Aim To evaluate the interactive effects of different self- adhesive resin cements and tribochemical treatment on bond strength to zirconia. Methodology The following self-adhesive resin cements for bonding two zirconi...Aim To evaluate the interactive effects of different self- adhesive resin cements and tribochemical treatment on bond strength to zirconia. Methodology The following self-adhesive resin cements for bonding two zirconia blocks were evaluated: Maxcem (MA), Smartcem (SM), Rely X Unicem Aplicap (UN), Breeze (BR), Biscem (BI), Set (SE), and Clearfil SA luting (CL). The specimens were grouped according to conditioning as follows: Group 1, polishing with 600 grit polishing paper; Group 2, silica coating with 110 μm Al2O3 particles which modified with silica; and, Group 3, tribochemical treatment - silica coating + silanization. Specimens were stored in distilled water at 37℃ for 24 hours before testing shear bond strength. Results Silica coating and tribochemical treatment significantly increased the bond strength of the MA, UN, BR, B1, SE and CL to zirconia compared to #600 polishing. For both #600 polished and silica coating treatments, MDP- containing self-adhesive resin cement CL had the highest bond strengths to zirconia. Conclusion Applying silica coating and tribochemical treatment improved the bond strength of self-adhesive resin cement to zirconia, especially for CL.展开更多
With the advent of the 5G era and the rise of the Internet of Things,various sensors have received unprecedented attention,especially wearable and stretchable sensors in the healthcare field.Here,a stretchable,self-he...With the advent of the 5G era and the rise of the Internet of Things,various sensors have received unprecedented attention,especially wearable and stretchable sensors in the healthcare field.Here,a stretchable,self-healable,self-adhesive,and room-temperature oxygen sensor with excellent repeatability,a full concentration detection range(0-100%),low theoretical limit of detection(5.7 ppm),high sensitivity(0.2%/ppm),good linearity,excellent temperature,and humidity tolerances is fabricated by using polyacrylamide-chitosan(PAM-CS)double network(DN)organohydrogel as a novel transducing material.The PAM-CS DN organohydrogel is transformed from the PAM-CS composite hydrogel using a facile soaking and solvent replacement strategy.Compared with the pristine hydrogel,the DN organohydrogel displays greatly enhanced mechanical strength,moisture retention,freezing resistance,and sensitivity to oxygen.Notably,applying the tensile strain improves both the sensitivity and response speed of the organohydrogel-based oxygen sensor.Furthermore,the response to the same concentration of oxygen before and after self-healing is basically the same.Importantly,we propose an electrochemical reaction mechanism to explain the positive current shift of the oxygen sensor and corroborate this sensing mechanism through rationally designed experiments.The organohydrogel oxygen sensor is used to monitor human respiration in real-time,verifying the feasibility of its practical application.This work provides ideas for fabricating more stretchable,self-healable,self-adhesive,and high-performance gas sensors using ion-conducting organohydrogels.展开更多
The effects of different post-space pretreatments on the retentive force of fiber posts cemented with a self-adhesive resin cement were investigated. Twenty-eight single-canal premolars were obturated by Resilon using...The effects of different post-space pretreatments on the retentive force of fiber posts cemented with a self-adhesive resin cement were investigated. Twenty-eight single-canal premolars were obturated by Resilon using warm vertical compaction and treated with distilled water, 2.5% NaOCl, 17% EDTA and 2.5% NaOCI; or 17% EDTA, 2.5% NaOCI, and ultrasonic agitation (U/E/N treatment). Subsequently, radicular dentin surfaces were observed under scanning electron microscopy (SEM). RelyX Fiber Posts were cemented in the treated canals by using RelyX U100, and thin-slice push-out test and SEM observation of coronal and apical regions of the specimens were performed. Data were analyzed using two-way ANOVA and Tukey's HSD post- hoc tests, and the percentage of failure type was calculated. Ultrasonic/EDTA/NaOC1 irrigation showed the maximum effectiveness in removing the smear layer and debris on the dentin surface. The apical bond strength of the experimental groups was significantly higher than that of the control group (P〈 0.05). Adhesive failure between cement and dentin was the most common mode of failure. No obvious RDIZ or resin tag was detected. Chemical irrigants facilitated the bonding of these fiber posts, and ultrasonic activation improved retention. Future studies should evaluate the effectiveness of irrigation on fiber post push-out strength in fatigue cycling condition.展开更多
