A mechanics model is developed for the contact radius of stamps with pyramid tips in transfer printing.This is important to the realization of reversible control of adhesion,which has many important applications,such ...A mechanics model is developed for the contact radius of stamps with pyramid tips in transfer printing.This is important to the realization of reversible control of adhesion,which has many important applications,such as climbing robots,medical tapes,and transfer printing of electronics.The contact radius is shown to scale linearly with the work of adhesion between the stamp and the contacting surface,and inversely with the plane-strain modulus of the stamp. It also depends on the cone angle and tip radius of the stamp,but is essentially independent of details of the tip geometry.展开更多
With practical interest in the future applications of next-generation electronic devices,it is imperative to develop new conductive interconnecting materials appropriate for modern electronic devices to replace tradit...With practical interest in the future applications of next-generation electronic devices,it is imperative to develop new conductive interconnecting materials appropriate for modern electronic devices to replace traditional rigid solder tin and silver paste of high melting temperature or corrosive solvent requirements.Herein,we design highly stretchable shape memory self-soldering conductive(SMSC)tape with reversible adhesion switched by temperature,which is composed of silver particles encapsulated by shape memory polymer.SMSC tape has perfect shape and conductivity memory property and anti-fatigue ability even under the strain of 90%.It also exhibits an initial conductivity of 2772 S cm^(−1) and a maximum tensile strain of~100%.The maximum conductivity could be increased to 5446 S cm^(−1) by decreasing the strain to 17%.Meanwhile,SMSC tape can easily realize a heating induced reversible strong-to-weak adhe-sion transition for self-soldering circuit.The combination of stable conductivity,excellent shape memory performance,and temperature-switching reversible adhesion enables SMSC tape to serve two functions of electrode and solder simultaneously.This provides a new way for conductive interconnecting materials to meet requirements of modern electronic devices in the future.展开更多
Hydrogels with multifunctionalities,including sufficient bonding strength,injectability and self-healing capacity,responsive-adhesive ability,fault-tolerant and repeated tissue adhesion,are urgently demanded for invas...Hydrogels with multifunctionalities,including sufficient bonding strength,injectability and self-healing capacity,responsive-adhesive ability,fault-tolerant and repeated tissue adhesion,are urgently demanded for invasive wound closure and wound healing.Motivated by the adhesive mechanism of mussel and brown algae,bioinspired dynamic bonds cross-linked multifunctional hydrogel adhesive is designed based on sodium alginate(SA),gelatin(GT)and protocatechualdehyde,with ferric ions added,for sutureless post-wound-closure.The dynamic hydrogel cross-linked through Schiff base bond,catechol-Fe coordinate bond and the strong interaction between GT with temperature-dependent phase transition and SA,endows the resulting hydrogel with sufficient mechanical and adhesive strength for efficient wound closure,injectability and self-healing capacity,and repeated closure of reopened wounds.Moreover,the temperature-dependent adhesive properties endowed mispositioning hydrogel to be removed/repositioned,which is conducive for the fault-tolerant adhesion of the hydrogel adhesives during surgery.Besides,the hydrogels present good biocompatibility,near-infrared-assisted photothermal antibacterial activity,antioxidation and repeated thermo-responsive reversible adhesion and good hemostatic effect.The in vivo incision closure evaluation demonstrated their capability to promote the post-wound-closure and wound healing of the incisions,indicating that the developed reversible adhesive hydrogel dressing could serve as versatile tissue sealant.展开更多
