1 Title: DESIGN, DEVELOPMENT, AND VALIDATION OF A NANOBIOSENSOR TO DETECT CIRCULATING MICROBIOME FOR CARDIOVASCULAR DISEASE RISK ASSESSMENT Authors: Nazim Nazeer, Rakhi Dewangan, Kaniz Zaidi, Vikas Gurjar, Rajnarayan Tiwari, Pradyumna Kumar Mishra* Affiliations: Division of Environmental Biotechnology, Genetics & Molecular Biology (EBGMB) ICMR-National Institute for Research in Environmental Health (NIREH), Bhopal, India Abstract Cardiovascular disease (CVD) is a serious worldwide health concern that necessitates the development of novel diagnostic techniques for early identification and personalized healthcare management. Even before the insights provided by gut microbiota, current research has demonstrated the importance of circulating microbiome (CMB) in the evolution of cardiometabolic illness risk and progression. We developed a nanobiosensor that uses specific labeled capture probes with perovskite quantum dots (PQDs) to detect the targeted 16S rRNA sequences in the peripheral milieu. With ideal applicability, specificity, and sensitivity, this sensor delivers unique insights into the presence and characterization of circulating microbiota signatures. Developing a nanophotonic microbiome detection method in body fluids may pave the way for creating a distinctive tool for CVD risk prediction for population-based screening programs in low and middle-income countries. Key Words: Gut Microbiome; Gut Microbiota Dysbiosis; Nanophotonic Optical Sensor; Nanophotonic Assay; Nanosensor; Non-Communicable Diseases; Cell-free Circulating Nucleic Acids; Translational Research Running Title: Nanobiosensor for circulating microbiome *Author for Correspondence: Prof. (Dr.) Pradyumna Kumar Mishra MSc, PhD, Fulbright-Nehru Fellow (USA), AIMF (DBT-Wellcome Trust & AAS), FAMS Scientist - F & Head Division of Environmental Biotechnology, Genetics & Molecular Biology (EBGMB) ICMR-National Institute for Research in Environmental Health (NIREH) NIREH Campus, Bypass Road, Bhauri, Bhopal - 462030 (MP), India e-mail: pkm_8bh@yahoo.co.uk https://orcid.org/0000-0002-0795-2819 All rights reserved. No reuse allowed without permission. perpetuity. preprint (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in The copyright holder for this this version posted August 8, 2023. ; https://doi.org/10.1101/2023.08.05.23293588 doi: medRxiv preprint NOTE: This preprint reports new research that has not been certified by peer review and should not be used to guide clinical practice.