Capacitive immunosensing at gold nanoparticle-decorated reduced graphene oxide electrodes fabricated by one-step laser nanostructuration

Nanostructured electrochemical biosensors have ushered in a new era of diagnostic precision, offering enhanced sensitivity and specificity for clinical biomarker detection. Among them, capacitive biosensing enables ultrasensitive label-free detection of multiple molecular targets. However, the complexity and cost associated with conventional fabrication methods of nanostructured platforms hinder the widespread adoption of these devices. This study introduces a capacitive biosensor that leverages laser-engraved reduced graphene oxide (rGO) electrodes decorated with gold nanoparticles (AuNPs). The fabrication involves laser-scribed GO-Au3+ films, yielding rGO-AuNP electrodes, seamlessly transferred onto a PET substrate via a press-stamping methodology. These electrodes have a remarkable affinity for biomolecular recognition after being functionalized with specific bioreceptors. For example, initial studies with human IgG antibodies confirm the detection capabilities of the biosensor using electrochemical capacitance spectroscopy. Furthermore, the biosensor can quantify CA-19-9 glycoprotein, a clinical cancer biomarker. The biosensor exhibits a dynamic range from 0 to 300 U mL-1, with a limit of detection of 8.9 U mL-1. Rigorous testing with known concentrations of a pretreated CA-19-9 antigen from human fluids confirmed their accuracy and reliability in detecting the glycoprotein. This study signifies notable progress in capacitive biosensing for clinical biomarkers, potentially leading to more accessible and cost-effective point-of-care solutions.

Glycan-Based Electrochemical Biosensors: Promising Tools for the Detection of Infectious Diseases and Cancer Biomarkers

Glycan-based electrochemical biosensors are emerging as analytical tools for determining multiple molecular targets relevant to diagnosing infectious diseases and detecting cancer biomarkers. These biosensors allow for the detection of target analytes at ultra-low concentrations, which is mandatory for early disease diagnosis. Nanostructure-decorated platforms have been demonstrated to enhance the analytical performance of electrochemical biosensors. In addition, glycans anchored to electrode platforms as bioreceptors exhibit high specificity toward biomarker detection. Both attributes offer a synergy that allows ultrasensitive detection of molecular targets of clinical interest. In this context, we review recent advances in electrochemical glycobiosensors for detecting infectious diseases and cancer biomarkers focused on colorectal cancer. We also describe general aspects of structural glycobiology, definitions, and classification of electrochemical biosensors and discuss relevant works on electrochemical glycobiosensors in the last ten years. Finally, we summarize the advances in electrochemical glycobiosensors and comment on some challenges and limitations needed to advance toward real clinical applications of these devices.

AB0020 COMPARATIVE DESCRIPTION OF CYTOKINES AND MATRIX METALLOPROTEINASES IN A GROUP OF PATIENTS WITH RHEUMATOID ARTHRITIS AND OSTEOARTHROSIS UNDER A STRICT FOLLOW-UP COMPARED WITH COVID-19 PATIENTS

Background

COVID-19, rheumatoid arthritis (RA) and osteoarthrosis (OA) are diseases characterized by the secretion of cytokines related to the stimulation of the inflammatory response.

Objectives

To identify the differences in the cytokine and matrix metalloproteinases (MMP) profile within one acute infectious disease and two chronic inflammatory rheumatic diseases.

Methods

Analytical cross-sectional study. RA patients under a strict follow-up program (T2T evaluated every two months), OA patients without strict clinical follow-up, evaluated once or twice a year, and Severe (mortality) COVID-19 patients were included. Eleven proteins (cytokines, MMPs and its tissue inhibitors) were quantified through Luminex multiplex assay in serum samples. Univariate and bivariate analyzes were performed. Approval of Ethics Committee and informed consent were obtained.

Results

A total of 108 patients with RA and OA were compared with 20 severe COVID-19 patients. There were no significant differences through the method of Kruskall–Wallis, between RA and OA patients. IL1-B and MMP-2 were significantly lower in COVID-19 patients. Levels of IL-10, IL-1RA, IL-6, MMP-1, MMP-9, and TIMP-1 were significantly higher in COVID-19 patients. There were no differences in TNF-A, TIMP-2 and INF-G. (Table 1)

Table 1.

