Novel Egg White Hydrogel Fabrication And Versatile Applications

Hydrogels which possess 3D crosslinking network,adjustable physicochemical performances,and stimulus-responsive capability have attracted massive interests in bioengineering,flexible bioelectronics interfaces or electronic skin,and stimuli-responsive hydrogels et al.However,the universal applications of hydrogels are limited by complicated synthesis process,complex chemical reactions and limited responsive sensitivity.Nature is the mother of innovations,with the understanding of nature,hydrogels' fabrication commences to mimic the sophisticated structures to capture advanced functions,such as self-healing and adaptable mechanics,which are essential factors for species' survival and evolution under dynamic environments.Currently,material advancing urges complexed and sophisticated material designs,as well as advanced manufacturing progressing methods.Three dimensions printing(3D printing)technique,linked with computer-aided manufacturing,creates program-controlled and intricate 3D scaffolds with high histo-architectural fidelity,which could not only meet the requirements for sophisticated material fabrication but also provide the possibility of large-scale automated manufacturing with good control and high precision.Shear-thinning is an indispensable property for 3D printable hydrogels.Generally,the shear-thinning and mechanical properties of bio-ink can be tuned by conjunction with nanoclay,ions solution or supramolecular;however,the introduction of additives or heating may induce potential unpredictable biological effects.Recently,the natural materials have attracted a great deal of interest and are well researched by materials scientists as the substitutes of synthesized chemicals because of their remarkable similarities with natural ECM and biological performance.For instance,gelatin,chitosan,dopamine,silk protein,polysaccharides,and polypeptides have been widely employed to achieve the aforementioned applications.Continuous efforts down these ways desire materials with much greener processing,lower cost,easier handling and simpler fabrication process for scaled-up industrial uses.Despite egg white(EW)has been widely investigated in areas of food or nutrition science,only a few literatures have appeared in potential practical applications.Nevertheless,the formation of real physical hydrogel of EW used in biomaterial field without complex procedures was never reported.The aim of present study was to show the potential value of EW and a simple method to form EW hydrogel exhibiting numerous excellent properties.Developed herein is a novel protein gel-EW hydrogel-as an injectable,shear-thinning,self-healing,super-stretchable/compressive,and 3D printable physical protein hydrogel obtained through a facile and rapid process using only sodium hydroxide(NaOH)treatment without any other harmful reagent or potential toxin;more interestingly,Dulbecco's Modified Eagle Medium(DMEM)and/or secondary various valent cation as crosslinking agents rather than heating and tricky chemical reactions endow the primary hydrogel stronger and flexible mechanical properties to satisfy different applications.Further direct 3D printability of the EW hydrogel at room temperature without any additives or heating,complex structure fabrication are identified.A 3D printed EW hydrogel incorporated with conductive carbon nanotube(CNT)for body motions detection and a distant sensor for index finger flexion was tested,good compatibility with conductive nanomaterials can expand the EW hydrogel to a wide range of nanocomposites applications from biological application of tissue engineering and drug delivery,to nanoelectronic biosensors and even potential future applications of smart biological machines.In addition,based on the entire difference of swelling ratio after secondary crosslinking and aforementioned mechanical properties,we developed a novel gradient tailoring humidity-responsive EW actuator which exhibits high sensitivity to water gradient.Combined with 4D printing technique,this hydrogel may lead to great promise for the actuators applications.