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Bacterial infections are a serious ongoing threat to human health. As such, within the context of modern technology, there is an urgent need to develop fluorescent probes suitable for diagnosing bacterial infections in vivo. Herein, we synthesize NaGdF4:Nd@NaGdF4 core-shell down-conversion nanoparticles (DCNPs) demonstrating excellent emission intensity in the second near-infrared (NIR-II) window for use as fluorescent probes to enable high-quality imaging of pathogenic infections. The fluorescent probe is covalently linked with vancomycin (Van), which specifically binds to Gram-positive bacteria such as S. aureus. Both in vitro detection and in vivo imaging results show that the Van-modified NIR-II fluorescent probe can distinguish Gram-positive from Gram-negative bacteria with a high degree of selectivity. Biocompatibility is verified by MTT assay and histological analyses. [ABSTRACT FROM AUTHOR]

Addressing the global challenge of bacterial resistance demands innovative approaches, among which multitargeting is a widely used strategy. Current strategies of multitargeting, typically achieved through drug combinations or single agents inherently aiming at multiple targets, face challenges such as stringent pharmacokinetic and pharmacodynamic requirements and cytotoxicity concerns. In this report, we propose a bacterial-specific global disruption approach as a vastly expanded multitargeting strategy that effectively disrupts bacterial subcellular organization. This effect is achieved through a pioneering chemical design of ligand-receptor interaction-induced aggregation of small molecules, i.e ., DNA-induced aggregation of a diarginine peptidomimetic within bacterial cells. These intracellular aggregates display affinity toward various proteins and thus substantially interfere with essential bacterial functions and rupture bacterial cell membranes in an "inside-out" manner, leading to robust antibacterial activities and suppression of drug resistance. Additionally, biochemical analysis of macromolecule binding affinity, cytoplasmic localization patterns, and bacterial stress responses suggests that this bacterial-specific intracellular aggregation mechanism is fundamentally different from nonselective classic DNA or membrane binding mechanisms. These mechanistic distinctions, along with the peptidomimetic's selective permeation of bacterial membranes, contribute to its favorable biocompatibility and pharmacokinetic properties, enabling its in vivo antimicrobial efficacy in several animal models, including mice-based superficial wound models, subcutaneous abscess models, and septicemia infection models. These results highlight the great promise of ligand-receptor interaction-induced intracellular aggregation in achieving a globally disruptive multitargeting effect, thereby offering potential applications in the treatment of malignant cells, including pathogens, tumor cells, and infected tissues.

Ship emissions are a significant source of air pollution, and the primary policy to control is fuel oil quality improvement. However, the impact of this policy on particle size distribution and composition characteristics remains unclear. Measurements were conducted on nine different vessels (ocean-going vessels, coastal cargo ships, and inland cargo ships) to determine the impact of fuel upgrading ( S < 0.1% m/m marine gas oil (MGO) vs S < 0.5% m/m heavy fuel oil (HFO)) on elemental carbon (EC) and polycyclic aromatic hydrocarbons (PAHs) emitted by ships. (1) Fuel improvement significantly reduced EC and PAH emission, by 31 ± 25 and 45 ± 38%, respectively. However, particle size distributions showed a trend toward finer particles, with the peak size decreasing from D P = 0.38-0.60 μm (HFO) to D P = 0.15-0.25 μm (MGO), and the emission factor of D P < 100 nm increased. (2) Changes in emission characteristics led to an increase in the toxicity of ultrafine particulate matter. (3) Ship types and engine conditions affected the EC and PAH particle size distributions. Inland ships have a more concentrated particle size distribution. Higher loads result in higher emissions. (4) The composition and engine conditions of fuel oils jointly affected pollutant formation mechanisms. MGO and HFO exhibited opposite EC emissions when emitting the same level of PAHs.

High-throughput screening (HTS) is pivotal in the discovery of small molecules that bind to DNA, yet there are limited sensing mechanisms available for designing HTS assays for DNA binders. Herein, we introduce a binder-responsive toehold-mediated DNA strand displacement (BR-TMSD) technique featuring programmable reaction kinetics in response to DNA-binder interactions. When two DNA binders are used, BR-TMSD is initiated through a rapid binder displacement, followed by the DNA strand displacement. The orthogonal displacement reactions of BR-TMSD enables a high-fidelity, dual-channel HTS assay, returning 19 new DNA binders from a library of 1,170 compounds.