Significant correlations between cytokines related to Covid-19, RA and OR.

Cytokine (pg/ml) Median valuesRA (%)OACOVID-19P-valueIL-1054.9254.49116.38<0.0001aIl1-RA62.1951.82110.08<0.0001aIL1-B67.0955.3046.170.045IL-656.0951.3484.98<0.0001b 0.003cTNF-A17.514.616.3NSMMP-1d57.8454.8490.81<0.0001b 0.045cMMP-2 d70.3870.5948.560.040MMP-9 d66.2558.1686.40.007 bTIMP-1 d51.5960.99111.67<0.0001aTIMP-2 d45.247.749.6NSINF-G5.755.323.07NS

a Between RA and Covid-19 and OA and Covid-19, without differences between RA and OA. b Between OA and Covid-19.

C Between RA and Covid-19. d ng/ml.

Conclusion

Compared with RA and OA patients, severe COVID-19 patients have a great impact on the cytokines and MMPs addressed in this study, proving that COVID-19 patients suffer from a cytokine storm [1] when severely infected.

References

[1]R. Mulchandani, T. Lyngdoh, and A. K. Kakkar, “Deciphering the COVID-19 cytokine storm: Systematic review and meta-analysis,” Eur. J. Clin. Invest., vol. 51, no. 1, pp. 1–21, 2021, doi: 10.1111/eci.13429.

Disclosure of Interests

None declared

AB0250 DESCRIPTION OF ARTERIAL STIFFNESS, INFLAMMAGING AND VASCULAR AGE IN A GROUP OF PATIENTS WITH RHEUMATOID ARTHRITIS UNDER A STRICT FOLLOW-UP COMPARED WITH UNCONTROLLED OSTEOARTHRITIS PATIENTS

Background

The risk of cardiovascular disease (CVD) in patients with rheumatoid arthritis (RA) is higher than in individuals in the general population. The fundamental risk factor for CVD is age, related to alterations at the arterial level, called vascular aging reflected by arterial stiffness and endothelial dysfunction

Objectives

The aim of the study was to compare vascular age and arterial stiffness (PWV-Pulse Wave Velocity) in two groups of patients with RA and with osteoarthritis (OA) and to assess the influence of inflammaging (persistent low-grade inflammation that develops with age) and metabolic markers in these outcomes.

Methods

Analytical cross-sectional study. RA patients under a strict follow-up program (T2T evaluated every two months) and OA patients without strict clinical follow-up, evaluated once or twice a year, were included. Patients with history of uncontrolled hypertension, CVD and/or current smoking were excluded. Waist-hip ratio, body mass index (BMI), DAS28 (RA), C-Reactive protein (CRP), Erythrocyte sedimentation rate (ESR), glycemia and lipid profile were measured. PWV and vascular age (in years) were evaluated through oscillometric method, arteriograph-TensioMed. Eleven proteins components of the inflammaging (cytokines, Matrix metalloproteinases - MMPs and its tissue inhibitors), were quantified through Luminex multiplex assay in serum samples. Univariate and bivariate analyzes (Chi-square and non-parametric correlations) were performed. Approval of Ethics Committee and informed consent were obtained.

Results

A total of 106 patients (74% women) were included (52/RA and 54/OA). Mean age was 57±5.6 years without differences between groups. There were significant differences in CRP and ESR (higher in RA) and in BMI, waist circumference and weight (higher in OA). RA patients had low disease activity level (DAS28: Median 2.6, IQR 1.3). There were no differences in PWV, vascular age or inflammaging (except for MMP-1, higher in RA), between the groups. PWV had a positive correlation with LDL (Rho Coef. 0.218 p=0.025). Patients who performed physical activity had a lower vascular age than those who did not [43 Interquartile range (IQR)23 vs 60 IQR 17, p=0.032). Vascular age was higher in RA patients who did not receive methotrexate 60 (IQR 19.3) compared with patients under methotrexate treatment 44.5 (IQR 23) (p = 0.017). Also, vascular age was lower in OA patients under prescribed physical activity (43 IQR 24.8 vs 56.5 IQR 20, p=0.03). MMP-9 in RA patients (Rho 0.283, p=0.042) and IL-10 in OA patients (Rho 0.290, p= 0.036) correlated with diastolic pressure. The components of inflammaging did not correlate with vascular age. The Framingham Risk Score was strongly associated with vascular age.