Transfer printing based on switchable adhesive that heterogeneously integrates materials is essential to develop novel electronic systems,such as flexible electronics and micro LED displays.Here,we report a robust des...Transfer printing based on switchable adhesive that heterogeneously integrates materials is essential to develop novel electronic systems,such as flexible electronics and micro LED displays.Here,we report a robust design of a thermal actuated switchable dry adhesive,which features a stiff sphere embedded in a thermally responsive shape memory polymer(SMP)substrate and encapsulated by an elastomeric membrane.This construct bypasses the unfavorable micro-and nano-fabrication processes and yields an adhesion switchability of over1000 by combining the peel-rate dependent effect of the elastomeric membrane and the thermal actuation of the sub-surface embedded stiff sphere.Experimental and numerical studies reveal the underlying thermal actuated mechanism and provide insights into the design and operation of the switchable adhesive.Demonstrations of this concept in stamps for transfer printing of fragile objects,such as silicon wafers,silicon chips,and inorganic micro-LED chips,onto challenging non-adhesive surfaces illustrate its potential in heterogeneous material integration applications,such as flexible electronics manufacturing and deterministic assembly.展开更多
旨在研究犬腺病毒-2型(canine adenovirus type 2,CAV-2)作为溶瘤病毒的潜力并进一步探索精子黏附因子(SPAM1)协同CAV-2重塑肿瘤微环境在肿瘤免疫治疗中的应用价值。本研究以P15A-CAV-2反向遗传操作平台为基础,使用RED/ET同源重组系统...旨在研究犬腺病毒-2型(canine adenovirus type 2,CAV-2)作为溶瘤病毒的潜力并进一步探索精子黏附因子(SPAM1)协同CAV-2重塑肿瘤微环境在肿瘤免疫治疗中的应用价值。本研究以P15A-CAV-2反向遗传操作平台为基础,使用RED/ET同源重组系统构建携带SPAM1外源基因的中间载体,使用中间载体将CAV-2骨架载体E3区域缺失并替换SPAM1外源基因表达盒。再利用合成引物敲除kmccdB反向筛选表达盒构建P15A-CAV-2-mCMV-SPAM1-SV40 polyA感染性克隆质粒并在MDCK-E1A细胞系中拯救重组溶瘤病毒,对重组病毒体外溶瘤效应进行验证。根据测序与酶切验证结果证明,本研究成功构建并拯救出稳定表达外源基因SPAM1的重组溶瘤病毒1株;IFA试验证明,重组毒株能够高水平稳定表达外源基因且外源蛋白具有可弥散分布于细胞间的特点。缺失E3区域表达外源基因SPAM1的重组溶瘤病毒通过光镜观察和CCK8检测发现具有对犬癌细胞系A72强烈的杀伤效应。综上,本研究成功构建1株具有良好溶瘤效应的重组CAV-2,为后续应用于宠物肿瘤治疗奠定了基础。展开更多
Protecting the skin from UV light irradiation in wet and underwater environments is challenging due to the weak adhesion of existing sunscreen materials but highly desired.Herein we report a polyethyleneimine/thioctic...Protecting the skin from UV light irradiation in wet and underwater environments is challenging due to the weak adhesion of existing sunscreen materials but highly desired.Herein we report a polyethyleneimine/thioctic acid/titanium dioxide(PEI/TA/TiO_(2))coacervate-derived hydrogel with robust,asymmetric,and reversible wet bioadhesion and effective UV-light-shielding ability.The PEI/TA/TiO_(2)complex coacervate can be easily obtained by mixing a PEI solution and TA/TiO_(2)powder.The fluid PEI/TA/TiO_(2)coacervate deposited on wet skin can spread into surface irregularities and subsequently transform into a hydrogel with increased cohesion,thereby establishing interdigitated contact and adhesion between the bottom surface and skin.Meanwhile,the functional groups between the skin and hydrogel can form physical interactions to further enhance bioadhesion,whereas the limited movement of amine and carboxyl groups on the top hydrogel surface leads to low adhesion.Therefore,the coacervate-derived hydrogel exhibits asymmetric adhesiveness on the bottom and top surfaces.Moreover,the PEI/TA/TiO_(2)hydrogel formed on the skin could be easily removed using a NaHCO3 aqueous solution without inflicting damage.More importantly,the PEI/TA/TiO_(2)hydrogel can function as an effective sunscreen to block UV light and prevent UV-induced MMP-9 overexpression,inflammation,and DNA damage in animal skin.The advantages of PEI/TA/TiO_(2)coacervate-derived hydrogels include robust,asymmetric,and reversible wet bioadhesion,effective UV light-shielding ability,excellent biocompatibility,and easy preparation and usage,making them a promising bioadhesive to protect the skin from UV light-associated damage in wet and underwater environments.展开更多
A material-structure integrated design method is proposed in this paper,with which micropillar and microwedge arrayed surfaces are fabricated based on a novel nanoparticlereinforced silicone rubber composite(NRSRC)wit...A material-structure integrated design method is proposed in this paper,with which micropillar and microwedge arrayed surfaces are fabricated based on a novel nanoparticlereinforced silicone rubber composite(NRSRC)with high mechanical strength and strong surface adhesion.It is found that the micropillar-arrayed surface and the microwedgearrayed surface show a normal adhesive strength of 50.9 kPa and a shear adhesive strength of 137.3 kPa,respectively,which are much higher than those of previously reported adhesive surfaces made by pure soft polymers.Furthermore,the micro-wedgearrayed surface shows not only strong and stable adhe-sion on rough and smooth substrates but also an obvious anisotropy in the adhesion property.The latter consequently leads to an easy control of the attachment/detachment switch,which is evidenced by a mechanical gripper with a microwedged surface.Therefore,firmly picking up and easily releasing a heavy glass plate can be realized.All these results demonstrate the apparent advantages of the present compo-sitebased fibrillar surfaces in achieving reliable and reversible adhesion and should have promising applications for manufac-turing advanced adhesive devices,such as mechanical fixtures,portable climbing equipment and space robots.展开更多
