Study of the influence of tributyrin-supplemented diets on the gut bacterial communities of rainbow trout (Oncorhynchus mykiss)

Dietary supplementation with triglyceride tributyrin (TBT), a butyrate precursor, has been associated with beneficial effects on fish health and improvements in the ability of carnivorous fish to tolerate higher levels of plant-based protein. In this study, we aimed to investigate the effects of a plant-based diet supplemented with TBT on the structural diversity and putative function of the digesta-associated bacterial communities of rainbow trout (Oncorhynchus mykiss). In addition to this, we also assessed the response of fish gut digestive enzyme activities and chyme metabolic profile in response to TBT supplementation. Our results indicated that TBT had no significant effects on the overall fish gut bacterial communities, digestive enzyme activities or metabolic profile when compared with non-supplemented controls. However, a more in-depth analysis into the most abundant taxa showed that diets at the highest TBT concentrations (0.2% and 0.4%) selectively inhibited members of the Enterobacterales order and reduced the relative abundance of a bacterial population related to Klebsiella pneumoniae, a potential fish pathogen. Furthermore, the predicted functional analysis of the bacterial communities indicated that increased levels of TBT were associated with depleted KEGG pathways related to pathogenesis. The specific effects of TBT on gut bacterial communities observed here are intriguing and encourage further studies to investigate the potential of this triglyceride to promote pathogen suppression in the fish gut environment, namely in the context of aquaculture.

Origin of Polarization in Bismuth Sodium Titanate-Based Ceramics

The classical view of the structural changes that occur at the ferroelectric transition in perovskite-structured systems, such as BaTiO3, is that polarization occurs due to the off-center displacement of the B-site cations. Here, we show that in the bismuth sodium titanate (BNT)-based composition 0.2(Ba0.4Sr0.6TiO3)-0.8(Bi0.5Na0.5TiO3), this model does not accurately describe the structural situation. Such BNT-based systems are of interest as lead-free alternatives to currently used materials in a variety of piezo-/ferroelectric applications. A combination of high-resolution powder neutron diffraction, impedance spectroscopy, and ab initio calculations reveals that Ti4+ contributes less than a third in magnitude to the overall polarization and that the displacements of the O2- ions and the A-site cations, particularly Bi3+, are very significant. The detailed examination of the ferroelectric transition in this system offers insights applicable to the understanding of such transitions in other ferroelectric perovskites, particularly those containing lone pair elements.

Interplay between Side Chain Density and Polymer Alignment: Two Competing Strategies for Enhancing the Thermoelectric Performance of P3HT Analogues

A series of polythiophenes with varying side chain density was synthesized, and their electrical and thermoelectric properties were investigated. Aligned and non-aligned thin films of the polymers were characterized in the neutral and chemically doped states. Optical and diffraction measurements revealed an overall lower order in the thin films with lower side chain density, also confirmed using polarized optical experiments on aligned thin films. However, upon doping the non-aligned films, a sixfold increase in electrical conductivity was observed for the polythiophene with the lowest side chain density compared to poly(3-hexylthiophene) (P3HT). We found that the improvement in conductivity was not due to a larger charge carrier density but an increase in charge carrier mobility after doping with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ). On the other hand, doped aligned films did not show the same trend; lower side chain density instead led to a lower conductivity and Seebeck coefficient compared to those for P3HT. This was attributed to the poorer alignment of the polymer thin films with lower side chain density. The study demonstrates that optimizing side chain density is a synthetically simple and effective way to improve electrical conductivity in polythiophene films relevant to thermoelectric applications.

Pyridine Functionalized Carbon Nanotubes: Unveiling the Role of External Pyridinic Nitrogen Sites for Oxygen Reduction Reaction

Pyridinic nitrogen has been recognized as the primary active site in nitrogen-doped carbon electrocatalysts for the oxygen reduction reaction (ORR), which is a critical process in many renewable energy devices. However, the preparation of nitrogen-doped carbon catalysts comprised of exclusively pyridinic nitrogen remains challenging, as well as understanding the precise ORR mechanisms on the catalyst. Herein, a novel process is developed using pyridyne reactive intermediates to functionalize carbon nanotubes (CNTs) exclusively with pyridine rings for ORR electrocatalysis. The relationship between the structure and ORR performance of the prepared materials is studied in combination with density functional theory calculations to probe the ORR mechanism on the catalyst. Pyridinic nitrogen can contribute to a more efficient 4-electron reaction pathway, while high level of pyridyne functionalization result in negative structural effects, such as poor electrical conductivity, reduced surface area, and small pore diameters, that suppressed the ORR performance. This study provides insights into pyridine-doped CNTs-functionalized for the first time via pyridyne intermediates-as applied in the ORR and is expected to serve as valuable inspiration in designing high-performance electrocatalysts for energy applications.

Programmed Self-Assembly of DNA Nanosheets with Discrete Single-Molecule Thickness and Interfacial Mechanics: Design, Simulation, and Characterization

DNA is programmed to hierarchically self-assemble into superstructures spanning from nanometer to micrometer scales. Here, we demonstrate DNA nanosheets assembled out of a rationally designed flexible DNA unit (F-unit), whose shape resembles a Feynman diagram. F-units were designed to self-assemble in two dimensions and to display a high DNA density of hydrophobic moieties. oxDNA simulations confirmed the planarity of the F-unit. DNA nanosheets with a thickness of a single DNA duplex layer and with large coverage (at least 30 μm × 30 μm) were assembled from the liquid phase at the solid/liquid interface, as unambiguously evidenced by atomic force microscopy imaging. Interestingly, single-layer nanodiscs formed in solution at low DNA concentrations. DNA nanosheet superstructures were further assembled at liquid/liquid interfaces, as demonstrated by the fluorescence of a double-stranded DNA intercalator. Moreover, the interfacial mechanical properties of the nanosheet superstructures were measured as a response to temperature changes, demonstrating the control of interfacial shear mechanics based on DNA nanostructure engineering. The rational design of the F-unit, along with the presented results, provide an avenue toward the controlled assembly of reconfigurable/responsive nanosheets and membranes at liquid/liquid interfaces, to be potentially used in the characterization of biomechanical processes and materials transport.

Aqueous processing of organic semiconductors enabled by stable nanoparticles with built-in surfactants

The introduction of oligoether side chains onto a polymer backbone can help to stabilise polymeric dispersions in water without the necessity of surfactants or additives when conjugated polymer nanoparticles are prepared. A series of poly(3-hexylthiophene) (P3HT) derivatives with different content of a polar thiophene derivative 3-((2-methoxyethoxy)methyl)thiophene was interrogated to find the effect of the polar chains on the stability of the formed nanoparticles, as well as their structural, optical, electrochemical, and electrical properties. Findings indicated that incorporation of 10-20 percent of the polar side chain led to particles that are stable over a period of 42 days, with constant particle size and polydispersity, however the particles from the polymer with 30 percent polar side chain showed aggregation effects. The polymer dispersions showed a stronger solid-like behaviour in water with decreasing polar side chain content, while thin film deposition from water was found to afford globular morphologies and crystallites with more isotropic orientation compared to conventional solution-processed films. As a proof-of-principle, field-effect transistors were fabricated directly from the aqueous dispersions demonstrating that polymers with hydrophilic moieties can be processed in water without the requirement of surfactants.