A new family of transparent,biocompatible,self-adhesive,and self-healing elastomer has been developed by a convenient and efficient one-pot reaction between poly(acrylic acid)(PAA)and hydroxyl-terminated polydimethyls...A new family of transparent,biocompatible,self-adhesive,and self-healing elastomer has been developed by a convenient and efficient one-pot reaction between poly(acrylic acid)(PAA)and hydroxyl-terminated polydimethylsiloxane(PDMSOH).The condensation reaction between PAA and PDMS-OH has been confirmed by attenuated total reflection Fourier transform infrared(ATR-FTIR)spectra.The prepared PAA-PDMS elastomers possess robust mechanical strength and strong adhesiveness to human skin,and they have fast self-healing ability at room temperature(in^10 s with the efficiency of 98%).Specifically,strain sensors were fabricated by assembling PAA-PDMS as packaging layers and polyetherimide-reduced graphene oxide(PEI-rGO)as strain-sensing layers.The PAA-PDMS/PEI-rGO sensors are stably and reliably responsive to slight physical deformations,and they can be attached onto skin directly to monitor the body’s motions.Meanwhile,strain sensors can self-heal quickly and completely,and they can be reused for the motion detecting after shallowly scratching the surface.This work provides new opportunities to manufacture high performance self-adhesive and self-healing materials.展开更多
The complexity of application environment stimulates the development of wearable devices based on functional hydrogels.Among all the promising performances,self-healing and self-adhesion properties are ideal for hydro...The complexity of application environment stimulates the development of wearable devices based on functional hydrogels.Among all the promising performances,self-healing and self-adhesion properties are ideal for hydrogel sensors,which can guarantee good accuracy,comfort and long service life.However,it is still a challenge to achieve simultaneous self-healing and self-adhesion in different environments(in the air,underwater and at low temperatures).Herein,a feasible new strategy was successfully carried out to prepare a starch-based composite conductive organohydrogel based on the reversible borate ester bonds formed by complexing starch/polyvinyl alcohol(PVA)/tea polyphenol(TP)with borax,and multiple hydrogen-bond interactions among PVA,starch,TP and ethylene glycol(EG).Silver nanoparticles(Ag-NPs),reduced and stabilized by TP,and MWCNTs(multi-walled carbon nanotubes)were introduced into the cross-linking networks to endow the resulting PBSTCE organohydrogel with considerable antibacterial property and conductivity,respectively.The organohydrogel possessed rapid self-healing(HE(self-healing efficiency)=96.07%in 90 s,both in the air and underwater,also at-20℃),considerable self-adhesion(both in the air and underwater,also at-20℃),remarkable stretchability(814%of elongation),anti-freezing(-20℃)and moisture-retention abilities,antibacterial activity,sensitive pH/sugar-responsiveness,and plasticity.The strain sensor formed by the PBSTCE organohydrogel can not only effectively record large-scale human motions(e.g.finger/wrist/elbow bending,walking,etc.),but also accurately capture subtle motion changes(e.g.breathing,chewing,swallowing,speaking,smiling and frowning).Moreover,the self-healed organohydrogel sensor also exhibited almost invariable mechanical,electrical and sensing behaviors.This work demonstrates a feasible strategy to construct multifunctional starch-based organohy-drogels,and promotes their efficient,stable and eco-friendly application as flexible wearable devices.展开更多
Wound management is a crucial measure for skin wound healing and is significantly important to maintaining the integrity of skins and their functions.Electrical stimulation at the wound site is a compelling strategy f...Wound management is a crucial measure for skin wound healing and is significantly important to maintaining the integrity of skins and their functions.Electrical stimulation at the wound site is a compelling strategy for skin wound repair.However,there has been an urgent need for wearable and point-of-care electrical stimulation devices that have self-adhesive and mechanical properties comparable to wound tissue.Herein,we develop a bioinspired hybrid patch with self-adhesive and piezoelectric nanogenerator(HPSP)for promoting skin wound healing,which is composed of a mussel-inspired hydrogel matrix and a piezoelectric nanogenerator based on aligned electrospun poly(vinylidene fluoride)nanofibers.The device with optimized modulus and permeability for skin wear can self-adhere to the wound site and locally produce a dynamic voltage caused by motion.We show that the HPSP not only promotes fibroblast proliferation and migration in vitro,but also effectively facilitates the collagen deposition,angiogenesis,and re-epithelialization in vivo with the increased expressions of crucial growth factors.The HPSP reduces the wound closure time of full-thickness skin defects by about 1/3,greatly accelerating the healing process.This patch can serve as wearable and real-time electrical stimulation devices,potentially useful in clinical applications of skin wound healing.展开更多
