2010年2月4日出版的英国《自然》杂志（Nature, 2010, 463, 640-643）刊登了中国科学院化学研究所江雷院士与合作者们在蜘蛛丝集水机理上的突破性研究成果，并作为封面报道。该工作基于几年来对生物表面特殊浸润性的研究基础（Nature, 2004, 432, 36; Adv. Mater. 2002, 14, 1857-1860）和对生物表面水收集特性的探索，仔细观察自然界蜘蛛丝上微区水收集行为，发现了几十微米尺度的液滴能够在蜘蛛丝上从一个区域移到另一个区域而展示了运动的方向性，并从微纳米结构层次上揭示了其集水的“多协同效应”机制。

　　在探究中发现，筛孔蜘蛛（Uloborus Walckenaerius）的捕捉丝在遇到雾而润湿时，能由纳米细纤维组成的蓬松“Puff”和链接结构 （图1）变成周期的突起结构（称为“Spindle-knot”）和纤细的链接结构（称为“Joint”）（图2-3）。有趣的是，在Spindle-knot上形成了无序分布的纳米纤维结构（图3c），而在Joint上则形成了有序排列的纳米纤维结构（图3e）。这些结构特性在Spindle-knot和Joint之间形成了表面能量梯度，同时由于曲率梯度还产生拉普拉斯（Laplace）压差 (图4)。正是这些微观多结构的耦合，这两个梯度的力协同地作用到小尺度液滴上，使蜘蛛丝能够达成一个连续不断的水凝结，并完成凝结液滴从Joint到Spindle-knot的方向的传输。结果是较大的水滴能够被快速而效率地收集，并稳定地挂在蜘蛛丝上，因而产生超强的水收集能力。这种微纳米结构的多协同力效应，已在初步构建的仿生人造类蜘蛛丝纤维上，实现了小尺度液滴的方向性驱动（图5）。

　　该工作将预示可以解决以往在小尺度液滴驱动上的瓶颈问题。例如，以往研究中，当表面能梯度或者拉普拉斯压差被分别地设计到一个表面上时，较大尺度（几百微米尺度以上）的液滴是容易地被驱动的。但是随着液滴尺度的降低，接触角粘滞将严重阻碍液滴的行为，从而使液滴（less than 200 mm）的移动变得相当困难。通过揭示蜘蛛丝的水收集机制和初步的仿生研究，在对小尺度液滴的方向性驱动上打开了一个新的开端。

　　这个蜘蛛丝的集水“多协同效应”机制，将启发科学家们设计微流体中的新型的微流控表面；设计大规模的人造纤维网以收集空气、雾气中的水，来供给水源缺乏地区人们的需求；设计精美的催化材料，通过微观结构效应，驱动不同成分的化学物质聚集，促进快速而有效的反应；此外，还可以设计纤维网状材料，以用到工业加工和生产过程中的浮质过滤等等。

　　该项研究工作得到了尊龙凯时重大研究计划、重大国际合作基金、面上项目基金等资助。

《自然》期刊封皮：Caught in the web ¾ the structural flip that allows spiders' silk to collect water

图1 蜘蛛的干的捕捉丝 a）由周期的蓬松“Puff”和链接“Joint”组成，分布在两条主轴纤维上；b）蓬松部分Puff由纳米细丝组成。 图2 水凝结时捕捉丝外形结构的改变, Puff 变成梭形的结 “Spindle-knot”（a-d）和凝结滴的方向收集行为（e-f）；g-i）在单个spindle-knot上凝结滴的方向性行为。图3 外形改变的蜘蛛丝的微观结构，b-c） Spindle-knot上具有无序的纳米细丝多孔结构；d-e）Joint上具有有序的纳米细丝阵列纤维结构。图4 凝结液滴方向性驱动的微观机制图解，a）无序的纳米细丝结构形成不连续的三相接触线（TCL）而有序地纳米细丝结构形成连续的TCL，b）表面能量梯度和Laplace压强差的协同驱动液滴的方向移动。图5 仿生构建了类蜘蛛丝结构，实现了液滴的方向性移动。

　　该工作出版之时，即刻迎来了世界各大媒体的关注：

　　《自然》新闻网 https://www.nature.com/news/2010/100203/full/news.2010.47.html

　　英国广播公司新闻网 https://news.bbc.co.uk/2/hi/science/nature/8496559.stm

　　材料研究协会https://www.mrs.org/s_mrs/sec.asp?CID=1920&DID=84063，

　　物理学会https://Physicsworld.com

　　物理https://www.physorg.com

　　皇家化学科学学会https://www.rsc.org/chemistryworld/News/2010/February/03021003.asp

　　俄罗斯科学网https://www.infox.ru/themes/science/  等等

　　其中，世界范围的蜘蛛研究专家、动物学家、分子生物学家、微结构物理专家、生物工程专家分别对该工作的意义给予了高度的评价。

注：

--"It is impressive that they were able to produce an analogue of wetted [spider] thread that duplicated the properties that they observed," says spider silk expert Brent Opell of Virginia Tech in Blacksburg（布莱克斯堡，维吉尼亚工学院）.

--Brent Opell, a spider expert at Virginia Tech in Virginia, US, is equally cautious about the results, although he says the experimental work is sound. 'The implication that [capture] threads have evolved to harvest moisture is not the view of most arachnologists,' he says. 'But the study is well executed and the performance of the threads is fully described and mathematically modelled.'

--"The authors of this paper are studying an artefact," says zoologist and spider-silk expert Fritz Vollrath of the University of Oxford, UK, "（英国牛津大学） which is still interesting although it has no biological function".

--But Fritz Vollrath, who studies spider silk at Oxford University in the UK, disagrees with Jiang's theory. He thinks spider silk has to be dry to function. 'If I am correct, then the authors are studying an artefact, which is still interesting, although it has no biological function,' says Vollrath. 'If, on the other hand, the authors are correct and in these specific silks, wetting is used - presumably to enhance capture efficiency - then the team would have uncovered an unexpected twist in the story, which would draw a lot of attention and further research.'

--Dr Randolph Lewis, a molecular biologist from the University of Wyoming, US（美国，怀俄明州大学）, who studies spider silk said: "The most interesting feature of this study is that the effect is totally due to the fibres themselves."

He pointed out that spider silk has properties that are "unmatched by any manmade material".

"If we can learn how to match those properties we would have a 'green' material with superior mechanical properties for a wide variety of applications," he added.

--Mato Knez at the Max Planck Institute of Microstructure Physics （麦克斯普朗克微结构物理研究院）, who is also interested in industrial applications inspired by spider webs, believes that it could be a tactic to protect the web. "If the water is distributed along the silk as film, this might lead to destruction. However, by allowing the droplets to grow until reaching a critical size they will presumably fall from the silk," he says.

--Andrew Martin, a bioengineer at Bremen University in Germany （德国不来梅大学）, is doubtful that this technology could be useful on a large industrial scale, but he envisages smaller-scale application. "The directionality of water collection might be useful in any rheological or microfluidic process."