Switching of electrochemical selectivity due to plasmonic field-induced dissociation.

Electrochemical reactivity is known to be dictated by the structure and composition of the electrocatalyst-electrolyte interface. Here, we show that optically generated electric fields at this interface can influence electrochemical reactivity insofar as to completely switch reaction selectivity. We study an electrocatalyst composed of gold-copper alloy nanoparticles known to be active toward the reduction of CO2 to CO. However, under the action of highly localized electric fields generated by plasmonic excitation of the gold-copper alloy nanoparticles, water splitting becomes favored at the expense of CO2 reduction. Real-time time-dependent density functional tight binding calculations indicate that optically generated electric fields promote transient-hole-transfer-driven dissociation of the O─H bond of water preferentially over transient-electron-driven dissociation of the C─O bond of CO2. These results highlight the potential of optically generated electric fields for modulating pathways, switching reactivity on/off, and even directing outcomes.

Caged AIEgens: Multicolor and White Emission Triggered by Mechanical Activation.

Aggregation-induced emission luminogens (AIEgens) that respond to mechanical force are increasingly used as force probes, memory devices, and advanced security systems. Most of the known mechanisms to modulate mechanoresponsive AIEgens have been based on changes in aggregation states, involving only physical alterations. Instances that employ covalent bond cleavage are still rare. We have developed a novel mechanochemical uncaging strategy to unveil AIEgens with diverse emission characteristics using engineered norborn-2-en-7-one (NEO) mechanophores. These NEO mechanophores were covalently integrated into polymer molecules and activated in both the solution and solid states. This activation resulted in highly tunable fluorescence upon immobilization through solidification or aggregation, producing blue, green, yellow, and orange-red emissions. By designing the caged and uncaged forms as donor-acceptor pairs for Förster resonance energy transfer (FRET), we achieved multicolor mechanofluorescence, effectively broadening the color spectrum to include white emission. Additionally, we computationally explored the electronic structures of activated NEOs, providing insights into the observed regiochemical effects of the substituents. This understanding, together with the novel luminogenic characteristics of the caged and activated species, provides a highly tunable reporter that traces progress with continuous color evolution. This advancement paves the way for future applications of mechanoresponsive materials in areas like damage detection and bioimaging.

Impedimetric Characterization of NanA Structural Domains Activity on Sialoside-Containing Interfaces.

Streptococcus pneumoniae is a pathogenic bacterium that contains the surface-bound neuraminidase, NanA. NanA has two domains that interact with sialosides. It is hard to determine the contribution of each domain separately on catalysis or binding. In this work, we used biochemical methods to obtain the separated domains, applied electrochemical and surface analysis approaches, and determined the catalytic and binding preferences toward a surface-bound library of sialosides. Impedimetric studies on two different surfaces revealed that protein-surface interactions provide a tool for distinguishing the unique contribution of each domain at the interface affecting the substrate preference of the enzyme in different surroundings. We showed that each domain has a sialoside-specific affinity. Furthermore, while the interaction of the sialoside-covered surface with the carbohydrate-binding domain results in an increase in impedance and binding, the catalytic domain adheres to the surface at high concentrations but retains its catalytic activity at low concentrations.

Surface-Controlled Sialoside-Based Biosensing of Viral and Bacterial Neuraminidases.

Neuraminidases (NA) are sialic acid-cleaving enzymes that are used by both bacteria and viruses. These enzymes have sialoside structure-related binding and cleaving preferences. Differentiating between these enzymes requires using a large array of hard-to-access sialosides. In this work, we used electrochemical impedimetric biosensing to differentiate among several pathogene-related NAs. We used a limited set of sialosides and tailored the surface properties. Various sialosides were grafted on two different surfaces with unique properties. Electrografting on glassy carbon electrodes provided low-density sialoside-functionalized surfaces with a hydrophobic submonolayer. A two-step assembly on gold electrodes provided a denser sialoside layer on a negatively charged submonolayer. The synthesis of each sialoside required dozens of laborious steps. Utilizing the unique protein-electrode interaction modes resulted in richer biodata without increasing the synthetic load. These principles allowed for profiling NAs and determining the efficacy of various antiviral inhibitors.

