensor exhibited excellent stability, reproducibility, and selectivity. Its applicability was validated by IL-6 detection in human serum, showing 93.9%-104.8% recovery. Additionally, IL-6 levels in cell culture media were tested using both the aptasensor and a commercial ELISA kit, showing only a 1.38% difference, further confirming its reliability.

Relaxin-3 is a two-chain neuropeptide of the insulin/relaxin superfamily and the cognate ligand for the G protein-coupled receptor RXFP3. Since its discovery, the relaxin-3/RXFP3 signaling system has emerged as a key regulator of feeding behavior, stress responses, arousal, addiction, and cognitive function. Recent structural studies, including the first cryo-electron microscopy structures of RXFP3 bound to relaxin-3 and small molecules, have provided significant insights into ligand-receptor interactions. Together with mutagenesis and pharmacological studies, these advances have facilitated the design of diverse RXFP3 ligands, ranging from simplified and/or stapled single-chain analogs of relaxin-3 to grafted scaffolds and small-molecule modulators. Such tools have been instrumental for probing relaxin-3 biology in vivo and highlight the system's therapeutic potential for treating anxiety, depression, obesity, binge eating, and alcohol use disorder. However, challenges remain, particularly regarding blood-brain barrier penetration, receptor subtype selectivity, pharmacokinetic optimization, and safe long-term modulation. This review summarizes current knowledge of relaxin-3 structure, receptor interactions, and pharmacology and highlights how advances in peptide chemistry, structural biology, and small-molecule design are enabling the rational development of RXFP3-targeted therapeutics.

Epinephrine (EPI), also known as adrenaline, is involved in various physiological processes of the sympathetic nervous system and may be linked to the progression of different serious diseases, including cancers, Alzheimer's, and Parkinson's diseases etc. There is an urgency in developing a fluorescence probe for the detection of EPI. An excited-state intramolecular proton transfer mechanism (ESIPT)-based reactive probe HBT-EPI has been successfully developed for ratiometric fluorescent detection of EPI in physiological conditions. EPI undergoes a cascade of nucleophilic attack at the carbonothioate site of the probe using the secondary amine and β-hydroxyl group to release the ESIPT-active 2-(2'-hydroxyphenyl) benzothiazole (HBT) fluorophore. Thus, a ratiometric fluorescence response is obtained. The probe is highly selective for EPI detection compared to other catecholamine-based neurotransmitters. A minimum of 1 µM of EPI can be easily detected using this probe. HBT-EPI has been successfully demonstrated for ratiometric fluorescence detection of EPI in live cells via confocal imaging.