BACKGROUND Although minimally invasive surgery is becoming more commonly applied for ileostomy reversal(IR),there have been relatively few studies of IR for patients with Crohn's disease(CD).It is therefore import...BACKGROUND Although minimally invasive surgery is becoming more commonly applied for ileostomy reversal(IR),there have been relatively few studies of IR for patients with Crohn's disease(CD).It is therefore important to evaluate the potential benefits and risks of laparoscopy for patients with CD.AIM To compare the safety,feasibility,and short-term and long-term outcomes of laparoscopic IR(LIR)vs open IR(OIR)for the treatment of CD.METHODS The baseline characteristics,operative data,and short-term(30-d)and long-term outcomes of patients with CD who underwent LIR and OIR at our institution between January 2017 and January 2020 were retrieved from an electronic database and retrospectively reviewed.RESULTS Of the 60 patients enrolled in this study,LIR was performed for 48 and OIR for 12.There were no statistically significant differences in baseline characteristics,operation time,intraoperative blood loss,days to flatus and soft diet,postoperative complications,hospitalization time,readmission rate within 30 d,length of hospitalization,hospitalization costs,or reoperation rate after IR between the two groups.However,patients in the LIR group more frequently required lysis of adhesions as compared to those in the OIR group(87.5%vs 41.7%,respectively,P<0.05).Notably,following exclusion of patients who underwent enterectomy plus IR,OIR was more advantageous in terms of postoperative recovery of gastrointestinal function and hospitalization costs.CONCLUSION The safety and feasibility of LIR for the treatment of CD are comparable to those of OIR with no increase in intraoperative or postoperative complications.展开更多
Bio-inspired reversible adhesion has significant potential in many fields requiring flexible grasping and manipulation,such as precision manufacturing,flexible electronics,and intelligent robotics.Despite extensive ef...Bio-inspired reversible adhesion has significant potential in many fields requiring flexible grasping and manipulation,such as precision manufacturing,flexible electronics,and intelligent robotics.Despite extensive efforts for adhesive synthesis with a high adhesion strength at the interface,an effective strategy to actively tune the adhesion capacity between a strong attachment and an easy detachment spanning a wide range of scales has been lagged.Herein,we report a novel soft-hard-soft sandwiched composite design to achieve a stable,repeatable,and reversible strong adhesion with an easily scalable performance for a large area ranging from~1.5 to 150 cm2 and a high load ranging from~20 to 700 N.Theoretical studies indicate that this design can enhance the uniform loading for attachment by restraining the lateral shrinkage in the natural state,while facilitate a flexible peeling for detachment by causing stress concentration in the bending state,yielding an adhesion switching ratio of~54 and a switching time of less than~0.2 s.This design is further integrated into versatile grippers,climbing robots,and human climbing grippers,demonstrating its robust scalability for a reversible strong adhesion.This biomimetic design bridges microscopic interfacial interactions with macroscopic controllable applications,providing a universal and feasible paradigm for adhesion design and control.展开更多
文摘A mechanics model is developed for the contact radius of stamps with pyramid tips in transfer printing.This is important to the realization of reversible control of adhesion,which has many important applications,such as climbing robots,medical tapes,and transfer printing of electronics.The contact radius is shown to scale linearly with the work of adhesion between the stamp and the contacting surface,and inversely with the plane-strain modulus of the stamp. It also depends on the cone angle and tip radius of the stamp,but is essentially independent of details of the tip geometry.