Outcome of Open Repair of Thoracoabdominal Aortic Aneurysm in Takayasu Arteritis: A Retrospective Analysis.

BACKGROUND: Takayasu Arteritis (TA) is an immune mediated arteritis causing inflammation of the aorta and its branches, which can result in aortic aneurysms. Our aim is to describe the outcome of surgical management in these patients who presented with Thoracoabdominal aortic aneurysm (TAAA). METHODS: Between 2003 and 2023, 40 TA patients with TAAA underwent operative repair. RESULTS: There were 24 females and 16 males, in the age group of 19-53 years, with hypertension in 20 patients. Raised Erythrocyte sedimentation Rate was present in 13 patients. According to Crawford classification, there were 2 patients with type I, 2 with type II, 17 with type III, 12 patients with type IV and 7 with type V aneurysm. Multiple steno-occlusive lesions of aortic branches were present in 21 patients, with majority affecting the renal artery. Femoral Artery Femoral Vein Partial cardiopulmonary bypass was used for types I, II, III and V. Separate bypass to visceral branches was done in eight patients, of whom five had multiple bypasses and three patients only had renal bypass. Twelve patients underwent reimplantation of branches, out of which nine had multiple vessel reimplantation. Four patients underwent staged repair of the aneurysm, which included visceral debranching in the first day, followed by repair of the aneurysm in the next day. In the immediate postoperative period, ten patients developed acute kidney injury and two required dialysis. Other morbidities included acute respiratory distress syndrome (ARDS), spinal cord dysfunction, bleeding, and wound complications. Three patients expired in the immediate postoperative period. Mean duration of intensive care unit stay was 4.1 days and hospital stay was 12.7 days. Comparison of disease activity with morbidity and mortality was statistically insignificant. Patients were on follow-up for a range of 6 months to 14 years and median follow-up of 25 months. Over this time period four patients expired and four developed anastomotic pseudoaneurysm requiring intervention. On comparing the disease activity at the time of surgery with the long-term arteritis related complications that required intervention, the P value was 0.653 and hence statistically not significant. The 10-year survival rate is 84.4%. CONCLUSIONS: Surgical repair has good and satisfactory outcome, with low early and late mortality rates. Progression of disease can occur at any stage of the disease, hence indicating the need for long term follow-up and frequent imaging.

In Situ Electron Microscopy of Transformations of Copper Nanoparticles under Plasmonic Excitation.

Metal nanoparticles are attracting interest for their light-absorption properties, but such materials are known to dynamically evolve under the action of chemical and physical perturbations, resulting in changes in their structure and composition. Using a transmission electron microscope equipped for optical excitation of the specimen, the structural evolution of Cu-based nanoparticles under simultaneous electron beam irradiation and plasmonic excitation was investigated with high spatiotemporal resolution. These nanoparticles initially have a Cu core-Cu2O oxide shell structure, but over the course of imaging, they undergo hollowing via the nanoscale Kirkendall effect. We captured the nucleation of a void within the core, which then rapidly grows along specific crystallographic directions until the core is hollowed out. Hollowing is triggered by electron-beam irradiation; plasmonic excitation enhances the kinetics of the transformation likely by the effect of photothermal heating.

Nucleoside-Driven Specificity of DNA Methyltransferase.

We have studied the adenosine binding specificities of two bacterial DNA methyltransferases, Taq methyltransferase (M.TaqI), and HhaI methyltransferase (M.HhaI). While they have similar cofactor binding pocket interactions, experimental data showed different specificity for novel S-nucleobase-l-methionine cofactors (SNMs; N=guanosyl, cytidyl, uridyl). Protein dynamics corroborate the experimental data on the cofactor specificities. For M.TaqI the specificity for S-adenosyl-l-methionine (SAM) is governed by the tight binding on the nucleoside part of the cofactor, while for M.HhaI the degree of freedom of the nucleoside chain allows the acceptance of other bases. The experimental data prove catalytically productive methylation by the M.HhaI binding pocket for all the SNMs. Our results suggest a new route for successful design of unnatural SNM analogues for methyltransferases as a tool for cofactor engineering.