Table 1.

Significant correlations with vascular age

VariableSpearman’s Rhop-valueLDL levels0.2000.040Systolic blood pressure0.3000.002Mean arterial blood pressure0.2100.031Daily coffee cups intake-0.2120. 045Framingham Risk Score0.340<0.0001MDHAQ score in RA patients0.4170.002

LDL: low density lipoprotein; MDHAQ: multidimensional health assessment questionnaire.

Conclusion

In RA strictly controlled patients, there are no differences in endothelial dysfunction, vascular age or inflammaging, when comparing with uncontrolled overweight OA patients. Physical activity, LDL levels and coffee consumption corelate with vascular age in OA and RA patients. OA patients under physiatrists follow-up and RA patients under methotrexate treatment or with low MDHAQ levels have lower vascular age levels.

References

[1]Inflammaging as a link between autoimmunity and cardiovascular disease: the case of rheumatoid arthritis. Santos-Moreno P, Burgos-Angulo G, Martinez-Ceballos MA, et al Inflammaging as a link between autoimmunity and cardiovascular disease: the case of rheumatoid arthritis. RMD Open. 2021 Jan;7(1):e001470

Disclosure of Interests

None declared

Phosphoglycan-sensitized platform for specific detection of anti-glycan IgG and IgM antibodies in serum

Glycosylphosphatidylinositol anchored proteins (GPI-APs) are natural conjugates in the plasma membrane of eukaryotic cells that result from the attachment of a glycolipid to the C-terminus of many proteins. GPI-APs play a crucial role in cell signaling and adhesion and have implications in health and diseases. GPI-APs and GPIs without protein (free GPIs) are found in abundance on the surface of the protozoan parasite Toxoplasma gondii. The detection of anti-GPI IgG and IgM antibodies allows differentiation between toxoplasmosis patients and healthy individuals using serological assays. However, these methods are limited by their poor efficiency, cross-reactivity and need for sophisticated laboratory equipment and qualified personnel. Here, we established a label-free electrochemical glycobiosensor for the detection of anti-GPI IgG and IgM antibodies in serum from toxoplasmosis seropositive patients. This biosensor uses a synthetic GPI phosphoglycan bioreceptor immobilized on screen-printed gold electrodes through a linear alkane thiol phosphodiester. The antigen-antibody interaction was detected and quantified by electrochemical impedance spectroscopy (EIS). The resultant device showed a linear dynamic range of anti-GPI antibodies in serum ranging from 1.0 to 10.0 IU mL^-1, with a limit of detection of 0.31 IU mL^-1. This method also holds great potential for the detection of IgG antibodies related to other multiple medical conditions characterized by overexpression of antibodies.

Electrochemical Biosensors for Determination of Colorectal Tumor Biomarkers

The accurate determination of specific tumor markers associated with cancer with non-invasive or minimally invasive procedures is the most promising approach to improve the long-term survival of cancer patients and fight against the high incidence and mortality of this disease. Quantification of biomarkers at different stages of the disease can lead to an appropriate and instantaneous therapeutic action. In this context, the determination of biomarkers by electrochemical biosensors is at the forefront of cancer diagnosis research because of their unique features such as their versatility, fast response, accurate quantification, and amenability for multiplexing and miniaturization. In this review, after briefly discussing the relevant aspects and current challenges in the determination of colorectal tumor markers, it will critically summarize the development of electrochemical biosensors to date to this aim, highlighting the enormous potential of these devices to be incorporated into the clinical practice. Finally, it will focus on the remaining challenges and opportunities to bring electrochemical biosensors to the point-of-care testing.

P2273Predictors of short- and mid-term outcomes after TAVR in low-flow, low-gradient aortic stenosis

Background

There is a lack of data on outcomes in classical (C-LFLG) and paradoxical low-flow, low-gradient aortic stenosis (P-LFLG) patients undergoing TAVR.