基金This work is supported by National Key R&D Program of China(Grant No.2020YFA0711500)the National Natural Science Fund of China(51973095&52011540401).
文摘With practical interest in the future applications of next-generation electronic devices,it is imperative to develop new conductive interconnecting materials appropriate for modern electronic devices to replace traditional rigid solder tin and silver paste of high melting temperature or corrosive solvent requirements.Herein,we design highly stretchable shape memory self-soldering conductive(SMSC)tape with reversible adhesion switched by temperature,which is composed of silver particles encapsulated by shape memory polymer.SMSC tape has perfect shape and conductivity memory property and anti-fatigue ability even under the strain of 90%.It also exhibits an initial conductivity of 2772 S cm^(−1) and a maximum tensile strain of~100%.The maximum conductivity could be increased to 5446 S cm^(−1) by decreasing the strain to 17%.Meanwhile,SMSC tape can easily realize a heating induced reversible strong-to-weak adhe-sion transition for self-soldering circuit.The combination of stable conductivity,excellent shape memory performance,and temperature-switching reversible adhesion enables SMSC tape to serve two functions of electrode and solder simultaneously.This provides a new way for conductive interconnecting materials to meet requirements of modern electronic devices in the future.
基金supported by the National Natural Science Foundation of China (No. 51973172)Natural Science Foundation of Shaanxi Province (Nos. 2020JC-03 and 2019TD-020)+2 种基金the State Key Laboratory for Mechanical Behavior of Materials,the World-Class Universities (Disciplines) and Characteristic Development Guidance Funds for the Central UniversitiesFundamental Research Funds for the Central Universitiesthe Opening Project of the Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research,College of Stomatology,Xi’an Jiaotong University (No. 2019LHM-KFKT008).
文摘Hydrogels with multifunctionalities,including sufficient bonding strength,injectability and self-healing capacity,responsive-adhesive ability,fault-tolerant and repeated tissue adhesion,are urgently demanded for invasive wound closure and wound healing.Motivated by the adhesive mechanism of mussel and brown algae,bioinspired dynamic bonds cross-linked multifunctional hydrogel adhesive is designed based on sodium alginate(SA),gelatin(GT)and protocatechualdehyde,with ferric ions added,for sutureless post-wound-closure.The dynamic hydrogel cross-linked through Schiff base bond,catechol-Fe coordinate bond and the strong interaction between GT with temperature-dependent phase transition and SA,endows the resulting hydrogel with sufficient mechanical and adhesive strength for efficient wound closure,injectability and self-healing capacity,and repeated closure of reopened wounds.Moreover,the temperature-dependent adhesive properties endowed mispositioning hydrogel to be removed/repositioned,which is conducive for the fault-tolerant adhesion of the hydrogel adhesives during surgery.Besides,the hydrogels present good biocompatibility,near-infrared-assisted photothermal antibacterial activity,antioxidation and repeated thermo-responsive reversible adhesion and good hemostatic effect.The in vivo incision closure evaluation demonstrated their capability to promote the post-wound-closure and wound healing of the incisions,indicating that the developed reversible adhesive hydrogel dressing could serve as versatile tissue sealant.