Neoadjuvant Management of Adenocarcinoma of the Esophagus and Esophagogastric Junction: Review of Randomized Evidence and Definition of Optimum Treatment Algorithm.

BACKGROUND: Neoadjuvant chemotherapy (nCT) or chemoradiotherapy (nCRT) are accepted standards of care for the management of adenocarcinoma of the esophagus and gastroesophageal junction. SUMMARY: The MRC-OEO2 study established the role of 2 cycles of neoadjuvant cisplatin/fluoropyrimidine. More recently, the FLOT-AIO4 study demonstrated the superiority of perioperative FLOT chemotherapy (5FU, oxaliplatin, and docetaxel) compared to ECX (epirubicin, cisplatin, and capecitabine) regime. The results from the pivotal CROSS study established neoadjuvant CRT as a new standard of care in OG cancer. The survival benefits observed in FLOT and CROSS studies are similar [FLOT - hazard ratio 0.75 (0.62-0.92); CROSS - 0.741 (0.55-0.98)]. KEY MESSAGES: Both nCT and nCRT have been shown to be associated with survival benefit compared to surgery alone. We have performed a comprehensive review of the available evidence to define the optimum treatment algorithm and identify specific patient sub-groups who may be appropriate for the use of one or more of these neoadjuvant options.

Hot Carrier Lifetimes and Electrochemical Water Dissociation Enhanced by Nickel Doping of a Plasmonic Electrocatalyst.

Hot carriers generated by localized surface plasmon resonance (LSPR) excitation of plasmonic metal nanoparticles are known to enhance electrocatalytic reactions. However, the participation of plasmonically generated carriers in interfacial electrochemical reactions is often limited by fast relaxation of these carriers. Herein, we address this challenge by tuning the electronic structure of a plasmonic electrocatalyst. Specifically, we design an electrocatalyst for alkaline hydrogen evolution reaction (HER) that consists of nanoparticles of a ternary Cu-Pt-Ni ternary alloy. The CuPt alloy has both plasmonic attributes and electrocatalytic HER activity. Ni doping contributes an electron-deficient 3d band and fully filled 4s band, which promotes water adsorption and prolongs the lifetimes of excited carriers generated by plasmonic excitation. As an outcome, the Cu-Pt-Ni nanoparticles exhibit boosted activity for electrochemical water dissociation and HER under LSPR excitation.

Plasmon-Assisted Ammonia Electrosynthesis.

Ammonia is a promising liquid-phase carrier for the storage, transport, and deployment of carbon-free energy. However, the realization of an ammonia economy is predicated on the availability of green methods for the production of ammonia powered by electricity from renewable sources or by solar energy. Here, we demonstrate the synthesis of ammonium from nitrate powered by a synergistic combination of electricity and light. We use an electrocatalyst composed of gold nanoparticles, which have dual attributes of electrochemical nitrate reduction activity and visible-light-harvesting ability due to their localized surface plasmon resonances. Plasmonic excitation of the electrocatalyst induces ammonium synthesis with up to a 15× boost in activity relative to conventional electrocatalysis. We devise a strategy to account for the effect of photothermal heating of the electrode surface, which allows the observed enhancement to be attributed to non-thermal effects such as energetic carriers and charged interfaces induced by plasmonic excitation. The synergy between electrochemical activation and plasmonic activation is the most optimal at a potential close to the onset of nitrate reduction. Plasmon-assisted electrochemistry presents an opportunity for conventional limits of electrocatalytic conversion to be surpassed due to non-equilibrium conditions generated by plasmonic excitation.

Profiling Heparan Sulfate-Heavy Metal Ions Interaction Using Electrochemical Techniques.