Purpose

We aim to compare baseline characteristic and procedural outcomes between C-LFLG, P-LFLG and high-gradient aortic stenosis (HG-AS) patients undergoing TAVR.

Methods

Patients included in the Transcatheter RegistrY of aorTic valve biOprosthesis in Latin-AMerica (TRYTOM Registry) were divided in 3 groups: 1) HG-AS: mean transaortic gradient (MG) ≥40 mmHg; 2) P-LFLG: MG <40 mmHg and left ventricular ejection fraction (LVEF) ≥50%; 3) C-LFLG: MG <40 mmHg and LVEF <50%. The outcomes were evaluated at 30-days and 1-year and were classified according to definitions of the VARC-2.

Results

1040 patients were included, 677 (65%) classified as HG-AS, 223 (21%) as P-LFLG and 140 (14%) as C-LFLG. Median follow-up was 16 months (range 0–109). There were baseline differences between HG-AS, P-LFLG and C-LFLG regarding age (80±7 vs 80±5 vs 78±8 years, respectively; p=0.017), NYHA FC III and IV (61.0 vs 72.6 vs 83.6%, respectively; p<0.001), coronary artery disease (44.1 vs 47.1 vs 57.9%, respectively; p=0.012), EuroSCORE II (7.2±6.3 vs 7.5±5.0 vs 12.9±10.4%, respectively; p<0.001), LVEF (56±11 vs 61±7 vs 32±9%, respectively; p<0.001), MG (53±13 vs 30±6 vs 27±7 mmHg, respectively; p<0.001), aortic valve area (0.65±0.16 vs 0.74±0.15 vs 0.70±0.16 cm2, respectively; p<0.001) and creatinine (1.2±0.7 vs 1.1±0.5 vs 1.5±1.3 mg/dl, respectively; p<0.001). Despite these significant baseline differences, we found similar outcomes after TAVR between HG-AS, P-LFLG and C-LFLG regarding device success (89.8 vs 95.1 vs 90.7%, respectively; p=0.057), in-hospital mortality (6.1 vs 5.9 vs 11.8%, respectively; p=0.144) and all other VARC-2 major outcomes, including major bleeding, major vascular complication and disabling stroke. In addition, female sex (OR 2.13, 95% CI 1.16–3.92, p=0.014), LVEF (OR 1.02, 95% CI 1.00–1.04, p=0.039) and MG (OR 0.97, 95% CI 0.95–0.99, p=0.004) were the only predictor of device success by multivariate analysis. Furthermore, 1-year mortality was similar among the groups (9.5 vs 8.3 vs 14.3%, respectively; p=0.358; Figure 1), and by multivariate analysis, diabetes (HR 2.44, 95% CI 1.10–5.41, p=0.028), creatinine (HR 1.65, 95% CI 1.17–2.33, p=0.004), conversion to general anesthesia (HR 7.93, 95% CI 2.08–30.20, p=0.002) and post-procedure disabling stroke (HR 12.84, 95% CI 3.09–53.40, p<0.001) predicted increased 1-year mortality, irrespective on the LVEF and MG.

Conclusions

Apart from baseline differences, TAVR in P-LFLG and C-LFLG was feasible and with similar clinical outcomes when compared to HG-AS. Mid-term mortality rates was associated with diabetes, creatinine and procedure complications.

Microalgae protoplasts isolation and fusion for biotechnology research

Protoplasts are microbial or vegetable cells lacking a cell wall. These can be obtained from microalgae by an enzymatic hydrolysis process in the presence of an osmotic stabilizer. In general, protoplasts are experimentally useful in physiological, geneticand bio-chemical studies, so their acquisition and fusion will continue to be an active research area in modern biotechnology. The fusion of protoplasts in microalgae constitutes a tool for strain improvement because it allows both intra and interspecific genetic recombina-tion, resulting in organisms with new or improved characteristics of industrial interest. In this review we briefly describe themethod-ology for obtaining protoplasts, as well as fusion methods and the main applications of microalgal platforms.