• Point of care medical device using Raman spectroscopy to diagnose Gout and Pseudogout

Monosodium urate monohydrate (MSU, causes gout) and calcium pyrophosphate dihydrate (CPPD, causes Pseudogout) are two main crystals leading to joint disease. Raman spectroscopic analysis of synovial aspirates carries a diagnostic potential. The aim of this work is to translate Raman spectroscopy to clinical applications by developing a cost-efficient and portable device that will diagnose crystal species at the point of care.

Figure 1. (a–c) Organic debris was dissolved by digestion; (d) before the  digestion, clinical crystals aggregated in the organic debris were visible in symptomatic samples; (e) after the digestion, crystals were uniformly released into the synovial fluid.                                                         

Synovial aspirates were obtained from Metro Health Hospital (Cleveland, OH) and Henry Ford Hospital (Detroit, MI). The synovial fluids were digested with chemicals (hyaluronidase, proteinase K, and SDS) to dissolve the organic debris and release the crystals. The digested synovial fluid was transferred to a syringe and filtered through a custom-made filter cartridge mounted at the syringe tip; the filter cartridge was designed to guide and constrict the flow of the fluid to a spot, retaining crystals over a ~1 mm diameter spot. Following the filtration, the filter cartridge was inserted into a cost-efficient automated Raman device (CARD) designed for diagnosis of crystal species.

Figure 2. (a) Customized microfiltration cartridge was inserted in the cost-efficient Raman device (CARD) for Raman spectroscopic analysis; (b) CARD is mainly composed of an OEM Raman module (1), a receptacle mounted on a translation stage to receive the cartridge (2), a servomotor to move the translation stage (3), and a microcontroller to control the servomotor (4); (c) Laser was directly delivered to the cartridge to illuminate the crystal deposit without having to take the membrane out.

 

By using CARD, the limits of detection of MSU and CPPD crystals were 0.1 μg/mL and 1 μg/mL respectively, far less than the reported concentrations (10 ~ 100 μg/mL). Based on the preliminary clinical study (N = 174), CARD carries a sensitivity of >90%, and a specificity of 100%. While detecting crystal species, CARD can estimate the crystal concentrations, which would relate to the disease severity. CARD has potential to be a novel tool for gout/pseudogout diagnosis.

Figure 3. (a) Microscopic image of the analyte retained on the microfilter membrane following the processing of the clinical sample collected from asymptomatic joint; (b) SEM image of clinical MSU crystals retained on the polypropylene filter membrane; (c) SEM image of individual clinical MSU crystals (needle shape); (d) The chemical image of clinical MSU crystal distribution over the spot generated by Raman mapping. The step size was 25 mm in both directions and there were overall 1444 points sampled to generate the mapping; (e) Representative Raman spectra (background corrected) from three different locations with low, medium and high Raman signal intensities. Colors of spectra are matched to reflect the colormap shown in ‘d’.

• Publications:

(1) Bolan Li, Shan Yang, Ozan Akkus. A customized Raman system for point-of-care detection of arthropathic crystals in the synovial fluid. Analyst, 2014, 139, pp 823-830.

(2) Shan Yangᶧ, Bolan Liᶧ, Mikhail N. Slipchenko, Anna Akkus, Nora G. Singer, Yener N. Yeni, Ozan Akkus, Laser Wavelength Dependence of Background Fluorescence in Raman Spectroscopic Analysis of Synovial Fluid from Symptomatic Joints. Journal of Raman Spectroscopy, 2013, 44(8), pp 1089-1095. (ᶧ Authors contributed equally)

(3) Shan Yang, Bolan Li, Anna Akkus, Ozan Akkus, Lisa Lang. Wide-field Raman imaging of dental lesions. Analyst, 2014, 139, pp 3107-3114.

• Conferences

(1) Shan Yang, Bolan Li, Anna Akkus, Ozan Akkus, Lisa Lang. Wide-field Raman Imaging of Dental Lesions. IADR/AADR/CADR Conference. 2015, Boston, MA, USA.

(2) Nora Singer, Bolan Li, Yener Yeni, Emma Barnboym, Steven Lewis, Daniel Oravec, Donald Haggins, Ozan Akkus. Raman Spectroscopy: Point of Service Diagnosis is Sensitive and Specific – A Tool for Improving Accuracy and Reducing Future Hospital Admission. 2014 ACR/ARHP Annual Meeting, Boston, MA, USA.

(3) Bolan Li, Shan Yang, Ozan Akkus, Nora Singer, Emma Barnboym, Donard G. Haggins, Yener N. Yeni, An Automated Raman Device for Point-of-Care Diagnosis of Crystal-Based Arthropathies, 2014 MBECC, Detroit, MI, USA.

(4) Bolan Li, Shan Yang, Ozan Akkus, An Automated Raman Device for Gout Diagnosis. CLEO, 2013, June. San Jose, CA, USA.

(5) Shan Yang, Bolan Li, Ozan Akkus, Dental Caries Detection via Global Raman Imaging. CLEO, 2013, June. San Jose, CA, USA