Heparan sulfate glycosaminoglycans provides extracellular matrix defense against heavy metals cytotoxicity. Identifying the precise glycan sequences that bind a particular heavy metal ion is a key for understanding those interactions. Here, electrochemical and surface characterization techniques were used to elucidate the relation between the glycans structural motifs, uronic acid stereochemistry, and sulfation regiochemistry to heavy metal ions binding. A divergent strategy was employed to access a small library of structurally well-defined tetrasaccharides analogs with different sulfation patterns and uronic acid compositions. These tetrasaccharides were electrochemically grafted onto glassy carbon electrodes and their response to heavy metal ions was monitored by electrochemical impedance spectroscopy. Key differences in the binding of Hg(II), Cd(II), and Pb(II) were associated with a combination of the uronic acid type and the sulfation pattern.

Control of Chemical Reaction Pathways by Light-Matter Coupling.

Because plasmonic metal nanostructures combine strong light absorption with catalytically active surfaces, they have become platforms for the light-assisted catalysis of chemical reactions. The enhancement of reaction rates by plasmonic excitation has been extensively discussed. This review focuses on a less discussed aspect: the induction of new reaction pathways by light excitation. Through commentary on seminal reports, we describe the principles behind the optical modulation of chemical reactivity and selectivity on plasmonic metal nanostructures. Central to these phenomena are excited charge carriers generated by plasmonic excitation, which modify the energy landscape available to surface reactive species and unlock pathways not conventionally available in thermal catalysis. Photogenerated carriers can trigger bond dissociation or desorption in an adsorbate-selective manner, drive charge transfer and multielectron redox reactions, and generate radical intermediates. Through one or more of these mechanisms, a specific pathway becomes favored under light. By improved control over these mechanisms, light-assisted catalysis can be transformational for chemical synthesis and energy conversion.

Motion of Defects in Ion-Conducting Nanowires.

Superionic conductors are prime candidates for the electrolytes of all-solid-state batteries. Our understanding of the mechanism and performance of superionic conductors is largely based on their idealized lattice structures. But how do defects in the lattice affect ionic structure and transport in these materials? This is a question answered here by in situ transmission electron microscopy of copper selenide, a classic superionic conductor. Nanowires of copper selenide exhibit antiphase boundaries which are a form of a planar defect. We examine the lattice structure around an antiphase boundary and monitor with atomic resolution how this structure evolves in an ordered-to-superionic phase transition. Antiphase boundaries are found to act as barriers to the propagation of the superionic phase. Antiphase boundaries also undergo spatial diffusion and shape changes resulting from thermally activated fluctuations of the neighboring ionic structure. These spatiotemporal insights highlight the importance of collective ionic transport and the role of defects in superionic conduction.

Light-Induced Voltages in Catalysis by Plasmonic Nanostructures.