Nanoscale Control of DNA-Linked MoS2-Quantum Dot Heterostructures

The ability to control the assembly of mixed-dimensional heterostructures with nanoscale control is key for the fabrication of novel nanohybrid systems with new functionalities, particularly for optoelectronics applications. Herein we report a strategy to control the assembly of heterostructures and tune their electronic coupling employing DNA as a linker. We functionalized MoS2 nanosheets (NSs) with biotin-terminated dsDNA employing three different chemical strategies, namely, thiol, maleimide, and aryl diazonium. This allowed us to then tether streptavidinated quantum dots (QDs) to the DNA functionalized MoS2 surface via biotin-avidin recognition. Nanoscale control over the separation between QDs and NSs was achieved by varying the number of base pairs (bp) constituting the DNA linker, between 10, 20, and 30 bp, corresponding to separations of 3.4, 6.8, and 13.6 nm, respectively. Spectroscopic data confirmed the successful functionalization, while atomic force and transmission electron microscopy were employed to image the nanohybrids. In solution steady-state and time-resolved photoluminescence demonstrated the electronic coupling between the two nanostructures, that in turn was observed to progressively scale as a function of DNA linker employed and hence distance between the two nanomoieties in the hybrids.

Antiferroelectric-like Behavior in a Lead-Free Perovskite Layered Structure Ceramic

Antiferroelectric (AFE) materials have been intensively studied due to their potential uses in energy storage applications and energy conversion. These materials are characterized by double polarization-electric field (P-E) hysteresis loops and nonpolar crystal structures. Unusually, in the present work, Sr_1.68La_0.32Ta_1.68Ti_0.32O₇ (STLT32), Sr_1.64La_0.36Ta_1.64Ti_0.36O₇ (STLT36), and Sr_1.85Ca_0.15Ta₂O₇ (SCT15), lead-free perovskite layered structure (PLS) materials, are shown to exhibit AFE-like double P-E hysteresis loops despite maintaining a polar crystal structure. The double hysteresis loops are present over wide ranges of electric field and temperature. While neutron diffraction and piezoresponse force microscopy results indicate that the STLT32 system should be ferroelectric at room temperature, the observed AFE-like electrical behavior suggests that the electrical response is dominated by a weakly polar phase with a field-induced transition to a more strongly polar phase. Variable-temperature dielectric measurements suggest the presence of two-phase transitions in STLT32 at ca. 250 and 750 °C. The latter transition is confirmed by thermal analysis and is accompanied by structural changes in the layers, such as in the degree of octahedral tilting and changes in the perovskite block width and interlayer gap, associated with a change from non-centrosymmetric to centrosymmetric structures. The lower-temperature transition is more diffuse in nature but is evidenced by subtle changes in the lattice parameters. The dielectric properties of an STLT32 ceramic at microwave frequencies was measured using a coplanar waveguide transmission line and revealed stable permittivity from 1 kHz up to 20 GHz with low dielectric loss. This work represents the first observation of its kind in a PLS-type material.

Fabrication and Functionalisation of Nanocarbon-Based Field-Effect Transistor Biosensors

Nanocarbon-based field-effect transistor (NC-FET) biosensors are at the forefront of future diagnostic technology. By integrating biological molecules with electrically conducting carbon-based platforms, high sensitivity real-time multiplexed sensing is possible. Combined with their small footprint, portability, ease of use, and label-free sensing mechanisms, NC-FETs are prime candidates for the rapidly expanding areas of point-of-care testing, environmental monitoring and biosensing as a whole. In this review we provide an overview of the basic operational mechanisms behind NC-FETs, synthesis and fabrication of FET devices, and developments in functionalisation strategies for biosensing applications.

Regulation of cardiomyocyte adhesion and mechanosignalling through distinct nanoscale behaviour of integrin ligands mimicking healthy or fibrotic extracellular matrix

The stiffness of the cardiovascular environment changes during ageing and in disease and contributes to disease incidence and progression. Changing collagen expression and cross-linking regulate the rigidity of the cardiac extracellular matrix (ECM). Additionally, basal lamina glycoproteins, especially laminin and fibronectin regulate cardiomyocyte adhesion formation, mechanics and mechanosignalling. Laminin is abundant in the healthy heart, but fibronectin is increasingly expressed in the fibrotic heart. ECM receptors are co-regulated with the changing ECM. Owing to differences in integrin dynamics, clustering and downstream adhesion formation this is expected to ultimately influence cardiomyocyte mechanosignalling; however, details remain elusive. Here, we sought to investigate how different cardiomyocyte integrin/ligand combinations affect adhesion formation, traction forces and mechanosignalling, using a combination of uniformly coated surfaces with defined stiffness, polydimethylsiloxane nanopillars, micropatterning and specifically designed bionanoarrays for precise ligand presentation. Thereby we found that the adhesion nanoscale organization, signalling and traction force generation of neonatal rat cardiomyocytes (which express both laminin and fibronectin binding integrins) are strongly dependent on the integrin/ligand combination. Together our data indicate that the presence of fibronectin in combination with the enhanced stiffness in fibrotic areas will strongly impact on the cardiomyocyte behaviour and influence disease progression. This article is part of the theme issue 'The cardiomyocyte: new revelations on the interplay between architecture and function in growth, health, and disease'.

Myocardial work impairment in children with Wolff-Parkinson-White syndrome

Background

Wolf-Parkinson-White Syndrome (WPW) has been associated with reduced local myocardium deformation during systole. According to guidelines, when the left ventricle (LV) dysfunction is present catheter ablation of the accessory pathway may be required, even in asymptomatic patients.

Purpose

The study aimed to assess the diagnostic value of non-invasive myocardial work in predicting subtle myocardial abnormalities in children with WPW.

Methods

Eighty pediatric patients (age 7.91±3.2 years) were included in the study: 20 cases with manifest WPW and 60 age- and sex-matched controls (CTR). Global myocardial work index (MWI) was measured as the area of the LV pressure-strain loops. From MWI, global Constructive Work (MCW), Wasted Work (MWW) and Work Efficiency (MWE) were estimated. In addition, standard echocardiographic parameters of LV function were evaluated.