基金financial support from the National Natural Science Foundation of China(Grant Nos.11872331 and U20A6001)the Zhejiang University K P Chao’s High Technology Development Foundation。
文摘Transfer printing based on switchable adhesive that heterogeneously integrates materials is essential to develop novel electronic systems,such as flexible electronics and micro LED displays.Here,we report a robust design of a thermal actuated switchable dry adhesive,which features a stiff sphere embedded in a thermally responsive shape memory polymer(SMP)substrate and encapsulated by an elastomeric membrane.This construct bypasses the unfavorable micro-and nano-fabrication processes and yields an adhesion switchability of over1000 by combining the peel-rate dependent effect of the elastomeric membrane and the thermal actuation of the sub-surface embedded stiff sphere.Experimental and numerical studies reveal the underlying thermal actuated mechanism and provide insights into the design and operation of the switchable adhesive.Demonstrations of this concept in stamps for transfer printing of fragile objects,such as silicon wafers,silicon chips,and inorganic micro-LED chips,onto challenging non-adhesive surfaces illustrate its potential in heterogeneous material integration applications,such as flexible electronics manufacturing and deterministic assembly.
文摘旨在研究犬腺病毒-2型(canine adenovirus type 2,CAV-2)作为溶瘤病毒的潜力并进一步探索精子黏附因子(SPAM1)协同CAV-2重塑肿瘤微环境在肿瘤免疫治疗中的应用价值。本研究以P15A-CAV-2反向遗传操作平台为基础,使用RED/ET同源重组系统构建携带SPAM1外源基因的中间载体,使用中间载体将CAV-2骨架载体E3区域缺失并替换SPAM1外源基因表达盒。再利用合成引物敲除kmccdB反向筛选表达盒构建P15A-CAV-2-mCMV-SPAM1-SV40 polyA感染性克隆质粒并在MDCK-E1A细胞系中拯救重组溶瘤病毒,对重组病毒体外溶瘤效应进行验证。根据测序与酶切验证结果证明,本研究成功构建并拯救出稳定表达外源基因SPAM1的重组溶瘤病毒1株;IFA试验证明,重组毒株能够高水平稳定表达外源基因且外源蛋白具有可弥散分布于细胞间的特点。缺失E3区域表达外源基因SPAM1的重组溶瘤病毒通过光镜观察和CCK8检测发现具有对犬癌细胞系A72强烈的杀伤效应。综上,本研究成功构建1株具有良好溶瘤效应的重组CAV-2,为后续应用于宠物肿瘤治疗奠定了基础。
基金the National Key Research and Development Program(2022YFB3804403)the Collaborative Research Fund from the Research Grants Council of Hong Kong(Project No.C5044-21G)+1 种基金the Research Grants Council of the Hong Kong Special Administration Region(project no.GRF/14202920,GRF/14204618,GRF/14108720,T13-402/17-N and AoE/M-402/20)National Natural Science Foundation of China(22205264).
文摘Protecting the skin from UV light irradiation in wet and underwater environments is challenging due to the weak adhesion of existing sunscreen materials but highly desired.Herein we report a polyethyleneimine/thioctic acid/titanium dioxide(PEI/TA/TiO_(2))coacervate-derived hydrogel with robust,asymmetric,and reversible wet bioadhesion and effective UV-light-shielding ability.The PEI/TA/TiO_(2)complex coacervate can be easily obtained by mixing a PEI solution and TA/TiO_(2)powder.The fluid PEI/TA/TiO_(2)coacervate deposited on wet skin can spread into surface irregularities and subsequently transform into a hydrogel with increased cohesion,thereby establishing interdigitated contact and adhesion between the bottom surface and skin.Meanwhile,the functional groups between the skin and hydrogel can form physical interactions to further enhance bioadhesion,whereas the limited movement of amine and carboxyl groups on the top hydrogel surface leads to low adhesion.Therefore,the coacervate-derived hydrogel exhibits asymmetric adhesiveness on the bottom and top surfaces.Moreover,the PEI/TA/TiO_(2)hydrogel formed on the skin could be easily removed using a NaHCO3 aqueous solution without inflicting damage.More importantly,the PEI/TA/TiO_(2)hydrogel can function as an effective sunscreen to block UV light and prevent UV-induced MMP-9 overexpression,inflammation,and DNA damage in animal skin.The advantages of PEI/TA/TiO_(2)coacervate-derived hydrogels include robust,asymmetric,and reversible wet bioadhesion,effective UV light-shielding ability,excellent biocompatibility,and easy preparation and usage,making them a promising bioadhesive to protect the skin from UV light-associated damage in wet and underwater environments.