Limited surface lubrication and bacterial biofilm formation pose great challenges to biomedical implants.Although hydrophilic lubricated coatings and bacterial resistance coatings have been reported,the harsh and tedi...Limited surface lubrication and bacterial biofilm formation pose great challenges to biomedical implants.Although hydrophilic lubricated coatings and bacterial resistance coatings have been reported,the harsh and tedious synthesis greatly compromises their application,and more importantly,the bacterial resistance property has seldom been investigated in combination with the lubrication property.In this study,bioinspired by the performances of mussel and articular cartilage,we successfully synthesized self-adhesive lubricated coating and simultaneously achieved optimal lubrication and bacterial resistance properties.Additionally,we reported the mechanism of bacterial resistance on the nanoscale by studying the adhesion interactions between biomimetic coating and hydrophilic/hydrophobic tip or living bacteria via atomic force microscopy.In summary,the self-adhesive lubricated coating can effectively enhance lubrication and bacterial resistance performances based on hydration lubrication and hydration repulsion,and represent a universal and facial strategy for surface functionalization of biomedical implants.展开更多
文摘Aim To evaluate the interactive effects of different self- adhesive resin cements and tribochemical treatment on bond strength to zirconia. Methodology The following self-adhesive resin cements for bonding two zirconia blocks were evaluated: Maxcem (MA), Smartcem (SM), Rely X Unicem Aplicap (UN), Breeze (BR), Biscem (BI), Set (SE), and Clearfil SA luting (CL). The specimens were grouped according to conditioning as follows: Group 1, polishing with 600 grit polishing paper; Group 2, silica coating with 110 μm Al2O3 particles which modified with silica; and, Group 3, tribochemical treatment - silica coating + silanization. Specimens were stored in distilled water at 37℃ for 24 hours before testing shear bond strength. Results Silica coating and tribochemical treatment significantly increased the bond strength of the MA, UN, BR, B1, SE and CL to zirconia compared to #600 polishing. For both #600 polished and silica coating treatments, MDP- containing self-adhesive resin cement CL had the highest bond strengths to zirconia. Conclusion Applying silica coating and tribochemical treatment improved the bond strength of self-adhesive resin cement to zirconia, especially for CL.
基金support from the National Natural Science Foundation of China(61801525)the Guangdong Basic and Applied Basic Research Foundation(2020A1515010693)+1 种基金the Guangdong Natural Science Funds Grant(2018A030313400),the Science and Technology Program of Guangzhou(201904010456)the Fundamental Research Funds for the Central Universities,Sun Yat-sen University(2021qntd09).
文摘With the advent of the 5G era and the rise of the Internet of Things,various sensors have received unprecedented attention,especially wearable and stretchable sensors in the healthcare field.Here,a stretchable,self-healable,self-adhesive,and room-temperature oxygen sensor with excellent repeatability,a full concentration detection range(0-100%),low theoretical limit of detection(5.7 ppm),high sensitivity(0.2%/ppm),good linearity,excellent temperature,and humidity tolerances is fabricated by using polyacrylamide-chitosan(PAM-CS)double network(DN)organohydrogel as a novel transducing material.The PAM-CS DN organohydrogel is transformed from the PAM-CS composite hydrogel using a facile soaking and solvent replacement strategy.Compared with the pristine hydrogel,the DN organohydrogel displays greatly enhanced mechanical strength,moisture retention,freezing resistance,and sensitivity to oxygen.Notably,applying the tensile strain improves both the sensitivity and response speed of the organohydrogel-based oxygen sensor.Furthermore,the response to the same concentration of oxygen before and after self-healing is basically the same.Importantly,we propose an electrochemical reaction mechanism to explain the positive current shift of the oxygen sensor and corroborate this sensing mechanism through rationally designed experiments.The organohydrogel oxygen sensor is used to monitor human respiration in real-time,verifying the feasibility of its practical application.This work provides ideas for fabricating more stretchable,self-healable,self-adhesive,and high-performance gas sensors using ion-conducting organohydrogels.