δ 18 O is widely used to track nitrate (NO 3 - ) formation but overlooks NO 3 radical reactions with hydrocarbons (HCs), particularly in heavily emitting hazes. This study introduces high-time resolution Δ 17 O-NO 3 - as a powerful tool to quantify NO 3 - formation during five hazes in three cities. Results show significant differences between Δ 17 O-NO 3 - and δ 18 O-NO 3 - in identifying NO 3 - formation. δ 18 O-NO 3 - results suggested N 2 O 5 hydrolysis (62.0-88.4%) as the major pathway of NO 3 - formation, while Δ 17 O-NO 3 - shows the NO 3 - formation contributions of NO 2 + OH (17.7-66.3%), NO 3 + HC (10.8-49.6%), and N 2 O 5 hydrolysis (22.9-33.3%), revealing significant NO 3 + HC contribution (41.7-56%) under severe pollution. Furthermore, NO 3 - formation varies with temperatures, NO x oxidation rate (NOR), and pollution levels. Higher NO 2 + OH contribution and lower NO 3 + HC contribution were observed at higher temperatures, except for low NOR haze where higher NO 2 + OH contributions were observed at low temperatures ( T ← 10 °C). This emphasizes the significance of NO 2 + OH in emission-dominated haze. Contributions of NO 2 + OH and NO 3 + HC relate to NOR as positive ( f P1 = 3.0*NOR 2 - 2.4*NOR + 0.8) and negative ( f P2 = -2.3*NOR 2 + 1.8*NOR) quadratic functions, respectively, with min/max values at NOR = 0.4. At mild pollution, NO 2 + OH (58.1 ± 22.2%) dominated NO 3 - formation, shifting to NO 3 + HC (35.5 ± 16.3%) during severe pollution. Additionally, high-time resolution Δ 17 O-NO 3 - reveals that morning-evening rush hours and high temperatures at noon promote the contributions of NO 3 + HC and NO 2 + OH, respectively. Our results suggested that the differences in the NO 3 - pathway are attributed to temperatures, NOR, and pollution levels. Furthermore, high-time resolution Δ 17 O-NO 3 - is vital for quantifying NO 3 + HC contribution during severe hazes.

A material system enabling specific NIR-II fluorescence imaging of Gram-positive bacteria is described. The material system is based on the electrostatic binding of Cu 2- x Se and vancomycin-modified NaGdF 4 :Nd,Yb@NaGdF 4 downconversion nanoparticles (DCNPs), the fluorescence of which is weak owing to the spectral overlap of Cu 2- x Se absorption with the DCNP NIR emission. The presence of Gram-positive bacteria precisely disconnects the bond between vancomycin-modified DCNPs and Cu 2- x Se, thus enabling a strong fluorescent signal. In vivo studies show that the material system can be specifically activated at the site of Gram-positive bacterial infection but is essentially nonfluorescent in the area of Gram-negative bacterial infection.

Gram-negative bacteria, especially the ones with multidrug resistance, post dire challenges to antibiotic treatments due to the presence of the outer membrane (OM), which blocks the entry of many antibiotics. Current solutions for such permeability issues, namely lipophilic-cationic derivatization of antibiotics and sensitization with membrane-active agents, cannot effectively potentiate the large, globular, and hydrophilic antibiotics such as vancomycin, due to ineffective disruption of the OM. Here, we present our solution for high-degree OM binding of vancomycin via a hybrid "derivatization-for-sensitization" approach, which features a combination of LPS-targeting lipo-cationic modifications on vancomycin and OM disruption activity from a sensitizing adjuvant. 10 6 - to 10 7 -fold potentiation of vancomycin and 20-fold increase of the sensitizer's effectiveness were achieved with a combination of a vancomycin derivative and its sensitizer. Such potentiation is the result of direct membrane lysis through cooperative membrane binding for the sensitizer-antibiotic complex, which strongly promotes the uptake of vancomycin and adds to the extensive antiresistance effectiveness. The potential of such derivatization-for-sensitization approach was also supported by the combination's potent in vivo antimicrobial efficacy in mouse model studies, and the expanded application of such strategy on other antibiotics and sensitizer structures.

Bisphosphonates are a major class of drugs used to treat osteoporosis, Paget's disease, and cancer. They have been proposed to act by inhibiting one or more targets including protein prenylation, the epidermal growth factor receptor, or the adenine nucleotide translocase. Inhibition of the latter is due to formation in cells of analogs of ATP: the isopentenyl ester of ATP (ApppI) or an AppXp-type analog of ATP, such as AMP-clodronate (AppCCl 2 p). We screened both ApppI as well as AppCCl 2 p against a panel of 369 kinases finding potent inhibition of some tyrosine kinases by AppCCl 2 p, attributable to formation of a strong hydrogen bond between tyrosine and the terminal phosphonate. We then synthesized bisphosphonate preprodrugs that are converted in cells to other ATP-analogs, finding low nM kinase inhibitors that inhibited cell signaling pathways. These results help clarify our understanding of the mechanisms of action of bisphosphonates, potentially opening up new routes to the development of bone resorption, anticancer, and anti-inflammatory drug leads.