Results

Patients characteristics are summarized in the table. Despite normal LV EF and GLS, children with WPW had worse MWI (WPW 1292.90±307.67 mmHg% vs CTR 1658.73±241.74 mmHg%, p=0.0000005), MCW (WPW 1844.15±267.96 mmHg% vs CTR 2104.90±237.85 mmHg%, p=0.00009), MWW (WPW 101.5 [85–148.25] mmHg% vs CTR 72 [54.75–109.25] mmHg%, p=0.004) and GWE (WPW 94 [91.75–95] mmHg% vs 96 [95–97] mmHg%, p=0.00012) (table). In the WPW group, MWE (r=−0.6, p=0.009) and MWW (r=0.6, p=0.01) was found to correlate with a prolonged QRS (figure).

A multiple regression model was generated to identify the relation between abnormal myocardial work indices (worst interquartile range as dependent variable) and several independent variables. QRS was the best independent predictor of impaired myocardial work. In particular, a QRS>110 msec showed an 86% sensibility and 85% specificity for abnormal MWE (AUC of 0.85), and a 75% sensibility and 83% specificity for abnormal MWW (AUC of 0.83) (figure).

Conclusion

In children with WPW, myocardial work indices were found significantly reduced, even in presence of normal LV EF and GLS. Prolonged QRS independently predicted myocardial impairment. In pediatric patients with WPW, myocardial work may represent a sensitive measure of LV dysfunction and help in the decision-making.

Funding Acknowledgement

Type of funding sources: None.

COVID-19 vaccination in adults with congenital heart disease: results of 1-year prospective study

Background

Adults with congenital heart disease (ACHD) are a vulnerable population. Routine vaccination is the only strategy to prevent a life-threatening infection. However, concerns on the cardiac safety and efficacy of COVID-19 vaccines have been raised.

Aim

To assess safety and efficacy of available COVID-19 vaccines in ACHD patients.

Methods

Data on COVID-19 infection and vaccines including booster doses and any suspected or confirmed adverse events were prospectively collected for all ACHD patients attending our tertiary centre from the beginning of the vaccination campaign (March 2021). A group of 75 healthy volunteers, matched per age and sex, was included for comparison. Antispike IgG titre was routinely obtained at the ACHD clinic. Patients' attitude towards COVID-19 was explored with a questionnaire.

Results

As of February 2022, 498 ACHD patients (36.7±16 years, 54% male,69% with moderate-complex defects, 48% with advanced physiological stage) were enrolled. Four hundred and sixty-one (92%) were fully vaccinated: the type of vaccine was Pfizer-BioNTech for 399 (86%) patients, Moderna for 20 (4%) and AstraZeneca for 26 (6%), 9 received a mixed vaccine regimen (2%). Forty-two (9%) had a history of previous COVID-19 infection and therefore received only one dose. Two-hundred and sixty-nine (58%) patients received a booster dose. Adverse events were mainly mild and transient. One patient complaining of chest pain following administration of mRNA-based vaccination was diagnosed with acute pericarditis, which made full remission after appropriate therapy. Two patients reported a non-specific increment of inflammatory markers. No other severe adverse events were reported. Thirty-seven (7%) refused COVID-19 vaccination being scared of potential cardiac/extra-cardiac adverse events. Among those not-vaccinated, 9 (24%) had a history of previous mild COVID-19 infection. IgG titre was measured in 243 patients at 1915 [835–5934] BAU/ml, which was significantly higher compared to controls (1196 [827–2048] BAU/ml, p=0.002). Three ACHD patients contracted COVID-19 infection after the first dose, while 65 (14%) fully vaccinated patients tested positive for COVID-19, all with mild to moderate symptoms. COVID-19 symptoms duration was significantly longer in case of infection before vaccination (10 [2.7–15] vs 3 [1.2–7], p=0.03). One Fontan patient was tested positive for COVID-19 twice, before and after COVID-19 vaccination, requiring hospitalization in both cases. Four hundred and seven patients completed the questionnaire: 128 (31%) declared to be scared of potential cardiac effects of the vaccine and that the discussion with the ACHD cardiologist was crucial to decide to undergo COVID-19 vaccination.

Conclusions

Our data provide real-world evidence on COVID-19 vaccines safety and efficacy in ACHD patients. Patients' education from the ACHD team may play a key role in vaccine acceptance in this vulnerable population.

Funding Acknowledgement

Type of funding sources: None.

Effects of sacubitril/valsartan in patients with a systemic right ventricle

Background

Sacubitril/valsartan has been proved to reduce mortality in heart failure and reduced ejection fraction (EF) and is currently recommended as first-line therapy. However, effects in patients with a systemic right ventricle (sRV) have not been systematically investigated yet.

Purpose

We aimed to assess safety and efficacy of sacubitril/valsartan in patients with a sRV

Methods

From September 2020 to April 2021, all patients with congenitally corrected transposition of the great arteries (TGA) or TGA after Senning/Mustard repair attending our tertiary centre were prospectively enrolled. Inclusion criteria were: age ≥18 years, 3-months of optimal medical therapy including ACEi/ARB and sRV EF≤40%. Patients with univentricular physiology, systolic blood pressure (SBP) <90 mmHg, glomerular filtration rate (GFR) <30 ml/min or K >5.5 mEq/L were excluded. SBP and blood samples were obtained at 1-month of treatment. Other clinical and echocardiographic variables were reassessed at 6 and 12-month follow-up and the medication was progressively up-titrated to the highest tolerated dose.

Results

Fifty-one patients (38±11 years, 60% male, 34% ccTGA) were included. Up to March 2022, 48 (92%) patients were reviewed after 6 months of therapy and 35 (68%) completed the first year of follow-up. Baseline patients' characteristics are summarized in Table 1. At 1 month, treatment did not impact on the serum potassium values (4.5±0.3 vs 4.4±0.3 mEq/L, p=0.9) and GFR (112±33 vs 112±31 ml/min, p=0.3), while SBP dropped significantly (119±13 vs 108±18 mmHg, p=0.003). Two patients ceased the treatment due to symptomatic hypotension during the first month. One patient developed a nephrotic syndrome at 4 months of follow-up, which was likely unrelated to the treatment. No other major adverse events were reported. One patient was lost to follow-up after 3 months. Despite no significant change in the NYHA class (p=0.9), the 6-minute walking distance increased significantly at 6-month (Table 2). Nt pro BNP values were significantly decreased at 6-month, and returned to baseline at 12-month. Improved sRV systolic function was demonstrated at 6 and 12-month by significant increase in fractional area change, RV global longitudinal strain and sRV EF measured with 3D echocardiography.

Conclusions

Our mid-term results showed that sacubitril/valsartan is well tolerated in patients with a sRV and leads to signficant improvement of sRV systolic function, supporting its use in this complex population.

Funding Acknowledgement

Type of funding sources: None.

