Decrystallization of Crystals Using Gold “Nano-Bullets” and the Metal-Assisted and Microwave-Accelerated Decrystallization Technique

Abstract

Gout is caused by the overproduction of uric acid and the inefficient metabolism of dietary purines in humans. Current treatments of gout, which include anti-inflammatory drugs, cyclooxygenase-2 inhibitors, and systemic glucocorticoids, have harmful side-effects. Our research laboratory has recently introduced an innovative approach for the decrystallization of biological and chemical crystals using the Metal-Assisted and Microwave-Accelerated Evaporative Decrystallization (MAMAD) technique. In the MAMAD technique, microwave energy is used to heat and activate gold nanoparticles that behave as “nano-bullets” to rapidly disrupt the crystal structure of biological crystals placed on planar surfaces. In this study, crystals of various sizes and compositions were studied as models for tophaceous gout at different stages (i.e., uric acid as small crystals (~10–100 μm) and L-alanine as medium (~300 μm) and large crystals (~4400 μm). Our results showed that the use of the MAMAD technique resulted in the reduction of the size and number of uric acid and L-alanine crystals up to >40% when exposed to intermittent microwave heating (up to 20 W power at 8 GHz) in the presence of 20 nm gold nanoparticles up to 120 s. This study demonstrates that the MAMAD technique can be potentially used as an alternative therapeutic method for the treatment of gout by effective decrystallization of large crystals, similar in size to those that often occur in gout.

Metal-Assisted and Microwave-Accelerated Decrystallization: An Alternative Approach to Potential Treatment of Crystal Deposition Diseases

“…Figure 5B [38] shows that the crystallinity of the UA remained unchanged in the presence of Au NPs at both room temperature and after exposure to microwave heating. Scanning Electron Microscopy (SEM) images in Figure 5C [38] further support these findings by highlighting that the decrease in sizes obtained was as a result of a physical breakdown and not a change in chemical composition of the crystals.…”

“…Microwave heating at 2 W to 20 W in the presence of Au NPs were used for the decrystallization of UA crystals at 0.1 mg/mL. Figure 5A [38] shows that the 2 W and 10 W power levels decrease crystal count by approximately 57% and 54%, respectively. However, in the control experiments (UA without Au NPs), the extent of decrease for the 2 W and 10 W power level was only 18% and 19% respectively.…”

“…The proof-of-principle demonstration of the MA-MAD technique was carried out for the decrystallization of UA crystals on a planar glass surface [38]. UA is the surgery, finding alternative remedies for gout is an important goal for researchers worldwide.…”

“…As will be demonstrated further along in the text, the medical microwave increases the efficiency of the MAMAD technique by reducing application time significantly. Figure 4A [38] shows the experimental apparatus used throughout the UA and (MSUM) decrystallization experiments. As shown in Figure 4B [38], the MAMAD technique was carried out in a similar fashion as previously described with UA on collagen coated glass.…”

“…In this regard, L-alanine crystals, which are much larger (up to 4.5 mm), were selected as a more ideal model for tophaceous gout. The experimental design for the decrystallization of L-alanine crystals using the MAMAD technique is shown in Figure 4B [38]. In a control experiment, L-alanine crystals without Au NPs are exposed to microwave heating.…”