We synthesized a series of polyoxometalate-bisphosphonate complexes containing Mo VI O 6 octahedra, zoledronate, or an N-alkyl (n-C 6 or n-C 8 ) zoledronate analogue, and in two cases, Mn as a heterometal. Mo 6 L 2 (L = Zol, ZolC 6 , ZolC 8 ) and Mo 4 L 2 Mn (L = Zol, ZolC 8 ) were characterized by using single-crystal X-ray crystallography and/or IR spectroscopy, elemental and energy dispersive X-ray analysis and 31 P NMR. We found promising activity against human nonsmall cell lung cancer (NCI-H460) cells with IC 50 values for growth inhibition of ∼5 μM per bisphosphonate ligand. The effects of bisphosphonate complexation on IC 50 decreased with increasing bisphosphonate chain length: C 0 ≈ 6.1×, C 6 ≈ 3.4×, and C 8 ≈ 1.1×. We then determined the activity of one of the most potent compounds in the series, Mo 4 Zol 2 Mn(III), against SK-ES-1 sarcoma cells in a mouse xenograft system finding a ∼5× decrease in tumor volume than found with the parent compound zoledronate at the same compound dosing (5 μg/mouse). Overall, the results are of interest since we show for the first time that heteropolyoxomolybdate-bisphosphonate hybrids kill tumor cells in vitro and significantly decrease tumor growth, in vivo, opening up new possibilities for targeting both Ras as well as epidermal growth factor receptor driven cancers.

We show that copper-containing metal-organic nanoparticles (MONPs) are readily synthesized via Cu(II)-mediated intramolecular cross-linking of aspartate-containing polyolefins in water. In situ reduction with sodium ascorbate yields Cu(I)-containing MONPs that serve as highly efficient supramolecular catalysts for alkyne-azide "click chemistry" reactions, yielding the desired 1,4-adducts at low parts per million catalyst levels. The nanoparticles have low toxicity and low metal loadings, making them convenient, green catalysts for alkyne-azide "click" reactions in water. The Cu-MONPs enter cells and perform efficient, biocompatible click chemistry, thus acting as intracellular nanoscale molecular synthesizers.

The functional groups displayed on the surface of nanoparticles (NP) are known to play an important role in NP cellular uptake. However, only a few systematic studies have been reported to address their role, in large part because of the difficulty in regularly varying the number and structure of the functional groups on the NP surface. We employ a bottom-up strategy for the synthesis of water-soluble organic nanoparticles (ONPs) with different sizes and functional groups, using readily available monomers. Utilizing flow cytometry, we measured the HeLa cell uptake efficiency of ONPs that contain side-chains with a different (a) length, (b) number of hydroxyl groups, and (c) number of methyl groups. We have also investigated ONPs with the same functional groups but different sizes. The potential formation and influence of protein corona was examined using the same approach but in the presence of serum. The results demonstrate that under both serum and serum-free conditions the surface-exposed functional groups determine the efficiency of cellular uptake of the particles, and that the trend can be partially predicted by the lipophilicity of the polymeric ONP's repeating units. Also, by using a "masking" strategy, these particles' cellular uptake behavior could be altered conveniently.

We report the discovery of a series of new drug leads that have potent activity against Mycobacterium tuberculosis as well as against other bacteria, fungi, and a malaria parasite. The compounds are analogues of the new tuberculosis (TB) drug SQ109 (1), which has been reported to act by inhibiting a transporter called MmpL3, involved in cell wall biosynthesis. We show that 1 and the new compounds also target enzymes involved in menaquinone biosynthesis and electron transport, inhibiting respiration and ATP biosynthesis, and are uncouplers, collapsing the pH gradient and membrane potential used to power transporters. The result of such multitarget inhibition is potent inhibition of TB cell growth, as well as very low rates of spontaneous drug resistance. Several targets are absent in humans but are present in other bacteria, as well as in malaria parasites, whose growth is also inhibited.

We have obtained the structure of the bacterial diterpene synthase, tuberculosinol/iso-tuberculosinol synthase (Rv3378c) from Mycobacterium tuberculosis , a target for anti-infective therapies that block virulence factor formation. This phosphatase adopts the same fold as found in the Z- or cis-prenyltransferases. We also obtained structures containing the tuberculosinyl diphosphate substrate together with one bisphosphonate inhibitor-bound structure. These structures together with the results of site-directed mutagenesis suggest an unusual mechanism of action involving two Tyr residues. Given the similarity in local and global structure between Rv3378c and the M. tuberculosis cis-decaprenyl diphosphate synthase (DPPS; Rv2361c), the possibility exists for the development of inhibitors that target not only virulence but also cell wall biosynthesis, based in part on the structures reported here.