Frozen organs could be brought back to life safely one day with the aid of nanotechnology, anew study finds. The development could help make donated organs available for virtuallyeveryone who needs them in the future, the researchers say. In the new work, scientistsdeveloped a way to safely thaw frozen tissues with the aid of nanoparticles — particles onlynanometers or billionths of a meter wide.
       The scientists tested their method on frozen human skin cells, segments of pig heart valvesand sections of pig arteries. None of the rewarmed tissues displayed signs of harm from theheating process, and they preserved key physical properties such as elasticity. Moreover, theresearchers were able to wash away the nanoparticles from the sample after thawing. However,nanotechnology is still at the level of rabbit organs now. As for human organs, Nanotech is still along way to go.
       The number of donated organs that could be transplanted into patients could increase greatlyif there were a way to freeze and reheat organs without damaging the cells within them. Theresearchers manufactured silica-coated nanoparticles that contained iron oxide. When theyapplied a magnetic field to frozen tissues suffused with the nanoparticles, the nanoparticlesgenerated heat rapidly and uniformly. The tissue samples warmed up at rates of up to more than260 degrees Fahrenheit (130 degrees Celsius) per minute, which is 10 to 100 times faster thanprevious methods.
       Since the first successful kidney transplant in 1954, organ transplantation has saved thelives of hundreds of thousands of patients. If it weren't for the large and growing shortage ofdonor organs, the life-saving procedure might help even more people. According to the U.S. OrganProcurement and Transplantation Network, more than 120,000 patients are currently onorgan-transplant waitlists in the United States, and at least 1 in 5 patients on these waitlists diewaiting for an organ that they never receive.
       Right now, the majority of organs that could potentially be used for transplants are discarded,in large part because they can only be safely preserved for 4 to 36 hours. If only half the heartsand lungs that are discarded were successfully transplanted, the waitlists for those organs couldbe eliminated in two to three years, according to the Organ Preservation Alliance.
       No matter what methods have been developed, one possible way to save donated organs fortransplantation is to freeze them. Ice crystals that can damage cells typically form during freezing,but in prior work, researchers have found a technique known as vitrification — which involvesflooding biological specimens with antifreeze-like compounds — that could help cool down organsto stave off decay, while also preventing the formation of ice crystals.
       Unfortunately, ice crystals can also form during the reheating process. Moreover, if thawing isnot uniform across samples, fracturing or cracking may occur. Although scientists had developedmethods to safely use freezing-cold temperatures to "cryopreserve" tissues and organs, they hadnot yet developed a way to safely reheat them.
【題組】31. Which of the following is the best title for this passage?
(A) Reviving Frozen Organs: Nanotech May Pave the Way
(B) Stop Discarding Organs: New transplanting Technique
(C) More Donated Organs Are Needed to Save More Lives
(D) Big Breakthrough in Reheating Human Brain Process