基金Funded by the National Natural Science Foundation of China(No.H1408)
文摘The effects of different post-space pretreatments on the retentive force of fiber posts cemented with a self-adhesive resin cement were investigated. Twenty-eight single-canal premolars were obturated by Resilon using warm vertical compaction and treated with distilled water, 2.5% NaOCl, 17% EDTA and 2.5% NaOCI; or 17% EDTA, 2.5% NaOCI, and ultrasonic agitation (U/E/N treatment). Subsequently, radicular dentin surfaces were observed under scanning electron microscopy (SEM). RelyX Fiber Posts were cemented in the treated canals by using RelyX U100, and thin-slice push-out test and SEM observation of coronal and apical regions of the specimens were performed. Data were analyzed using two-way ANOVA and Tukey's HSD post- hoc tests, and the percentage of failure type was calculated. Ultrasonic/EDTA/NaOC1 irrigation showed the maximum effectiveness in removing the smear layer and debris on the dentin surface. The apical bond strength of the experimental groups was significantly higher than that of the control group (P〈 0.05). Adhesive failure between cement and dentin was the most common mode of failure. No obvious RDIZ or resin tag was detected. Chemical irrigants facilitated the bonding of these fiber posts, and ultrasonic activation improved retention. Future studies should evaluate the effectiveness of irrigation on fiber post push-out strength in fatigue cycling condition.
基金supported by the National Science Funds for Excellent Young Scholars of China (Grant No. 61822106)National Science Funds for Creative Research Groups of China (Grant No. 61421002)+1 种基金Natural Science Foundation of China (Grant No. 61671115)Opening Project of State Key Laboratory of Polymer Materials Engineering (Sichuan University) (Grant No. sklpme 2018-4-28)
文摘A new family of transparent,biocompatible,self-adhesive,and self-healing elastomer has been developed by a convenient and efficient one-pot reaction between poly(acrylic acid)(PAA)and hydroxyl-terminated polydimethylsiloxane(PDMSOH).The condensation reaction between PAA and PDMS-OH has been confirmed by attenuated total reflection Fourier transform infrared(ATR-FTIR)spectra.The prepared PAA-PDMS elastomers possess robust mechanical strength and strong adhesiveness to human skin,and they have fast self-healing ability at room temperature(in^10 s with the efficiency of 98%).Specifically,strain sensors were fabricated by assembling PAA-PDMS as packaging layers and polyetherimide-reduced graphene oxide(PEI-rGO)as strain-sensing layers.The PAA-PDMS/PEI-rGO sensors are stably and reliably responsive to slight physical deformations,and they can be attached onto skin directly to monitor the body’s motions.Meanwhile,strain sensors can self-heal quickly and completely,and they can be reused for the motion detecting after shallowly scratching the surface.This work provides new opportunities to manufacture high performance self-adhesive and self-healing materials.
基金This work is financed by the National Natural Science Founda-tion of China(No.21978180).We appreciate the valuable help of Dr.Jinwei Zhang from the College of Biomass Science and Engineering of Sichuan University and Hui Wang from the Analytical&Testing Center of Sichuan University.We thank eceshi(www.eceshi.com)for the great help in SEM analysis.