Single molecule DNA origami nanoarrays with controlled protein orientation

The nanoscale organization of functional (bio)molecules on solid substrates with nanoscale spatial resolution and single-molecule control-in both position and orientation-is of great interest for the development of next-generation (bio)molecular devices and assays. Herein, we report the fabrication of nanoarrays of individual proteins (and dyes) via the selective organization of DNA origami on nanopatterned surfaces and with controlled protein orientation. Nanoapertures in metal-coated glass substrates were patterned using focused ion beam lithography; 88% of the nanoapertures allowed immobilization of functionalized DNA origami structures. Photobleaching experiments of dye-functionalized DNA nanostructures indicated that 85% of the nanoapertures contain a single origami unit, with only 3% exhibiting double occupancy. Using a reprogrammed genetic code to engineer into a protein new chemistry to allow residue-specific linkage to an addressable ssDNA unit, we assembled orientation-controlled proteins functionalized to DNA origami structures; these were then organized in the arrays and exhibited single molecule traces. This strategy is of general applicability for the investigation of biomolecular events with single-molecule resolution in defined nanoarrays configurations and with orientational control of the (bio)molecule of interest.

Blood flow vortices adapt their behaviour to the presence of kent accessory pathway

Funding Acknowledgements

Type of funding sources: None.

Background

Blood speckle imaging (BSI) is a new speckle-tracking-based technique for the evaluation of blood flow. Ventricular flow vortices have been studied in sinus rhythm in normal and dysfunctional hearts, however, data are lacking in patients with Kent accessory pathway (KAP) and short atrio-ventricular (AV) conduction.

Purpose

We aimed to evaluate the characteristics of left ventricle blood vortices in children with KAP.

Methods

Nineteen paediatric patients (age 7 ± 2.9 years) were included in the study: 13 patients with manifest KAP (KAP group) and 6 age and sex -matched controls with normal AV conduction (CTR group). A thorough echocardiographic evaluation with 2D, color doppler and BSI was performed in all the included patients. BSI was recorded in apical 3-chamber view with a 6S-D probe. Vortices characteristic were analysed during filling phase of the left ventricle. We focused on the anterior vortex generated by mitral valve, which persisted longer during the cardiac cycle and is assumed to contribute to optimizing cardiac function. A standard 12-lead ECG was also recorded for each child in KAP group to esteem KAP localization.

Results

According to Arruda criteria for KAP localization, all patients in KAP group manifested the accessory pathway in the septal region. All patients in CTR group presented one major anterior vortex during filling phase, while in KAP group 10 patients out of 13 (p= 0.009) lacked of this main anterior vortex, showing instead fragmented different vortices. There were no differences in term of left ventricle function (KAPg 59.8 ± 4.02% vs CTRg 59.0 ± 2.5%, p= 0.6) and global longitudinal strain (KAPg -18.6 ± 1.0% vs CTRg -19.6 ± 3.1%, p= 0.5) between the two groups.

Conclusion

In our preliminary analysis, in patients with septal KAP, blood vortices adapted their diastolic traces to the septal dyssynchrony showing a fragmented pattern. We speculate this fragmentation may contribute to impair the performance of the left ventricle. Abstract Figure. BSI in control vs patient with WPW

Myocardial work indices and ventricular dyssynchrony in adults with aortic coarctation

Funding Acknowledgements

Type of funding sources: None.

Background

Adults with coarctation of the aorta (CoA) may present residual aortic obstruction and develop arterial vasculopathy and subclinical left ventricular (LV) dysfunction. Myocardial work (MW) is a novel non-invasive index of myocardial efficiency calculated from echocardiographic LV pressure-strain loops, which yields incremental information over ejection fraction and global longitudinal strain. (GLS)

Purpose

Aim of the present study is to analyze LVMW in a cohort of adult patients with operated aortic CoA

Methods

CoA patients aged > 18 years who underwent transthoracic echocardiography between September 2020 and July 2021 at our tertiary centre were included. Exclusion criteria were significant recoarctation, impaired LVEF, significant valvular disease and suboptimal image quality. A group of healthy individuals with no cardiac abnormalities. GLS and peak strain dispersion(PSD) were measured. MW indices were calculated using the blood pressure measured in the right arm at the time of the exam.

Results

Sixty patients (26[22-33]years, 66%male) were included. Data on previous medical history, clinical status at last assessment and Coa-related echocardiographic findings are showed in table 1. No significant differences in traditional parameters of LV systolic and diastolic function were found between groups (EF 60[57-64] vs 57[53-61],p = 0.6), however Coa patients had higher LVmass (84[75-97] vs 68[56-75]g). GLS and MW indices in the study population and in the control group  are reported in table 2. Coa group showed lower GLS values and higher PSD (p < 0.0001 for both). Global work index(GWI) and global constructive work(GCW) values were not significantly different between groups, whereas CoA group showed significant increase of global wasted work(GWW) and impaired global work efficiency(GWE,p = 0.003 and 0.0005 respectively). Spearman’s linear method illustrated that both GCW and GWI had a moderate positive relation with mean gradient across the descending aorta at continuous wave Doppler. PSD was positively related to GWW and inversely related to GWE(Figure 1). Using linear regression model with the log of GWE values as dependent variable,PSD,age(β:-0.002,p = 0.03) and LVmass(β:-0.06,p = 0.004)were related to GWE. However, only PSD retained a significant relation on multivariable analysis(β:-0.002,p > 0.0001).

Conclusion

MW indices assessment is feasible in Coa patients may provide a more comprehensive understanding of the overall myocardial mechanics and performance. In particular, MW demonstrated impaired LV efficiency, which was strongly related to increased mechanical dispersion in Coa patients. Abstract Figure.  Abstract Figure.

Impaired myocardial work in paediatric patients with wolff-parkinson-white syndrome

Funding Acknowledgements

Type of funding sources: None.

Background

Wolff-Parkinson-White Syndrome (WPW) has been associated with reduced local myocardium deformation during systole. Left ventricle (LV) dysfunction due to electrical dyssynchrony may require catheter ablation of the accessory pathway, even in asymptomatic patients.

Purpose

The study aimed to assess the diagnostic value of non-invasive myocardial work in predicting subtle myocardial abnormalities in patients with WPW.

Methods

Forty-four paediatric patients (age 8.2 ± 4.3 years) were included in the study: 12 cases with manifest WPW and 32 age-, sex- and arterial pressure- matched controls (CTR). LV ejection fraction (EF) and global longitudinal strain (GLS) were evaluated. Global myocardial work index (MWI) was measured as the area of the LV pressure-strain loops. From MWI, global Constructive Work (MCW), Wasted Work (MWW) and Work Efficiency (MWE) were estimated.

