Cellulose sutures step toward clinic: Green threads promise to mend, then melt away
Nanofiber and oxidized derivatives hit 50 % strength loss within a week, meeting the global benchmark for absorbable stitches
image: Nanofiber and oxidized derivatives hit 50 % strength loss within a week, meeting the global benchmark for absorbable stitches
Credit: Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
Surgeons sew an estimated 300 million knots every year, almost all of them tied with plastics derived from oil. A new review released on 15 December in the Journal of Bioresources and Bioproducts argues that the next generation of stitches may come from the most abundant biopolymer on Earth: cellulose.
By tracing surgical thread from ancient Egyptian linen to today’s nanofiber laboratories, researchers from the Chinese Academy of Sciences and Tarbiat Modares University show that cotton, ramie and wood pulp can be re-engineered to disappear inside the body almost as fast as gut sutures yet retain the predictability that modern operations demand.
The key advance is chemical oxidation. When standard cellulose is treated with TEMPO or periodate, carboxyl groups swell the fiber, allowing water and enzymes to unzip the polymer chains. The resulting oxidized regenerated cellulose (ORC) loses 61 % of its tensile strength in 14 days and is fully absorbed within a month, the review finds. That degradation curve satisfies the 60-day benchmark set by the United States Pharmacopeia for “absorbable” sutures, a category previously dominated by polyglycolic acid (PGLA) and polydioxanone.
Mechanical performance, long the Achilles heel of bio-based threads, now rivals synthetic standards. Wet-spun cellulose nanofibrils aligned by flow-focusing reach 1 570 MPa—three times the strength of tendon tissue—while twisted bacterial-nanocellulose yarns combine 90 MPa tensile stress with 290 % elongation, enough to stretch rather than cut swollen wound edges.
Biocompatibility data are equally upbeat. In rat-skin trials, CNF-chitosan filaments triggered 30 % less expression of the inflammatory marker IL-6 than commercial silk and accelerated angiogenesis within seven days. Embedding ciprofloxacin or benzalkonium bromide during interfacial polyelectrolyte complexation produced zones of inhibition against Escherichia coli and Staphylococcus aureus that remained clear for 72 hours, a potential hedge against surgical-site infections that claim millions of extra hospital days each year.
Still, challenges persist. Spinning speeds for IPC fibers hover below 0.5 m min⁻¹—two orders of magnitude slower than high-throughput viscose lines—and the low viscosity of 0.1–0.5 % nanocellulose suspensions can yield uneven diameters. Regulatory agencies will also demand long-term toxicology of degradation products such as glucuronic acid and short-chain oligosaccharides.
Yet the environmental calculus is compelling. Life-cycle assessments cited in the review estimate that cellulose sutures could cut greenhouse-gas emissions by 60 % compared with PGLA, while diverting agricultural waste from burning. With China’s National Natural Science Foundation and Iran National Science Foundation backing scale-up projects, the authors predict first-in-human trials of braided CNF sutures within three years.
If those trials succeed, the operating room’s most carbon-intensive disposable may soon grow on trees—and vanish just as gracefully inside the human body.