文摘The complexity of application environment stimulates the development of wearable devices based on functional hydrogels.Among all the promising performances,self-healing and self-adhesion properties are ideal for hydrogel sensors,which can guarantee good accuracy,comfort and long service life.However,it is still a challenge to achieve simultaneous self-healing and self-adhesion in different environments(in the air,underwater and at low temperatures).Herein,a feasible new strategy was successfully carried out to prepare a starch-based composite conductive organohydrogel based on the reversible borate ester bonds formed by complexing starch/polyvinyl alcohol(PVA)/tea polyphenol(TP)with borax,and multiple hydrogen-bond interactions among PVA,starch,TP and ethylene glycol(EG).Silver nanoparticles(Ag-NPs),reduced and stabilized by TP,and MWCNTs(multi-walled carbon nanotubes)were introduced into the cross-linking networks to endow the resulting PBSTCE organohydrogel with considerable antibacterial property and conductivity,respectively.The organohydrogel possessed rapid self-healing(HE(self-healing efficiency)=96.07%in 90 s,both in the air and underwater,also at-20℃),considerable self-adhesion(both in the air and underwater,also at-20℃),remarkable stretchability(814%of elongation),anti-freezing(-20℃)and moisture-retention abilities,antibacterial activity,sensitive pH/sugar-responsiveness,and plasticity.The strain sensor formed by the PBSTCE organohydrogel can not only effectively record large-scale human motions(e.g.finger/wrist/elbow bending,walking,etc.),but also accurately capture subtle motion changes(e.g.breathing,chewing,swallowing,speaking,smiling and frowning).Moreover,the self-healed organohydrogel sensor also exhibited almost invariable mechanical,electrical and sensing behaviors.This work demonstrates a feasible strategy to construct multifunctional starch-based organohy-drogels,and promotes their efficient,stable and eco-friendly application as flexible wearable devices.
基金We thank the funding support from the National Natural Science Foundation of China(Nos.51973075 and 51525302)Program for HUST Academic Frontier Youth Team(2015-01)The authors thank HUST Analytical and Testing Center for their supports on the facilities.
文摘Wound management is a crucial measure for skin wound healing and is significantly important to maintaining the integrity of skins and their functions.Electrical stimulation at the wound site is a compelling strategy for skin wound repair.However,there has been an urgent need for wearable and point-of-care electrical stimulation devices that have self-adhesive and mechanical properties comparable to wound tissue.Herein,we develop a bioinspired hybrid patch with self-adhesive and piezoelectric nanogenerator(HPSP)for promoting skin wound healing,which is composed of a mussel-inspired hydrogel matrix and a piezoelectric nanogenerator based on aligned electrospun poly(vinylidene fluoride)nanofibers.The device with optimized modulus and permeability for skin wear can self-adhere to the wound site and locally produce a dynamic voltage caused by motion.We show that the HPSP not only promotes fibroblast proliferation and migration in vitro,but also effectively facilitates the collagen deposition,angiogenesis,and re-epithelialization in vivo with the increased expressions of crucial growth factors.The HPSP reduces the wound closure time of full-thickness skin defects by about 1/3,greatly accelerating the healing process.This patch can serve as wearable and real-time electrical stimulation devices,potentially useful in clinical applications of skin wound healing.
基金supported by National Natural Science Foundation of China(52022043)Tsinghua University Initiative Scientific Research Program(20197050026)+2 种基金Precision Medicine Foundation,Tsinghua University,China(10001020120)Capital’s Funds for Health Improvement and Research(2020-2Z-40810)Research Fund of State Key Laboratory of Tribology,Tsinghua University,China(SKLT2020C11).
文摘Limited surface lubrication and bacterial biofilm formation pose great challenges to biomedical implants.Although hydrophilic lubricated coatings and bacterial resistance coatings have been reported,the harsh and tedious synthesis greatly compromises their application,and more importantly,the bacterial resistance property has seldom been investigated in combination with the lubrication property.In this study,bioinspired by the performances of mussel and articular cartilage,we successfully synthesized self-adhesive lubricated coating and simultaneously achieved optimal lubrication and bacterial resistance properties.Additionally,we reported the mechanism of bacterial resistance on the nanoscale by studying the adhesion interactions between biomimetic coating and hydrophilic/hydrophobic tip or living bacteria via atomic force microscopy.In summary,the self-adhesive lubricated coating can effectively enhance lubrication and bacterial resistance performances based on hydration lubrication and hydration repulsion,and represent a universal and facial strategy for surface functionalization of biomedical implants.
基金supported by the National Natural Science Foundation of China (51873024)the Science and Technology Department of Jilin Province (20200708102YY and 20190201234JC)