Leadership Team
Leroy Chimilio, Ph.D.
Dr. Leroy A. Chimilio is the Co-Founder and Chief Scientific Officer of YES, a specialty solvent and buffer manufacturing startup dedicated to delivering high-purity, precision-formulated buffer systems for pharmaceutical, biotech, and industrial applications. With more than 25 years of expertise in analytical chemistry, quality control, and method development, Dr. Chimilio brings a proven track record of designing, producing, and validating solutions that meet the most rigorous industry standards.
Prior to founding YES, Dr. Chimilio served as Manager of Quality Control at Greenfield Global, where he led a GMP-compliant QC team overseeing raw material testing, analytical method development, and third-party laboratory partnerships. He implemented advanced quality systems that ensured FDA and ISO compliance while driving major improvements in data integrity, laboratory efficiency, and regulatory readiness.
His career includes leadership roles at Ascensia Diabetes Care, SGS, Hoffman-La Roche, and TEVA Pharmaceuticals, where he directed analytical method development and validation for both small- and large-molecule pharmaceuticals, supported global product launches, and successfully guided QC and analytical teams through FDA audits. Recognized for building high-performing teams and managing complex technical projects, Dr. Chimilio has consistently delivered results across the product lifecycle.
Dr. Chimilio earned his Ph.D. in Physical Organic Chemistry from the University of Kansas, where his research centered on photochemical reaction mechanisms and preformulation strategies for anticancer agents. He completed postdoctoral work in pharmaceutical chemistry at the Higuchi Biosciences Center, contributing to advancements in drug stability, cyclodextrin chemistry, and solubility enhancement.
A scientist, innovator, and entrepreneur, Dr. Chimilio has authored peer-reviewed research, led global technology transfers, and built analytical laboratories from the ground up. His vision for YES is to establish a reliable, agile, and technically excellent partner in the life sciences supply chain—delivering quality, consistency, and innovation with every batch. Under his leadership, YES is positioned to become a trusted name in GMP-compliant buffer solutions, supporting the next generation of therapeutic and industrial innovation.
Nathan Renigar
As Co-Founder and Chief Operating Officer, Nathan Renigar brings over 15 years of leadership in GMP-regulated pharmaceutical manufacturing and CDMO operations, with a proven record of building high-performing organizations, ensuring regulatory readiness, and delivering measurable business results. His career spans pivotal roles in compliance, quality assurance, operational quality, project management, and business development, culminating in a skill set that blends strategic oversight with hands-on execution. Notably, he played a key role in a start-up CDMO pharmaceutical company, where he designed and implemented business development, project management, and operational processes from the ground up. These scalable systems not only accelerated growth and strengthened client relationships but also positioned the company for acquisition by a global pharmaceutical organization.
His expertise covers the full spectrum of quality systems and operational performance—CAPA and deviation investigations, supplier qualification, risk management, SOP development, and process optimization—supported by the utilization of Lean Six Sigma methodologies and Project Management Professional principles. Backed by a B.S. in Chemistry (Honors) and early-career experience in analytical chemistry and R&D, he combines technical depth with leadership agility. He has successfully led cross-functional teams to increase manufacturing output, streamline processes, and resolve complex quality events while fostering a culture of accountability, collaboration, and continuous improvement.
In his role as COO, Mr. Renigar applies his operational expertise, disciplined execution, and strategic vision to establish a high-performing, investor-ready organization. With a history of creating value in both start-up and established regulated environments, he is well-positioned to guide the company toward sustainable growth, operational efficiency, and long-term market leadership in the life sciences sector.