Results

Despite normal LV systolic function by standard echocardiographic parameters, patients with WPW had lower MWI (1233.5 ± 281.6 mmHg% in WPW vs 1624.0 ± 305.8 mmHg% in CTR, p = 0.0004), MCW (1833.4 ± 257.9 mmHg% in WPW vs 2069.0 ± 319.9 mmHg% in CTR, p= 0.03), MWW (187.6 ± 117.7 mmHg% in WPW vs 90.9 ± 58.9 mmHg% in CTR, p= 0.0008) and GWE (90.5 ± 4.8% in WPW vs 95.2 ± 2.2% in CTR, p= 0.00006). There were no significant differences in GLS and EF between patients with WPW and controls.

Conclusion

Myocardial work indices were found significantly reduced in patients with WPW, even in presence of normal LV EF and GLS. In patients with WPW, MWI may represent a sensitive measure of myocardial dysfunction and help in the decision-making for catheter ablation. Abstract Figure. Myocardial work in WPW  Abstract Figure. Myocardial work in control patient

Engineering a DNA origami mediated multicolour quantum dot platform for sub-diffraction spectral separation imaging

The validation of super-resolution optical imaging techniques requires well-defined reference samples that can be used repeatedly and reliably as model standards. Here, we engineer a DNA origami scaffold-mediated multicolour quantum dot hybrid nanostructure and test it using a recently proposed Quantum Dot-based spectral separation technique. We show that multivalent DNA structures offer a robust and precise nanoscale quantum dot placement scaffold, while the spectral resolution method provides relatively simple and fast image acquisition capabilities using any standard confocal or fluorescence microscope capable of spectral signal separation and a single excitation laser wavelength.

The validation of super-resolution optical imaging techniques requires well-defined reference samples that can be used repeatedly and reliably as model standards.

Grain Size Effects in Mn-Modified 0.67BiFeO3-0.33BaTiO3 Ceramics

Grain size can have significant effects on the properties of electroceramics for dielectric, piezoelectric, and ferroelectric applications. Here, we systematically investigate the effect of grain size on the structure and properties of Mn-modified 0.67BiFeO₃-0.33BaTiO₃ ceramics, an important lead-free piezoelectric ceramic that exhibits both a high piezoelectric coefficient and a high Curie point. Ceramics with average grain sizes ranging from 0.46 to 6.85 μm were prepared using conventional and spark plasma sintering. It was found that the morphotropic phase boundary compositions are composed of two polar structures, rhombohedral and tetragonal, with DC poling inducing an increase in the fraction of the rhombohedral phase. All ceramics show relaxor behavior and their freezing temperature moves to higher temperatures with increasing grain size, although their Burns temperature is independent of grain size. In fine-grained ceramics, which show pronounced relaxor behavior, significant grain size dependency is seen in dielectric, piezoelectric, and ferroelectric properties, which is attributed to the presence of single ferroelectric domains and high concentrations of polar nanoregions. In coarse-grained ceramics, a critical grain size of 2.83 μm yields the highest dielectric permittivity at room temperature, with the piezoelectric coefficient plateauing at this grain size, which can be attributed to the contribution of both polar nanoregions and high domain wall density.

Effects of sacubitril/valsartan in patients with a systemic right ventricle: early evidence of exercise tolerance and systolic function improvement

Background

Sacubitril/valsartan has been shown to reduce mortality and morbidity inpatients with heart failure and reduced systolic function. However, the effects of this novel association in patients with congenital heart disease and a systemic right ventricle (sRV) have not been investigated yet.

Purpose

We aimed to assess tolerability and efficacy of sacubitril/valsartan in patients with a sRV

Methods

From September 2020 to March 2021, 38 patients with congenitally corrected transposition of the great arteries or transposition of the great arteries after Senning or Mustard repair were prospectively enrolled. Inclusion criteria were: age ≥18 years, optimal medical therapy including ACEi/ARB for at least 6 months and EF of the sRV ≤40%. Patients with univentricular physiology, systolic blood pressure (SBP) <90mmHg, glomerular filtration rate (GFR) <30ml/min or K >5.5mEq/L were excluded. RV systolic function was assessed on echocardiography using a multiparametric evaluation. The study protocol contemplates serial assessments at 1, 3, 6 and 12 months after treatment initiation.

Results

Up to March 31th, 23 patients completed 1-month and 15 completed 3-month assessment after treatment initiation. Baseline patients' characteristics are summarized in table 1. The medication dose was up-titrated to the highest tolerated dose during follow-up. During early follow-up, no major adverse events were reported. Treatment did not impact significantly on the values of serum potassium (basal K+ 4.4 [4.2–4.6] mEq/L, K+ at 3 months 4.4 [4.3–4.6] mEq/L, p=0.7) and GFR (basal GFR 113.9±35ml/min, GFR at 3 months 107.8±21 ml/min, p=0.7). Although SBP did not change significantly (114±12 vs 113.9±19 mmHg at 1-month and 117.3±12 mmHg at 3 months; p=0.9 for both), 2 (5%) patients ceased the treatment due to symptomatic hypotension during the first month of treatment. There was no significant change in the NYHA class. However, the 6-minute walking distance increased significantly after 3 months (365±120 vs 498.3±71 min; p=0.01). Furthermore, while traditional echocardiographic parameters of RV systolic function (TAPSE, s wave and FAC) did not change significantly, RV global longitudinal strain (GLS) and RV free wall GLS demonstrated subclinical improvement in right ventricular systolic function (table 2).

Conclusions

Our short-term results from an ongoing prospective study showed that sacubitril/valsartan is well tolerated in patients with a sRV with early evidence of improvement in exercise tolerance and sRV systolic function. Longer follow-up is warranted to confirm these data.

Funding Acknowledgement

Type of funding sources: None. Table 1Table 2

Prognostic relevance of thyroid disease in adults with congenital heart disease

Background

Adults with congenital heart disease (ACHD) are frequently affected by thyroid diseases (TD). However, the clinical relevance of TD in ACHD remains unknown.

Purpose

We aimed to describe the prevalence of TD in the ACHD population and to ascertain whether TD are associated with worse outcome.

Methods

Clinical data on all consecutive patients aged >18 years attending our ACHD unit for a day-case between 2014 and 2019 were retrospectively collected. For statistical analysis, a composite endpoint was created combining the following events at follow-up: hospitalization for heart failure, new-onset tachyarrhythmic or bradyarrhythmic events and death.

Results

Four hundred ninety-five ACHD patients with a median age of 32.2 [24.5–45.6] years (46% male) were included. There was an overall prevalence of patients with moderate or complex lesions (414=84%). Compared to the group with no history of TD, patients in the TD were older, (41.9 [29.7–53.5] vs 30.2 [24.3–39] years; p<0.0001) and mainly female (77% vs 46%; p<0.0001) and more likely to have undergone at least two cardiac catheterization procedures (29 vs 13%; p<0.0001). Genetic disorders including Down syndrome were more prevalent in the group with TD (p<0.0001). Moreover, at last follow-up, those with TD had higher pro-BNP-nt values (243.5 [96.5–523] pg/ml Vs 94 [45–207] pg/ml; p<0.0001) and were in a more advanced NYHA class (27% vs 13% in class III-IV; p=0.0002). Echocardiography showed lower EF in the TD group (55 [55–60]% vs 60 [55–65]%; p=0.0002).

