No abstract

Alpha-toxin (AT) is a major virulence factor in the disease pathogenesis of Staphylococcus aureus. We previously identified a monoclonal antibody (MAb) against AT that reduced disease severity in a mouse dermonecrosis model. Here, we evaluate the activity of an affinity-optimized variant, LC10, in a mouse model of S. aureus pneumonia. Passive immunization with LC10 increased survival and reduced bacterial numbers in the lungs and kidneys of infected mice and showed protection against diverse S. aureus clinical isolates. The lungs of S. aureus-infected mice exhibited bacterial pneumonia, including widespread inflammation, whereas the lungs of mice that received LC10 exhibited minimal inflammation and retained healthy architecture. Consistent with reduced immune cell infiltration, LC10-treated animals had significantly lower (P < 0.05) proinflammatory cytokine and chemokine levels in the bronchoalveolar lavage fluid than did those of the control animals. This reduction in inflammation and damage to the LC10-treated animals resulted in reduced vascular protein leakage and CO 2 levels in the blood. LC10 was also assessed for its therapeutic activity in combination with vancomycin or linezolid. Treatment with a combination of LC10 and vancomycin or linezolid resulted in a significant increase (P < 0.05) in survival relative to the monotherapies and was deemed additive to synergistic by isobologram analysis. Consistent with improved survival, the lungs of animals treated with antibiotic plus LC10 exhibited less inflammatory tissue damage than those that received monotherapy. These data provide insight into the mechanisms of protection provided by AT inhibition and support AT as a promising target for immunoprophylaxis or adjunctive therapy against S. aureus pneumonia.

We present a net-shaped DNA nanostructure (called “DNA Net” herein) design strategy for selective recognition and high-affinity capture of intact SARS-CoV-2 virions through spatial pattern-matching and multivalent interactions between the aptamers (targeting wild-type spike-RBD) positioned on the DNA Net and the trimeric spike glycoproteins displayed on the viral outer surface. Carrying a designer nanoswitch, the DNA Net-aptamers release fluorescence signals upon virus binding that are easily read with a handheld fluorimeter for a rapid (in 10 min), simple (mix-and-read), sensitive (PCR equivalent), room temperature compatible, and inexpensive (∼$1.26/test) COVID-19 test assay. The DNA Net-aptamers also impede authentic wild-type SARS-CoV-2 infection in cell culture with a near 1 × 10 3 -fold enhancement of the monomeric aptamer. Furthermore, our DNA Net design principle and strategy can be customized to tackle other life-threatening and economically influential viruses like influenza and HIV, whose surfaces carry class-I viral envelope glycoproteins like the SARS-CoV-2 spikes in trimeric forms.

Metallic nanocube ensembles exhibit tunable localized surface plasmon resonance to induce the light manipulation at the subwavelength scale. Nevertheless, precisely control anisotropic metallic nanocube ensembles with relative spatial directionality remains a challenge. Here, we report a DNA origami based nanoprinting (DOBNP) strategy to transfer the essential DNA strands with predefined sequences and positions to the surface of the gold nanocubes (AuNCs). These DNA strands ensured the specific linkages between AuNCs and gold nanoparticles (AuNPs) that generating the stereo‐controlled AuNC‐AuNP nanostructures (AANs) with controlled geometry and composition. By anchoring the single dye molecule in hot spot regions, the dramatic enhanced electromagnetic field aroused stronger surface enhanced Raman scattering (SERS) signal amplification. Our approach opens the opportunity for the fabrication of stereo‐controlled metal nanostructures for designing highly sensitive photonic devices.

Self-assembled DNA nanostructures hold great promise as nanoscale templates for organizing nanoparticles (NPs) with near-atomistic resolution. However, large-scale organization of NPs with high yield is highly desirable for nanoelectronics and nanophotonic applications. Here, we design five-strand DNA tiles that can readily self-assemble into well-organized micrometer-scale DNA nanostructures. By organizing gold nanoparticles (AuNPs) on these self-assembled DNA nanostructures, we realize the fabrication of one- and two-dimensional Au nanostructures in single steps. We further demonstrate the one-pot synthesis of Au metamaterials for highly amplified surface-enhanced Raman Scattering (SERS). This single-step and high-yield strategy thus holds great potential for fabricating plasmonic metamaterials.

