어류는 일상에서 쉽게 소비되지만, 식품 및 양식 분야가 준비(Preparation), 통조림 제조(Canning), 염장(Salting) 등 과정에서 엄청난 양의 어류 비늘 폐기물(Fish Scale Waste)을 발생시킨다는 사실은 잘 알려져 있지 않다. 매립지에 어류 비늘 폐기물을 처리하는 것은 심각한 환경오염 문제를 일으킬 수 있어 이를 기능성 물질로 전환함으로써 환경 영향을 줄이고 경제적 이익을 창출하는 데 도움이 될 수 있다. 

싱가포르 국립대학교(National University of Singapore, NUS) 물리학부 연구진은 오염물질인 로다민 B(Rhodamine B)를 물에서 효과적으로 제거하는 바이오 흡착제로 기능하고, 어류 비늘 폐기물을 정보 암호화를 위한 물질로 활용하는 새로운 방법을 개발했다. 

소 총 하우(Sow Chorng Haur) NUS 물리학과 교수가 이끄는 연구팀은 어류 비늘을 가열하면 섬유나 종이, 페인트 및 물흐름 추적제에 사용되는 분홍색 염료인 수질 오염물질 로다민 B에 적합한 흡착제로 변형된다는 사실을 밝혀냈다. 로다민 B은 암과 간부전 등 잠재적인 건강 위험뿐 아니라 해양 생태계에 대한 위협과 밀접한 연관이 있다.

연구진은 희미한 '로얄 블루 형광물질(Royal Blue Fluorescence)'과 비교해, 열처리된 어류 비늘이 자외선(UV) 아래에서 선명한 청록색 빛(Cyan Glow)을 방출하는 것을 발견했다. 이러한 특성을 통해 어류 비늘은 미세하고 거시적인 텍스트 및 이미지를 전달하는 천연물질로 활용될 수 있다.

소 총 하우 교수는 "전 세계 인구가 증가하고 자원이 더욱 제한됨에 따라 지속 가능성은 폐기물 재이용의 필요성을 강조한다"며  "폐기물을 재평가함으로써 이전에는 간과된 재료에서 매혹적인 특성과 다기능성을 발견할 수 있었다"고 말했다. 

그는 이어 "전 세계적으로 매년 약 720만~1천200만 톤의 어류 폐기물이 발생할 것으로 예상되는데, 이를 통해 어류 비늘 폐기물은 업사이클링을 위한 풍부한 자원으로 활용될 수 있다"고 덧붙였다.

연구진은 샤론 임 샤오다이(Sharon Lim Xiaodai) NUS 물리학부 박사, 장 쩡(Zhang Zheng) 과학기술연구청(Agency of Science, Technology and Research) 박사, 말콤 소 먀오 정(Mr. Malcolm Sow Miao Geng) NUS 수학과학고등학교 교사로 구성됐다. 이 연구 결과는 2023년 11월 24일 『네이처 커뮤니케이션스(Nature Communications)』에 게재됐다. 

[원문보기]

Upcycling fish scales for water pollution control and encryption

Fish is commonly consumed but many may not be aware that the food and aquaculture sectors generate a huge amount of fish scale waste from processes such as preparation, canning, filleting, salting and smoking. Disposal of fish scale waste in landfills may cause serious environmental pollution problems. Therefore, converting fish scale waste into functional materials could help to reduce environmental impact and generate economic benefits.

Contributing to this effort, physicists from the National University of Singapore (NUS) have developed a novel method of repurposing fish scale waste to act as a bio-adsorbant to effectively remove the pollutant Rhodamine B from water, and a material for information encryption.

A research team, led by Professor Sow Chorng Haur from the NUS Department of Physics, discovered that heating fish scales at an optimal temperature transformed them to become suitable adsorbents for water pollutant Rhodamine B, a common pink dye used in textiles, paper, paints and water flow tracing agents. Rhodamine B is associated with potential health risks such as cancer and liver failure, and threats to marine ecosystems.

The scientists also found that the heat-treated fish scales emitted a vibrant cyan glow, compared to a dim royal blue fluorescence when they were untreated, under ultraviolet (UV) light. This characteristic can be harnessed to utilise fish scales as a natural material capable of transmitting micro and macroscopic text and imagery.

“As the global population grows and resources become more limited, sustainability involves greater emphasis on reusing waste materials. Globally, an estimated 7.2-12 million tons of fish waste is projected to be discarded yearly. This makes fish scale waste an abundant resource for upcycling. By re-evaluating waste streams, fascinating properties and multifunctionalities can be discovered in materials that may have been overlooked previously,” said Prof Sow.

The research team also comprised Dr Sharon Lim Xiaodai from the NUS Department of Physics, Dr Zhang Zheng from the Agency of Science, Technology and Research, and Mr Malcolm Sow Miao Geng from the NUS High School of Math and Science. The findings were published in the journal Nature Communications on 16 October 2023.

Giving new life to fish scale waste

Fish scales primarily consist of interlacing collagen, a protein known for maintaining a youthful appearance, and hydroxyapatite, a mineral found in bones and teeth. Due to the good biocompatibility of these two compounds, different methods have been used to extract them for further development into fluorescence labels which help detect biomolecules in research. However, these processes often require significant amounts of time, energy, and chemical resources. Enhancing the fluorescence of fish scales through a more direct and efficient method would improve cost-effectiveness.

With the researchers’ facile heating method, the fish scales undergo both chemical and physical changes. Long chains of collagen are broken down into smaller segments that emit blue light under UV excitation. Simultaneously, atom arrangement is altered which creates surface and internal pores that transform fluorescence properties and enhance pollutant adsorption.

When in contact with Rhodamine B, the heat-treated fish scales effectively removed 91 per cent of of the pollutant within a short 10-minute contact time. Fish scales contaminated with Rhodamine B can be reused through a simple sonication process, enhancing the sustainability of the material. With just a single thermal annealing step required, this innovative technique is more cost, energy and time efficient than using other inexpensive biomass such as activated carbon white sugar which needs to go through multiple steps of chemical treatment, washing and thermal annealing in order to remove Rhodamine B.

The fluorescent properties of the heat-treated fish scales under different types of light can also be harnessed for steganographic purposes. Scales can be heated in bulk on a hotplate and arranged to convey a message, or laser-engraved with text and images on a microscopic scale. These hidden messages can be revealed under UV light. Heat-treated fish scales which have adsorbed Rhodamine B also glow orange under green light excitation, compared to the same heat-treated fish scales without Rhodamine B that display a very dim blue fluorescence under the same light. This presents another option for steganographic pattern design.

Next steps

Looking ahead, the research team will look into developing economical and readily accessible Rhodamine B test kits for use in outfield detection using heat-treated fish scales. The approach will help minimise the risk of Rhodamine B consumption and exposure by communities relying on natural water bodies, and outfield scientists transporting contaminated water sources.

Further research is also planned to explore whether the heat-treated fish scales can adsorb other toxic chemicals.

[출처=싱가포르 국립대학교((National University of Singapore)(https://news.nus.edu.sg/upcycling-fish-scales-pollution-control-encryption/) / 2024년 2월 26일]

[논문출처= 『네이처 커뮤니케이션스(Nature Communications)』(https://www.nature.com/articles/s41467-023-42080-1) / 2023년 11월 24일

[번역 = 방호윤 기자]