Median follow-up was 9.4 [4.5–13.1] years. Patients with TD had a higher unadjusted mortality rate, with a trend towards statistical significance (p=0.07). Sixty-four (42%) patients in the TD group and 43 (12.5%) met our composite endpoint, leading to a 10-year survival free from events of 53.7% Vs 86.5%, respectively (p<0.0001, Figure1). Multivariate analysis showed that age, ejection fraction, previous surgical palliation, advanced physiological stage and TD were independent predictors of our composite endpoint, even after stratification for genetic disorders as reported in table1. After adjustment for baseline differences between groups with propensity matching score using age, sex, disease complexity, physiological stage, previous palliative or reparative surgery, normal or reduced systemic ventricle ejection fraction, pulmonary arterial hypertension, cyanosis and presence of systemic right ventricle as independent variables, TD remained a strong predictor of cardiac events at follow-up with an hazard ratio of 4.47 (95% CI 2.42–8.28; p<0.0001).

Conclusion

TD is a strong predictor of adverse outcome in the ACHD population after exclusion of potential confounding factors, being related to a fourfold increased risk of events at follow-up.

Funding Acknowledgement

Type of funding sources: None. Figure 1Table 1

A Self-Powered Piezo-Bioelectric Device Regulates Tendon Repair-Associated Signaling Pathways through Modulation of Mechanosensitive Ion Channels

Tendon disease constitutes an unmet clinical need and remains a critical challenge in the field of orthopaedic surgery. Innovative solutions are required to overcome the limitations of current tendon grafting approaches, and bioelectronic therapies show promise in treating musculoskeletal diseases, accelerating functional recovery through the activation of tissue regeneration-specific signaling pathways. Self-powered bioelectronic devices, particularly piezoelectric materials, represent a paradigm shift in biomedicine, negating the need for battery or external powering and complementing existing mechanotherapy to accelerate the repair processes. Here, the dynamic response of tendon cells to a piezoelectric collagen-analogue scaffold comprised of aligned nanoscale fibers made of the ferroelectric material poly(vinylidene fluoride-co-trifluoroethylene) is shown. It is demonstrated that motion-powered electromechanical stimulation of tendon tissue through piezo-bioelectric device results in ion channel modulation in vitro and regulates specific tissue regeneration signaling pathways. Finally, the potential of the piezo-bioelectronic device in modulating the progression of tendinopathy-associated processes in vivo, using a rat Achilles acute injury model is shown. This study indicates that electromechanical stimulation regulates mechanosensitive ion channel sensitivity and promotes tendon-specific over non-tenogenic tissue repair processes.

Tuning Electrostatic Gating of Semiconducting Carbon Nanotubes by Controlling Protein Orientation in Biosensing Devices

The ability to detect proteins through gating conductance by their unique surface electrostatic signature holds great potential for improving biosensing sensitivity and precision. Two challenges are: (1) defining the electrostatic surface of the incoming ligand protein presented to the conductive surface; (2) bridging the Debye gap to generate a measurable response. Herein, we report the construction of nanoscale protein-based sensing devices designed to present proteins in defined orientations; this allowed us to control the local electrostatic surface presented within the Debye length, and thus modulate the conductance gating effect upon binding incoming protein targets. Using a β-lactamase binding protein (BLIP2) as the capture protein attached to carbon nanotube field effect transistors in different defined orientations. Device conductance had influence on binding TEM-1, an important β-lactamase involved in antimicrobial resistance (AMR). Conductance increased or decreased depending on TEM-1 presenting either negative or positive local charge patches, demonstrating that local electrostatic properties, as opposed to protein net charge, act as the key driving force for electrostatic gating. This, in turn can, improve our ability to tune the gating of electrical biosensors toward optimized detection, including for AMR as outlined herein.

Tuning Electrostatic Gating of Semiconducting Carbon Nanotubes by Controlling Protein Orientation in Biosensing Devices

The ability to detect proteins through gating conductance by their unique surface electrostatic signature holds great potential for improving biosensing sensitivity and precision. Two challenges are: (1) defining the electrostatic surface of the incoming ligand protein presented to the conductive surface; (2) bridging the Debye gap to generate a measurable response. Herein, we report the construction of nanoscale protein-based sensing devices designed to present proteins in defined orientations; this allowed us to control the local electrostatic surface presented within the Debye length, and thus modulate the conductance gating effect upon binding incoming protein targets. Using a β-lactamase binding protein (BLIP2) as the capture protein attached to carbon nanotube field effect transistors in different defined orientations. Device conductance had influence on binding TEM-1, an important β-lactamase involved in antimicrobial resistance (AMR). Conductance increased or decreased depending on TEM-1 presenting either negative or positive local charge patches, demonstrating that local electrostatic properties, as opposed to protein net charge, act as the key driving force for electrostatic gating. This, in turn can, improve our ability to tune the gating of electrical biosensors toward optimized detection, including for AMR as outlined herein.

Single-molecule DNA origami aptasensors for real-time biomarker detection

Here we report the use of DNA nanostructures as platforms to monitor the inherent conformational changes of aptamers upon analyte binding, with single-molecule resolution and real-time capability. An aptasensor designed to sense cortisol was found to suffer from instability in solution, but this was reconciled via a rational design of a single-molecule sensing platform. In this regard, DNA origami was employed to immobilise individual aptasensors on a glass surface and to ensure adequate interaction with their environment, for single-molecule analysis. The strategy presented here can be applied to any aptamer obtained by the destabilisation of a duplex in a SELEX process, and hence employed in the rational design of single-molecule biosensors.

DNA-driven dynamic assembly of MoS2 nanosheets

Controlling the assembly of molybdenum disulfide (MoS₂) layers into static and dynamic superstructures can impact on their use in optoelectronics, energy, and drug delivery. Toward this goal, we present a strategy to drive the assembly of MoS₂ layers via the hybridization of complementary DNA linkers. By functionalizing the MoS₂ surface with thiolated DNA, MoS₂ nanosheets were assembled into mulitlayered superstructures, and the complementary DNA strands were used as linkers. A disassembly process was triggered by the formation of an intramolecular i-motif structure at a cystosine-rich sequence in the DNA linker at acidic pH values. We tested the versatility of our approach by driving the disassembly of the MoS₂ superstructures through a different DNA-based mechanism, namely strand displacement. This study demonstrates how DNA can be employed to drive the static and dynamic assembly of MoS₂ nanosheets in aqueous solution.