These authors contributed equally to this work. ABSTRACT DNA, when folded into nanostructures of customizable shapes, is capable of spacing and arranging external ligands in a desired geometric pattern with nanometer-precision. This allows DNA to serve as an excellent, biocompatible scaffold for complex spatial pattern-recognizing displays. In this report, we demonstrate that a templated designer DNA nanostructure achieves multi-ligand display with precise spatial pattern-recognition, representing a unique strategy in synthesizing potent viral sensors and inhibitors. Specifically, a star-shaped DNA architecture, carrying five molecular beacon-like motifs, was constructed to display ten dengue virus envelope protein domain-III (ED3)-binding aptamers into a 2D pattern precisely matching the pentagonal arrangement of ED3 clusters on the dengue viral surface. The resulting spatial pattern recognition and multivalent interactions achieve high dengue-binding avidity, conferring direct, highly-sensitive, facile, low-cost, and rapid sensing as well as potent viral inhibition capability. Our molecular-platform design strategy could be adapted to detect and combat other disease-causing pathogens, including bacteria and microbial-toxins, by generating the requisite ligand patterns on customized DNA nanoarchitectures.

Bacterial biofilm-related diseases cause serious hazard to public health and bring great challenge to the traditional antibiotic treatment. Photothermal therapy (PTT) has been recognized as a promising alternative solution. However, the therapeutic efficacy of PTT is often compromised by the collateral damage to normal tissues due to the lack of bacteria-targeting capability. Here, a Staphylococcus aureus (S. aureus)-targeted PTT nanoagent is prepared based on antibody (anti-protein A IgG), polydopamine (PDA), and PEG-SH (thiolated poly (ethylene glycol)) functionalized MoS2 nanosheets (MoS2@PDA-PEG/IgG NSs, MPPI NSs). The PDA was used as bio-nano interface to facilitate the covalent conjugation of antibody and PEG-SH onto the surface of MoS2 NSs via facile catechol chemistry. Targeted PTT of MPPI NSs shows excellent inactivation efficiency of larger than 4 log (>99.99%) to S. aureus both in biofilms (in vitro) and in infected tissues (in vivo) without causing damage to normal mammalian cells. By contrast, non-targeted PTT of MoS2@PDA-PEG NSs (MPP NSs) only kills S. aureus by <90% in vitro and <50% in vivo. As a result, S. aureus focal infection in mice healed much faster after PTT of MPPI NSs than that of MPP NSs. The superiority of targeted PTT may originate from the efficient accumulation and close binding of PTT agents to bacterial cells. Therefore, MPPI NSs with bacteria-targeting capability are promising photothermal agents for effective treatment of S. aureus focal infection.

MiRNAs are small regulatory RNAs that play crucial roles in the oncogenic state in various cancers and have shown highly promising clinical applications as plasma-based markers for cancer classification and prognostication. Due to their electroanalytical advantages, photoelectrochemical biosensors are a very attractive alternative technology for miRNA sensing and detection. In this work, we demonstrated a novel photoelectrochemical (PEC) sensor using the in situ grown Au nanoparticles/two-dimensional molybdenum disulfide (MoS2) nanosheet heterojunction (MoS2-AuNPs) on ITO glass as the photoanode (MoS2-AuNPs/ITO). AuNPs were used as a photoelectronic transfer promoter and DNA probe immobilization carrier as well. The thiol modified biotin DNA with a hairpin structure was tethered to the MoS2-AuNPs/ITO surface to form a specific capturing layer for miRNA detection. The biotin specific protein streptavidin was used as the signal amplifying species. This PEC sensor is structurally simple and possesses sensitivity and specificity toward miRNA. The CV and EIS responses were evaluated to monitor the PEC anode fabrication. The stability and reproducibility of this PEC design strategy were both evaluated before it was used in analyzing the samples of miRNA in human serum. Finally, we found that this PEC sensor displayed a broad detection linear range and a low detection limit of 4.21 fM, and it can excellently discriminate the mismatched miRNA. These findings pave the way for developing PEC sensors targeting miRNA by using noble metals/MoS2 heterojunctions.