Abstract Systemic lupus erythematosus (SLE) or lupus is an autoimmune disease that affects more than 5 million people worldwide, including 1.5 million Americans. Nearly 60% of these patients will develop lupus nephritis, which can cause kidney failure. Thus, its financial burden to individual patient can reach $70,000/year, much higher than many other diseases because of kidney transplantation. Although early treatment of lupus nephritis can significantly slow down or even prevent the disease progression to kidney failure, proteinuria, our current clinical standard for screening lupus patients, is not sensitive and accurate enough for early detection of lupus nephritis. While new endogenous biomarkers or exogenous markers are being tested in clinical trials for early diagnosis of lupus nephritis, none of them has outperformed proteinuria in the clinics. As a result, even today, proteinuria remains the clinical standard and there are strong unmet needs for early detection and accurate monitoring of kidney damages in the lupus patients. To address this unmet need, ClearNano Inc. is developing a test agent, named “ClearGold” that can be used as an exogenous urine marker to detect lupus nephritis much earlier and more accurately than proteinuria. Sponsored by previous STTR Phase I grant, using a renal clearable gold nanoparticle as a prototype test agent, ClearNano has successfully validated the feasibility of ClearGold in detection and staging of lupus nephritis in mouse model much earlier and more accurately than proteinuria, and found it also outperformed other classical endogenous and exogenous markers being evaluated in the clinical trials for lupus nephritis detection. In this STTR Phase II application, we will identify a lead product, develop large-scale synthesis under Good Laboratory Practice (GLP) guidelines and conduct in-house toxicity study in rat model. The success will allow us to prepare a strong package for pre-Investigational New Drug (IND) meeting with FDA, reduce the risk for comprehensive toxicology studies carried by CRO, and accelerate the clinical translation of this novel nanotechnology; so that a long-standing unmet need in the early detection of lupus nephritis can be eventually addressed with our “ClearGold” test agent, which represents a $1.6 Billion market opportunity.