Effect of glycerol feed-supplementation on seabass metabolism and gut microbiota

Dietary glycerol supplementation in aquaculture feed is seen as an alternative and inexpensive way to fuel fish metabolism, attenuate metabolic utilization of dietary proteins and, subsequently, reduce nitrogen excretion. In this study, we evaluated the impact of dietary glycerol supplementation on nitrogen excretion of European seabass (Dicentrarchus labrax) and its effects on metabolite profile and bacterial community composition of gut digesta. These effects were evaluated in a 60-day trial with fish fed diets supplemented with 2.5% or 5% (w/w) refined glycerol and without glycerol supplementation. Nuclear magnetic resonance spectroscopy and high-throughput 16S rRNA gene sequencing were used to characterize the effects of glycerol supplementation on digesta metabolite and bacterial community composition of 6-h postprandial fish. Our results showed that ammonia excretion was not altered by dietary glycerol supplementation, and the highest glycerol dosage was associated with significant increases in amino acids and a decrease of ergogenic creatine in digesta metabolome. Concomitantly, significant decreases in putative amino acid degradation pathways were detected in the predicted metagenome analysis, suggesting a metabolic shift. Taxon-specific analysis revealed significant increases in abundance of some specific genera (e.g., Burkholderia and Vibrio) and bacterial diversity. Overall, our results indicate glycerol supplementation may decrease amino acid catabolism without adversely affecting fish gut bacterial communities.Key points• Glycerol can be an inexpensive and energetic alternative in fish feed formulations.• Glycerol did not affect nitrogen excretion and gut bacteriome composition.• Glycerol reduced uptake of amino acids and increased uptake of ergogenic creatine.• Glycerol reduced putative amino acid degradation pathways in predicted metagenome.

Probing the nanoscale organisation and multivalency of cell surface receptors: DNA origami nanoarrays for cellular studies with single-molecule control

Nanoscale organisation of receptor ligands has become an important approach to study the clustering behaviour of cell-surface receptors. Biomimetic substrates fabricated via different nanopatterning strategies have so far been applied to investigate specific integrins and cell types, but without multivalent control. Here we use DNA origami to surpass the limits of current approaches and fabricate nanoarrays to study different cell adhesion processes, with nanoscale spatial resolution and single-molecule control. Notably, DNA nanostructures enable the display of receptor ligands in a highly customisable manner, with modifiable parameters including ligand number, ligand spacing and most importantly, multivalency. To test the adaptability and robustness of the system we combined it with focused ion beam and electron-beam lithography nanopatterning to additionally control the distance between the origami structures (i.e. receptor clusters). Moreover, we demonstrate how the platform can be used to interrogate two different biological questions: (1) the cooperative effect of integrin and growth factor receptor in cancer cell spreading, and (2) the role of integrin clustering in cardiomyocyte adhesion and maturation. Thereby we find previously unknown clustering behaviour of different integrins, further outlining the importance for such customisable platforms for future investigations of specific receptor organisation at the nanoscale.

1107 An unusual vegetation on a prosthetic pulmonary valve

Conclusion

Differential diagnosis of cardiac vegetations is a challenging process including microbological tests, multi modality imaging and clinical reasoning. It is always necessary to consider alternative diagnosis, even when traditional imaging tests seem to suggest infective endocarditis.

Non infective thrombotic endocarditis are a rare form of negative blood culteres endocarditis related to systemic hypercoagulable state (i.e. antiphospholipid syndrome, systemic lupus, behcet syndrome, cancer). Malignancies can be considered an unusual cause of cardiac vegetation and they must be taken into account on differential diagnosis.

Abstract 1107 Figure. FDG uptake in pulmonary position

P781 Role of serum biomarkers combined with two-dimensional speckle tracking echocardiography for screening of immunotherapy-induced cardiotoxicity

Background

Immune checkpoint inhibitors (ICIs) are a novel class of antineoplastic drugs which have dramatically changed the management of non-small cell lung cancer. ICI-associated cardiotoxicity is rare, but potentially fatal, presenting in most of cases as autoimmune acute myocarditis during the first phase of treatment. However, since an extensive cardiac monitoring is not routinely performed in most immunotherapy trials, the true incidence of ICIs related cardiac effects is largely unknown.

Aim

Aim of our study is to ascertain a possible subclinical cardiac involvement in patients with non-small cell lung cancer treated with ICIs.

Methods

We prospectively recruited 40 patients (13 males; mean age 64.3 ± 8.3 years) starting immunotherapy with PD-1/PDL-1 inhibitors for non-small lung cancer between January and August 2018. Demographic and clinical data were recorded and all patients underwent a standard 12-lead ECG and a transthoracic echocardiogram with assessment of left ventricular global longitudinal strain (LV GLS). Furthermore, blood samples for pro BNP-nt and high sensitivity Troponin T (hsTnT) measurements were collected. Serial assessments were performed before and 1 and 3 months after initiation of immunotherapy.

Results

A history of previous coronary artery disease was documented in eight cases (20%). At follow-up no cardiovascular events were recorded. Compared with baseline, echocardiographic parameters of ventricular function did not significantly changed at 1 and 3 months (LVEF 61 ± 6% at baseline, 61 ± 5% at 1 month, 60,2 ± 5% at 3 months, p =0.1; E/E’at baseline 9.2 ± 3, 9.2 ± 2.8 at 1 month, 9.1 ±3,5 at 3 months, p = 0.2;TAPSE 20 ± 3.4 mm at baseline, 21.3 ± 2.8 mm at 1 month, 20 ± 3.8 mm at 3 months, p =0.1; LV GLS -20.3 ± 3.6% at baseline, -20.8 ± 2.3% at 1 month, -20.6 ± 3% at 3 months; p = 0.4). Analogously, no significant increase in circulating levels of cardiac biomarkers was found with hsTnT <0.015 ng/ml in all patients at baseline, 1 month and 3 months and median proBNP-nt 118 pg/ml (IQR 47-200) at baseline, 171 pg/ml (IQR 91-520) at 1 month, and 182 pg/ml (IQR 78-470) at 3 months, p = 0.9.

Conclusions

In our study no significant clinical or subclinical evidence of myocardial involvement was detected during treatment with ICIs in patients with non-small cell lung cancer, thus suggesting the potential cardiovascular safety of this promising class of antineoplastic drugs.

Aflatoxin contamination in nuts marketed in Italy: preliminary results

BACKGROUND

Aflatoxins (AFs) are one of the main groups of mycotoxins produced by molds. Nuts, although recognized as a food with health benefits, are frequently contaminated by AFs.

STUDY DESIGN

In this preliminary study we evaluated the contamination by total AFs and AFB1 in different types of nuts from different countries marketed in Apulia.

METHODS

Overall, 124 samples (almonds, apricot kernels, chestnuts, hazelnuts, peanuts, pistachios, walnuts and Brazil nut) were analyzed using an High-Performance Liquid Chromatography system.

