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Ersin Sar&inodot;çam,1,2 Ali Do&gbreve;an Dursun,3,4 Gülçin Türkmen Sar&inodot;y&inodot;ld&inodot;z,5,6 Nalan Can,7 Engin Bozkurt,1 U&gbreve;ur Gönüllü,8 Nihal Basay,9 Meral Türkmen,10 Abdülaziz Denli,11 Mustafa Ünlü12 1Department of Cardiology, Medicana International Ankara Hospital, Ankara, Turkey; 2Department of Cardiology, At&inodot;l&inodot;m University Medical School, Ankara, Turkey; 3Department of Physiology, At&inodot;l&inodot;m University Medical School, Ankara, Turkey; 4Check-up Center, Home Care Services, Medicana International Ankara Hospital, Ankara, Turkey; 5Department of General Surgery, Medicana International Ankara Hospital, Ankara, Turkey; 6Operating Room Services, Vocational School of Health Services, At&inodot;l&inodot;m University, Ankara, Turkey; 7Department of Nuclear Medicine, Medicana International Ankara Hospital, Ankara, Turkey; 8Department of Pulmonary Medicine, At&inodot;l&inodot;m University Medical School, Ankara, Turkey; 9Department of Pulmonary Medicine, Medicana International Ankara Hospital, Ankara, Turkey; 10Department of Internal Medicine, Medicana International Ankara Hospital, Ankara, Turkey; 11Department of Physical Medicine and Rehabilitation, Medicana International Ankara Hospital, Ankara, Turkey; 12Department of Nuclear Medicine, Gazi University Medical School, Ankara, TurkeyCorrespondence: Ersin Sar&inodot;çamDepartment of Cardiology, Medicana International Ankara Hospital, Sö&gbreve;ütözü Cd. 2165. Sokak No: 6, Sö&gbreve;ütözü, Ankara, 06520, TurkeyTel +90 5324066440Fax +90 3122203170Email saricamersin@yahoo.comBackground: In the post-acute COVID-19 syndrome, many patients suffer from palpitations, effort-associated fatigue, and even sudden death. The mechanism of heart involvement in this syndrome is uncertain. The main purpose of the study was to identify possible cardiac involvement causes in patients with post-acute COVID-19 by using biomarkers such as NT-proBNP and nitric oxide (NO) and cardiac imaging modalities.Methods: In this cross-sectional study, a total of 105 participants were included according to the existence of symptoms, and 40 of these participants were asymptomatic patients. The ages of the participants ranged from 20 to 50 years. All patients were healthy before COVID-19. The symptoms were defined as palpitations and/or fatigue association with exercise in post-acute COVID-19 term. The comparison of the two groups was made by using biochemical parameters (NT-proBNP, Troponin I, NO) and imaging techniques (echocardiography, cardiovascular magnetic resonance (CMR) and cardiac positron emission tomography (PET)).Results: The symptomatic patients had higher NT-proBNP levels compared with asymptomatic patients (132.30± 35.15; 76.86± 16.79, respectively; p < 0.001). Interestingly, the symptomatic patients had lower NO levels than asymptomatic patients (9.20± 3.08; 16.15± 6.02, respectively; p < 0.001). Echocardiography and CMR were normal. However, we found regional increased 18F-FDG uptake on cardiac PET to be compatible with myocardial fatigue.Conclusion: We found elevated NT-proNBP levels, low serum NO levels, and increased 18F-FDG uptake on cardiac PET in post-acute COVID syndrome. Cardiac PET could replace or be added to CMR for detecting subtle subacute/chronic myocarditis. The follow-up of patients with post-acute COVID-19 could target the possibility of risk of heart failure.Keywords: post-acute COVID-19, cardiac involvement, laboratory tests, imaging

Biological nanoparticles such as viruses and exosomes are important biomarkers for a range of medical conditions, from infectious diseases to cancer. Biological sensors that detect whole viruses and exosomes with high specificity, yet without additional labeling, are promising because they reduce the complexity of sample preparation and may improve measurement quality by retaining information about nanoscale physical structure of the bio-nanoparticle (BNP). Towards this end, a variety of BNP biosensor technologies have been developed, several of which are capable of enumerating the precise number of detected viruses or exosomes and analyzing physical properties of each individual particle. Optical imaging techniques are promising candidates among broad range of label-free nanoparticle detectors. These imaging BNP sensors detect the binding of single nanoparticles on a flat surface functionalized with a specific capture molecule or an array of multiplexed capture probes. The functionalization step confers all molecular specificity for the sensor’s target but can introduce an unforeseen problem; a rough and inhomogeneous surface coating can be a source of noise, as these sensors detect small local changes in optical refractive index. In this paper, we review several optical technologies for label-free BNP detectors with a focus on imaging systems. We compare the surface-imaging methods including dark-field, surface plasmon resonance imaging and interference reflectance imaging. We discuss the importance of ensuring consistently uniform and smooth surface coatings of capture molecules for these types of biosensors and finally summarize several methods that have been developed towards addressing this challenge.

Gold nanoparticles (AuNPs) play a vital role in biotechnology, medicine, and diagnostics due to their unique optical properties. Their conjugation with antibodies, antigens, proteins, or nucleic acids enables precise targeting and enhances biosensing capabilities. Functionalized AuNPs, however, may experience reduced stability, leading to aggregation or loss of functionality, especially in complex biological environments. Additionally, they can show non-specific binding to unintended targets, impairing assay specificity. Within this work, citrate-stabilized and silica-coated AuNPs (GNPs and SiGNPs, respectively) have been coated using N,N-dimethylacrylamide-based copolymers to increase their stability and enable their functionalization with biomolecules. AuNP stability after modification has been assessed by a combination of techniques including spectrophotometric characterization, nanoparticle tracking analysis, transmission electron microscopy and functional microarray tests. Two different copolymers were identified to provide a stable coating of AuNPs while enabling further modification through click chemistry reactions, due to the presence of azide groups in the polymers. Following this experimental design, AuNPs decorated with ssDNA and streptavidin were synthesized and successfully used in a biological assay. In conclusion, a functionalization scheme for AuNPs has been developed that offers ease of modification, often requiring single steps and short incubation time. The obtained functionalized AuNPs offer considerable flexibility, as the functionalization protocol can be personalized to match requirements of multiple assays. [ABSTRACT FROM AUTHOR]

Wet Age-related macular degeneration (AMD) is the leading cause of vision loss in industrialized nations, often resulting in blindness. Biologics, therapeutic agents derived from biological sources, have been effective in AMD, albeit at a high cost. Due to the high cost of AMD treatment, it is critical to determine the binding affinity of biologics to ensure their efficacy and make quantitative comparisons between different drugs. This study evaluates the in vitro VEGF binding affinity of two drugs used for treating wet AMD, monoclonal antibody-based bevacizumab and fusion protein-based aflibercept, performing quantitative binding measurements on an Interferometric Reflectance Imaging Sensor (IRIS) system. Both biologics can inhibit Vascular Endothelial Growth Factor (VEGF). For comparison, the therapeutic molecules were immobilized on to the same support in a microarray format, and their real-time binding interactions with recombinant human VEGF (rhVEGF) were measured using an IRIS. The results indicated that aflibercept exhibited a higher binding affinity to VEGF than bevacizumab, consistent with previous studies using ELISA and SPR. The IRIS system's innovative and cost-effective features, such as silicon-based semiconductor chips for enhanced signal detection and multiplexed analysis capability, offer new prospects in sensor technologies. These attributes make IRISs a promising tool for future applications in the development of therapeutic agents, specifically biologics. [ABSTRACT FROM AUTHOR]