Natural tactile sensation is complex, which involves not only contact force intensity detection but also the perception of the force direction, the surface texture, and other mechanical parameters. Nevertheless, the vast majority of the developed tactile sensors can only detect the normal force, but usually cannot resolve shear force or even distinguish the directions of the force. Here, we present a new paradigm of bioinspired tactile sensors for resolving both the intensity and the directions of mechanical stimulations via synergistic microcrack-bristle structure design and cross-shaped configuration engineering. The microcrack sensing structure gives high mechanical sensitivity to the tactile sensors, and the synergistic bristle structure further amplifies the sensitivity of the sensors. The cross-shaped configuration engineering of the synergistic microcrack-bristle structure further endows the tactile sensors with good capability to detect and distinguish the directions of the applied mechanical forces. The as-fabricated tactile sensors exhibit a high sensitivity (25.76 N
−1
), low detection limit (5.4 mN), desirable stability (over 2,500 cycles), and good capability to resolve both mechanical intensity and directional features. As promising application scenarios, surface texture recognition and biomimetic path explorations are successfully demonstrated with these tactile sensors. This newly proposed tactile sensation strategy and technology have great potential applications in ingenious tactile sensation and construction of various robotic and bionic prostheses with high operational dexterity.
OBJECTIVE To examine the effect of Pin1 on the expression and bioactivity of MMP-9 through NF-κB in human colorectal carcinoma SW480 cells. METHODS The eukaryotic expression vector of RNA interfering (shRNA) with the Pin1 gene (pGenesil-1-PIN1) was constructed in our previous experiments and was confi rmed through sequencing. Cell motility was tested through the wound healing assay and the Boyden chamber assay. The protein levels and bioactivity of MMP-9 were tested by Western blott ing and gelatin zymography in SW480 cells after transfection with pGenesil-1-PIN1 (SW480/ p-shRNA). The DNA-binding activity of NF-κB in cells transfected with pGenesil-1-PIN1 was analyzed by the electrophoretic mobility shift assay (EMSA). In addition, to determine whether NF-κB has direct interaction with the MMP-9 promoter derived from the genomic DNA of SW480 cells transfected with pGenesil-1-PIN1, oligonucleotides containing a putative NF-κB binding site were synthesized and EMSAs were performed. RESULTS The results of the Boyden chamber assay showed that cell motility was reduced from 90.2 ± 6.5 per fi eld (× 10 objective) to 49.6 ± 7.2 per field (P < 0.05, Student's t-test) for SW480 cells transfected with pGenesil-1-PIN1 (SW480/p-shRNA). Western blott ing detected low protein levels of Pin1 and MMP-9 in SW480/ p-shRNA cells. The relative protein levels of Pin1 were 0.49 ± 0.07 in SW480/p-shRNA compared with 0.94 ± 0.09 in SW480/p-Con, and MMP-9 were 0.45 ± 0.07 in SW480/p-shRNA, 0.83 ± 0.07 in SW480/p-Con (P < 0.05). The results of gelatin zymography showed that silencing Pin1 markedly reduced the bioactivity of MMP-9 in SW480 cells. EMSA results revealed low DNA-binding activity of NF-κB in SW480/p-shRNA cells compared to SW480/ p-Con cells, and that NF-κB bound directly to the oligonucleotides which contained putative NF-κB binding sites in the MMP-9 promoter derived from the genomic DNA of SW480/p-shRNA cells. CONCLUSION Inhibited Pin1 expression may contribute to the suppressive eff ect on the expression and bioactivity of MMP-9 in colon cancer SW480 cells, possibly through the transcription factor NF-κB.
Wearable
electronic sensors that can perform real-time, continuous,
and high-fidelity monitoring of diverse biophysical signals from the
human body are burgeoning and exhibit great potential to transform
traditional clinical healthcare. However, such emerging devices often
suffer from strict requirements of special precursor materials and
sophisticated fabrication procedures. Here, we present a new paradigm
of a self-powered, skin-attachable, and multifunctional sensing platform
that can be fully created just at home with daily necessities. Its
operating mechanism is based on mechanical/thermal regulation of the
potential difference output of a primary electrochemical cell. This
proposed sensing platform is totally self-powered and can be conformally
attached to the skin for continuous monitoring of both mechanical
and thermal stimulations. A wide spectrum of vital physiological signs
of the human body, including body temperature, heart/pulse rate, respiratory
rate, coughing, and body motions, can be continuously monitored and
analyzed with this home-made sensing platform. This study demonstrates
that the lab-conducted professional and expensive scientific research
can also be accomplished at home, opening up new opportunities for
home-centered healthcare in low-resource environments. Moreover, this
work can serve as a handy and cost-efficient prototype for classroom
education and clinical training purposes.
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