RESULTS

Twenty samples (16.1%) were contaminated with AFs of which 55% were non-compliant, according to Reg. 165/2010. The median values (µg/kg) of total AFs and AFB1 were 16.6 and 15.1, respectively. Pistachios appeared more susceptible to AF contamination than the other nuts, with levels of total AFs ranging from 8.8 to 387.3 µg/kg and of AFB1 from 8.2 to 354.5 µg/kg. The majority of contaminated samples came from Asia and AF contamination was different in the various Asiatic sub-regions: regardless of the type of nuts, samples from Western Asia were the least contaminated.

CONCLUSIONS

As geographical origin may influence the risk of contamination, in order to protect human health, customer countries should increase AF monitoring in nuts coming from those countries with favorable environments for the growth of aflatoxigenic molds or with less strict regulations.

A One-Step Chemical Strategy for the Formation of Carbon Nanotube Junctions in Aqueous Solution: Reaction of DNA-Wrapped Carbon Nanotubes with Diazonium Salts

A single-step chemical strategy allows the formation of single-walled carbon nanotube (SWCNT) molecular junctions in aqueous solution. SWCNTs were first wrapped with DNA to be water soluble and solution processable. Diazonium salts, which have been shown to react spontaneously with carbon nanotubes in water at room temperature, were then employed to covalently link SWCNT segments. The DNA wrapping of the nanotubes acted as a protective layer that limits the functionalization predominantly to the nanotube terminal ends, therefore allowing the assembly of linear SWCNT junctions. Upon increasing the concentration of the linker, we observed first the formation of side-to-end junctions, and eventually the assembly, through side-to-side interactions, of SWCNTs into bundles. This approach demonstrates the possibility of tuning the formation of linear and branched carbon nanotube junctions that in turn is of importance for the sustainable fabrication of solution-processable CNT-based nanoscale systems and devices.

Amyloid-β oligomers have a profound detergent-like effect on lipid membrane bilayers, imaged by atomic force and electron microscopy

The ability of amyloid-β peptide (Aβ) to disrupt membrane integrity and cellular homeostasis is believed to be central to Alzheimer's disease pathology. Aβ is reported to have various impacts on the lipid bilayer, but a clearer picture of Aβ influence on membranes is required. Here, we use atomic force and transmission electron microscopies to image the impact of different isolated Aβ assembly types on lipid bilayers. We show that only oligomeric Aβ can profoundly disrupt the bilayer, visualized as widespread lipid extraction and subsequent deposition, which can be likened to an effect expected from the action of a detergent. We further show that Aβ oligomers cause widespread curvature and discontinuities within lipid vesicle membranes. In contrast, this detergent-like effect was not observed for Aβ monomers and fibers, although Aβ fibers did laterally associate and embed into the upper leaflet of the bilayer. The marked impact of Aβ oligomers on membrane integrity identified here reveals a mechanism by which these oligomers may be cytotoxic.

Fast Determination of Phenolic Compounds in Rice Grains by Ultraperformance Liquid Chromatography Coupled to Photodiode Array Detection: Method Development and Validation

There are several phenolic compounds in rice grains providing benefits for human health. The concentration of phenolic compounds in rice is strongly affected by the polishing steps during rice production. A new sensitive ultraperformance liquid chromatography-ultraviolet-visible spectroscopy method with a photodiode array detection protocol has been developed and validated for the quantitation of phenolic compounds in rice grains. Several working variables and two different columns were evaluated. Finally, a less than 3 min analysis time was developed to achieve enough resolution for the simultaneous determination of the 20 most common phenolic compounds in rice. The analytical properties for the separation method produced an adequate sensitivity for all phenolic compounds in the regular range for phenolics in rice, 0.5-100 mg L^-1 ( R² > 0.997), with high precisions for both repeatability and intermediate precisions (coefficients of variation less than 0.4 and 2.5% for the retention time and area of the peaks, respectively).

DNA Origami Nanoarrays for Multivalent Investigations of Cancer Cell Spreading with Nanoscale Spatial Resolution and Single-Molecule Control

We present a strategy for the fabrication of biomimetic nanoarrays, based on the use of DNA origami, that permits the multivalent investigation of ligand-receptor molecule interactions in cancer cell spreading, with nanoscale spatial resolution and single-molecule control. We employed DNA origami to control the nanoscale spatial organization of integrin- and epidermal growth factor (EGF)-binding ligands that modulate epidermal cancer cell behavior. By organizing these multivalent DNA nanostructures in nanoarray configurations on nanopatterned surfaces, we demonstrated the cooperative behavior of integrin and EGF ligands in the spreading of human cutaneous melanoma cells: this cooperation was shown to depend on both the number and ratio of the selective ligands employed. Notably, the multivalent biochips we have developed allowed for this cooperative effect to be demonstrated with single-molecule control and nanoscale spatial resolution. By and large, the platform presented here is of general applicability for the study, with molecular control, of different multivalent interactions governing biological processes from the function of cell-surface receptors to protein-ligand binding and pathogen inhibition.

Assembly of graphene nanoflake-quantum dot hybrids in aqueous solution and their performance in light-harvesting applications

Graphene nanoflakes and CdSe/ZnS quantum dots were covalently linked in environmentally friendly aqueous solution. Raman spectroscopy and photoluminescence studies, both in solution and on surfaces at the single nanohybrid level, showed evidence of charge transfer between the two nanostructures. The nanohybrids were further incorporated into solar cell devices, demonstrating their potential as light harvesting assemblies.

Tuning the Coupling in Single-Molecule Heterostructures: DNA-Programmed and Reconfigurable Carbon Nanotube-Based Nanohybrids

Herein a strategy is presented for the assembly of both static and stimuli-responsive single-molecule heterostructures, where the distance and electronic coupling between an individual functional nanomoiety and a carbon nanostructure are tuned via the use of DNA linkers. As proof of concept, the formation of 1:1 nanohybrids is controlled, where single quantum dots (QDs) are tethered to the ends of individual carbon nanotubes (CNTs) in solution with DNA interconnects of different lengths. Photoluminescence investigations-both in solution and at the single-hybrid level-demonstrate the electronic coupling between the two nanostructures; notably this is observed to progressively scale, with charge transfer becoming the dominant process as the linkers length is reduced. Additionally, stimuli-responsive CNT-QD nanohybrids are assembled, where the distance and hence the electronic coupling between an individual CNT and a single QD are dynamically modulated via the addition and removal of potassium (K+) cations; the system is further found to be sensitive to K+ concentrations from 1 pM to 25 × 10-3 m. The level of control demonstrated here in modulating the electronic coupling of reconfigurable single-molecule heterostructures, comprising an individual functional nanomoiety and a carbon nanoelectrode, is of importance for the development of tunable molecular optoelectronic systems and devices.