基金NSFC through Grants(No.12032004,No.12293000,No.12293002,No.12272043)Natural Science Foundation of Henan(No.202300410088)as well as Innovation Demonstration Project of Henan(No.201111211400).
文摘A material-structure integrated design method is proposed in this paper,with which micropillar and microwedge arrayed surfaces are fabricated based on a novel nanoparticlereinforced silicone rubber composite(NRSRC)with high mechanical strength and strong surface adhesion.It is found that the micropillar-arrayed surface and the microwedgearrayed surface show a normal adhesive strength of 50.9 kPa and a shear adhesive strength of 137.3 kPa,respectively,which are much higher than those of previously reported adhesive surfaces made by pure soft polymers.Furthermore,the micro-wedgearrayed surface shows not only strong and stable adhe-sion on rough and smooth substrates but also an obvious anisotropy in the adhesion property.The latter consequently leads to an easy control of the attachment/detachment switch,which is evidenced by a mechanical gripper with a microwedged surface.Therefore,firmly picking up and easily releasing a heavy glass plate can be realized.All these results demonstrate the apparent advantages of the present compo-sitebased fibrillar surfaces in achieving reliable and reversible adhesion and should have promising applications for manufac-turing advanced adhesive devices,such as mechanical fixtures,portable climbing equipment and space robots.
基金The study protocol was approved by the Ethics Committee of the Shanghai Tenth People’s Hospital Affiliated to the Tongji University School of Medicine(approval No.21K53).
文摘BACKGROUND Although minimally invasive surgery is becoming more commonly applied for ileostomy reversal(IR),there have been relatively few studies of IR for patients with Crohn's disease(CD).It is therefore important to evaluate the potential benefits and risks of laparoscopy for patients with CD.AIM To compare the safety,feasibility,and short-term and long-term outcomes of laparoscopic IR(LIR)vs open IR(OIR)for the treatment of CD.METHODS The baseline characteristics,operative data,and short-term(30-d)and long-term outcomes of patients with CD who underwent LIR and OIR at our institution between January 2017 and January 2020 were retrieved from an electronic database and retrospectively reviewed.RESULTS Of the 60 patients enrolled in this study,LIR was performed for 48 and OIR for 12.There were no statistically significant differences in baseline characteristics,operation time,intraoperative blood loss,days to flatus and soft diet,postoperative complications,hospitalization time,readmission rate within 30 d,length of hospitalization,hospitalization costs,or reoperation rate after IR between the two groups.However,patients in the LIR group more frequently required lysis of adhesions as compared to those in the OIR group(87.5%vs 41.7%,respectively,P<0.05).Notably,following exclusion of patients who underwent enterectomy plus IR,OIR was more advantageous in terms of postoperative recovery of gastrointestinal function and hospitalization costs.CONCLUSION The safety and feasibility of LIR for the treatment of CD are comparable to those of OIR with no increase in intraoperative or postoperative complications.
基金This work was supported by the National Natural Science Foundation of China(Grant No.51425502).
文摘Bio-inspired reversible adhesion has significant potential in many fields requiring flexible grasping and manipulation,such as precision manufacturing,flexible electronics,and intelligent robotics.Despite extensive efforts for adhesive synthesis with a high adhesion strength at the interface,an effective strategy to actively tune the adhesion capacity between a strong attachment and an easy detachment spanning a wide range of scales has been lagged.Herein,we report a novel soft-hard-soft sandwiched composite design to achieve a stable,repeatable,and reversible strong adhesion with an easily scalable performance for a large area ranging from~1.5 to 150 cm2 and a high load ranging from~20 to 700 N.Theoretical studies indicate that this design can enhance the uniform loading for attachment by restraining the lateral shrinkage in the natural state,while facilitate a flexible peeling for detachment by causing stress concentration in the bending state,yielding an adhesion switching ratio of~54 and a switching time of less than~0.2 s.This design is further integrated into versatile grippers,climbing robots,and human climbing grippers,demonstrating its robust scalability for a reversible strong adhesion.This biomimetic design bridges microscopic interfacial interactions with macroscopic controllable applications,providing a universal and feasible paradigm for adhesion design and control.
