Tag Archives: Fei Yan

Biosynthetic melanin nanoparticles enabled by genetically engineered bacterium

A January 13, 2023 news item on phys.org announces research into genetically engineering bacteria so they produce melanin nanoparticles, i.e., biosynthetic melanin nanoparticles, Note: Links have been removed,

Photothermal therapy (PTT) has attracted considerable attention for the treatment of tumors because it is minimally invasive and has spatiotemporal selectivity.

Melanin is a kind of multifunctional pigment found widely in mammals, plants and microbes, with great prospects as a PTT agent for cancer treatment. Unfortunately, commercially available melanin is mainly obtained by chemical synthesis or extraction from sepia, which hinders its large-scale production and causes some potential safety hazards.

Recently, a research team led by Prof. Yan Fei from the Shenzhen Institute of Advanced Technology (SIAT) of the Chinese Academy of Sciences, together with Prof. Lin Jing from Shenzhen University and Prof. Xu Xiaohong from Guangdong Medical University, heterologously expressed a tyrosinase gene in Escherichia coli to synthesize melanin nanoparticles under mild and environmentally friendly conditions.

Caption: Schematic illustration of biosynthetic melanin nanoparticles for photoacoustic imaging-guided photothermal therapy. Credit: SIAT [Shenzhen Institute of Advanced Technology]

A January 13, 2023 Chinese Academy of Sciences press release (also on EurekAlert but published January 12, 2023), which originated the news item, provides a little more detail about the research,

The biosynthetic melanin nanoparticles exhibited excellent biocompatibility, good stability, and negligible toxicity. “They had strong absorption in the near-infrared region and higher photothermal conversion efficiency (48.9%) than chemically synthesized melanin-like polydopamine nanoparticles under an 808-nm laser irradiation,” said Prof. YAN.

The researchers further evaluated the photoacoustic imaging performance and antitumor efficacy of biosynthetic melanin nanoparticles. The results showed that the biosynthetic melanin nanoparticles had excellent photoacoustic imaging performance and could be used for photoacoustic imaging-guided photothermal therapy in vivo

“Our study provided an alternative approach to synthesize PTT agents with broad application potential in the diagnosis and treatment of cancer,” said Prof. YAN.

Here’s a link to and a citation for the paper,

Biosynthesis of Melanin Nanoparticles for Photoacoustic Imaging Guided Photothermal Therapy by Meijun Fu, Yuping Yang, Zhaomeng Zhang, Yaling He, Yuanyuan Wang, Chenxing Liu, Xiaohong Xu, Jing Lin, Fei Yan. Small DOI: https://doi.org/10.1002/smll.202205343 First published: 29 December 2022

This paper is behind a paywall.

Ferroelectric switching in the lung, heart, and arteries

A June 23, 2014 University of Washington (state) news release (also on EurekAlert) describes how the human body (and other biological tissue) is capable of generating ferroelectricity,

University of Washington researchers have shown that a favorable electrical property is present in a type of protein found in organs that repeatedly stretch and retract, such as the lungs, heart and arteries. These findings are the first that clearly track this phenomenon, called ferroelectricity, occurring at the molecular level in biological tissues.

The news release gives a brief description of ferroelectricity and describes the research team’s latest work with biological tissues,

Ferroelectricity is a response to an electric field in which a molecule switches from having a positive to a negative charge. This switching process in synthetic materials serves as a way to power computer memory chips, display screens and sensors. This property only recently has been discovered in animal tissues and researchers think it may help build and support healthy connective tissues in mammals.

A research team led by Li first discovered ferroelectric properties in biological tissues in 2012, then in 2013 found that glucose can suppress this property in the body’s connective tissues, wherever the protein elastin is present. But while ferroelectricity is a proven entity in synthetic materials and has long been thought to be important in biological functions, its actual existence in biology hasn’t been firmly established.

This study proves that ferroelectric switching happens in the biological protein elastin. When the researchers looked at the base structures within the protein, they saw similar behavior to the unit cells of solid-state materials, where ferroelectricity is well understood.

“When we looked at the smallest structural unit of the biological tissue and how it was organized into a larger protein fiber, we then were able to see similarities to the classic ferroelectric model found in solids,” Li said.

The researchers wanted to establish a more concrete, precise way of verifying ferroelectricity in biological tissues. They used small samples of elastin taken from a pig’s aorta and poled the tissues using an electric field at high temperatures. They then measured the current with the poling field removed and found that the current switched direction when the poling electric field was switched, a sign of ferroelectricity.

They did the same thing at room temperature using a laser as the heat source, and the current also switched directions.

Then, the researchers tested for this behavior on the smallest-possible unit of elastin, called tropoelastin, and again observed the phenomenon. They concluded that this switching property is “intrinsic” to the molecular make-up of elastin.

The next step is to understand the biological and physiological significance of this property, Li said. One hypothesis is that if ferroelectricity helps elastin stay flexible and functional in the body, a lack of it could directly affect the hardening of arteries.

“We may be able to use this as a very sensitive technique to detect the initiation of the hardening process at a very early stage when no other imaging technique will be able to see it,” Li said.

The team also is looking at whether this property plays a role in normal biological functions, perhaps in regulating the growth of tissue.

Co-authors are Pradeep Sharma at the University of Houston, Yanhang Zhang at Boston University, and collaborators at Nanjing University and the Chinese Academy of Sciences.

Here’s a link to and a citation for the research paper,

Ferroelectric switching of elastin by Yuanming Liu, Hong-Ling Cai, Matthew Zelisko, Yunjie Wang, Jinglan Sun, Fei Yan, Feiyue Ma, Peiqi Wang, Qian Nataly Chen, Hairong Zheng, Xiangjian Meng, Pradeep Sharma, Yanhang Zhang, and Jiangyu Li. Proceedings of the National Academy of Sciences (PNAS) doi: 10.1073/pnas.1402909111

This paper is behind a paywall.

I think this is a new practice. There is a paragraph on the significance of this work (follow the link to the paper),

Ferroelectricity has long been speculated to have important biological functions, although its very existence in biology has never been firmly established. Here, we present, to our knowledge, the first macroscopic observation of ferroelectric switching in a biological system, and we elucidate the origin and mechanism underpinning ferroelectric switching of elastin. It is discovered that the polarization in elastin is intrinsic at the monomer level, analogous to the unit cell level polarization in classical perovskite ferroelectrics. Our findings settle a long-standing question on ferroelectric switching in biology and establish ferroelectricity as an important biophysical property of proteins. We believe this is a critical first step toward resolving its physiological significance and pathological implications.