ConspectusPlasmonic nanostructures have garnered widescale scientific interest because of their strong light-matter interactions and the tunability of their absorption across the solar spectrum. At the heart of their superlative interaction with light is the resonant excitation of a collective oscillation of electrons in the nanostructure by the incident electromagnetic field. These resonant oscillations are known as localized surface plasmon resonances (LSPRs). In recent years, the community has uncovered intriguing photochemical attributes of noble metal nanostructures arising from their LSPRs. Chemical reactions that are otherwise unfavorable or sluggish in the dark are induced on the nanostructure surface upon photoexcitation of LSPRs. This phenomenon has led to the birth of plasmonic catalysis. The rates of a variety of kinetically challenging reactions are enhanced by plasmon-excited nanostructures. While the potential utility for solar energy harvesting and chemical production is clear, there is a natural curiosity about the precise origin(s) of plasmonic catalysis. One explanation is that the reactions are facilitated by the action of the intensely concentrated and confined electric fields generated on the nanostructure upon LSPR excitation. Another mechanism of activation involves hot carriers transiently produced in the metal nanostructure by damping of LSPRs.In this Account, we visit a phenomenon that has received less attention but has a key role to play in plasmonic catalysis and chemistry. Under common chemical scenarios, plasmonic excitation induces a potential or a voltage on a nanoparticle. This photopotential modifies the energetics of a chemical reaction on noble metal nanoparticles. In a range of cases studied by our laboratory and others, light-induced potentials underlie the plasmonic enhancement of reaction kinetics. The photopotential model does not replace other known mechanisms, but it complements them. There are multiple ways in which an electrostatic photopotential is produced by LSPR excitation, such as optical rectification, but one that is most relevant in chemical media is asymmetric charge transfer to solution-phase acceptors. Electrons and holes produced in a nanostructure by damping of LSPRs are not removed at the same rate. As a result, the slower carrier accumulates on the nanostructure, and a steady-state charge is built up on the nanostructure, leading to a photopotential. Potentials of up to a few hundred millivolts have been measured by our laboratory and others. A photocharged nanoparticle is a source of carriers of a higher potential than an uncharged one. As a result, redox chemical reactions on noble metal nanoparticles exhibit lower activation barriers under photoexcitation. In electrochemical reactions on noble metal nanoparticles, the photopotential supplements the applied potential. In a diverse set of reactions, the photopotential model explains the photoenhancement of rates as well as the trends as a function of light intensity and photon energy. With further gains, light-induced potentials may be used as a knob for controlling the activities and selectivities of noble metal nanoparticle catalysts.

Roadmap on quantum nanotechnologies.

Quantum phenomena are typically observable at length and time scales smaller than those of our everyday experience, often involving individual particles or excitations. The past few decades have seen a revolution in the ability to structure matter at the nanoscale, and experiments at the single particle level have become commonplace. This has opened wide new avenues for exploring and harnessing quantum mechanical effects in condensed matter. These quantum phenomena, in turn, have the potential to revolutionize the way we communicate, compute and probe the nanoscale world. Here, we review developments in key areas of quantum research in light of the nanotechnologies that enable them, with a view to what the future holds. Materials and devices with nanoscale features are used for quantum metrology and sensing, as building blocks for quantum computing, and as sources and detectors for quantum communication. They enable explorations of quantum behaviour and unconventional states in nano- and opto-mechanical systems, low-dimensional systems, molecular devices, nano-plasmonics, quantum electrodynamics, scanning tunnelling microscopy, and more. This rapidly expanding intersection of nanotechnology and quantum science/technology is mutually beneficial to both fields, laying claim to some of the most exciting scientific leaps of the last decade, with more on the horizon.

Nanoscale optical imaging in chemistry.

Single-molecule-level measurements are bringing about a revolution in our understanding of chemical and biochemical processes. Conventional measurements are performed on large ensembles of molecules. Such ensemble-averaged measurements mask molecular-level dynamics and static and dynamic fluctuations in reactivity, which are vital to a holistic understanding of chemical reactions. Watching reactions on the single-molecule level provides access to this otherwise hidden information. Sub-diffraction-limited spatial resolution fluorescence imaging methods, which have been successful in the field of biophysics, have been applied to study chemical processes on single-nanoparticle and single-molecule levels, bringing us new mechanistic insights into physiochemical processes. However, the scope of chemical processes that can be studied using fluorescence imaging is considerably limited; the chemical reaction has to be designed such that it involves fluorophores or fluorogenic probes. In this article, we review optical imaging modalities alternative to fluorescence imaging, which expand greatly the range of chemical processes that can be probed with nanoscale or even single-molecule resolution. First, we show that the luminosity, wavelength, and intermittency of solid-state photoluminescence (PL) can be used to probe chemical transformations on the single-nanoparticle-level. Next, we highlight case studies where localized surface plasmon resonance (LSPR) scattering is used for tracking solid-state, interfacial, and near-field-driven chemical reactions occurring in individual nanoscale locations. Third, we explore the utility of surface- and tip-enhanced Raman scattering to monitor individual bond-dissociation and bond-formation events occurring locally in chemical reactions on surfaces. Each example has yielded some new understanding about molecular mechanisms or location-to-location heterogeneity in chemical activity. The review finishes with new and complementary tools that are expected to further enhance the scope of knowledge attainable through nanometer-scale resolution chemical imaging.

Difficult Airway of Fetus: Making a Safe Ex Utero Intrapartum Treatment.

Large neck masses involving the airway can lead to hypoxia or the demise of the newborn in case the airway is not secured in time. A planned ex utero intrapartum treatment (EXIT) enables to access the airway by various means under optimal conditions. Advancements in imaging and well-orchestrated teamwork enable to improve the survival by EXIT procedure.

Cystic Nephroma and its Varied Management Scenarios: A Report of two Cases.

Cystic nephroma is a rare benign cystic neoplasm of the kidney. The preoperative diagnosis with its malignant counterparts cystic partially differentiated nephroblastoma or cystic Wilms' tumor is not easy but is important when one is considering for nephron-sparing surgery.

Ex-vivo repair for multiple and intraparenchymal renal artery aneurysms.

A 45-year-old woman with known hypothyroidism and no other comorbidities was incidentally found to have multiple right renal artery aneurysms. The largest aneurysm measured 5 x 4.5 cm and arose from an inferior segmental branch while two smaller aneurysms arose from an upper segmental branch of the right renal artery. We performed an ex-vivo repair with reverse saphenous vein graft under cold preservation followed by orthotopic kidney auto-transplantation. Her postoperative course was unremarkable and at 1-year follow-up her right kidney is preserved. In this article, we report successful treatment of complex multiple right renal artery aneurysms and describe the surgical technique used for successful repair.

Uma mulher de 45 anos com hipotireoidismo conhecido e sem outras comorbidades teve achado incidental de múltiplos aneurismas da artéria renal direita. O maior aneurisma media 5 x 4,5 cm e tinha origem no ramo segmentar inferior, juntamente com dois pequenos aneurismas originários do ramo segmentar superior da artéria renal direita. Realizamos o reparo ex vivo com enxerto reverso de veia safena, sob preservação a frio, seguido de autotransplante renal ortotópico. O pós-operatório ocorreu sem intercorrências, e a paciente teve o rim direito preservado no seguimento de 1 ano. Neste artigo, relatamos o tratamento bem-sucedido de múltiplos aneurismas complexos da artéria renal direita e descrevemos a técnica cirúrgica utilizada para o reparo bem-sucedido.

Receptor-Specific Delivery of Peptide Nucleic Acids Conjugated to Three Sequentially Linked N-Acetyl Galactosamine Moieties into Hepatocytes.

Peptide nucleic acids (PNAs) are DNA analogs that bind with high affinity to DNA and RNA in a sequence-specific manner but have poor cell permeability, limiting use as therapeutic agents. The work described here is motivated by recent reports of efficient gene silencing specifically in hepatocytes by small interfering RNAs conjugated to triantennary N-acetyl galactosamine (GalNAc), the ligand recognized by the asialoglycoprotein receptor (ASGPR). PNAs conjugated to either triantennary GalNAc at the N-terminus (the branched architecture) or monomeric GalNAc moieties anchored at Cγ of three consecutive PNA monomers of N-(2-aminoethyl)glycine (aeg) scaffolds (the sequential architecture) were synthesized on the solid phase. These formed duplexes with complementary DNA and RNA as shown by UV and circular dichroism spectroscopy. The fluorescently labeled analogs of GalNAc-conjugated PNAs were internalized by HepG2 cells that express the ASGPR but were not taken up by HEK-293 cells that lack this receptor. The sequential conjugate was internalized about 13-fold more efficiently than the branched conjugate into HepG2 cells, as demonstrated by confocal microscopy. The results presented here highlight the potential significance of the architecture of GalNAc conjugation for efficient uptake by target liver cells and indicate that GalNAc-conjugated PNAs have possible therapeutic applications.