Light-induced Cell Detachment Research Articles

Gr/TiO2 Films with Light-Controlled Positive/Negative Charge for Cell Harvesting Application

Light-induced cell harvest shows much potential in in vitro cell culture. In this work, a light-responsive monolayer graphene (Gr)/titanium dioxide nanodot (TN) film is designed and used for light-induced cell harvest. It is found that after 20 min of 365 nm UV or 450 nm visible light illumination, different types of cells could be detached from the surface effectively. The highest cell detachment ratio reaches about 95%. The mechanism of such a cell detachment is contributed to light illumination generates charge accumulation, which, in turn, changes the conformation of the extracellular matrix protein molecules adsorbed to a more disordered state, and eventually leads to the cells detachment. Such UV and visible light responsive Gr/TiO2 film could be a good candidate for a surface with light-induced cell detachment property.

Surface hydroxyls regulation promotes light-induced cell detachment on TiO2 nanodot films

In this work, hydrothermal treatment and ultraviolet illumination (254 nm) were utilized to regulate the surface hydroxyls of titanium dioxide (TiO2) nanodots films. The effects on light-induced cell detachment behaviors were also investigated and discussed. Scanning electron microscopy, Raman, X-ray photoelectron spectroscopy and Circular dichroism were used to characterize the surface morphology, crystalline phase, surface composition and adsorption conformation of protein molecules. It was found that a combined process of ultraviolet illumination followed by hydrothermal treatment not only promoted cells adhesion but also showed the highest efficiency in light induced cell detachment. The reason is ascribed to that such process promotes the formation of terminal hydroxyl groups in TiO2 surface, and subsequently affect the adsorption conformation of protein molecules. This study indicated that such treatment could effectively modulate the contents of surface hydroxyl groups in different states. That shows much potential in optimizing the biological performance of TiO2 based biomaterials.

TiO2/ZnO composite nanodots films and their cellular responses

In the present study, TiO2/ZnO composite nanodot films were prepared and the effects of Zn incorporation on light-induced cell detachment were investigated. The nanodots films, which were successfully synthesized by phase-separation-induced self-assembly method, were characterized on the morphology, composition, microstructure, and other properties, and evaluated on cell compatibility and cell detachment performances as well. Live-dead staining was used to study the viability of cell sheet detached by light illumination. Results shows that with the increasing of introduced Zn, the band gap widened and the absorbance in UV region increased, while the crystallinity and performance of light-induced hydrophilicity weakened. All the nanodots films showed good cell compatibility and cell detachment performance induced by light. The nanodots film which had a Zn/Ti molar ratio of 0.03 showed the highest detachment ratio of 91.0% after 20 min ultraviolet illumination. The prepared TiO2/ZnO composite nanodots films could be helpful in optimizing light-induced cell detachment behavior.

SiO2/TiO2 Nanocomposite Films on Polystyrene for Light-Induced Cell Detachment Application.

Light-induced cell detachment shows much potential in in vitro cell culture and calls for high-performance light-responsive films. In this study, a smooth and dense SiO2/TiO2 nanocomposite thin film with thickness of around 250 nm was first fabricated on H2O2 treated polystyrene (PS) substrate via a low-temperature sol-gel method. It was observed that the film could well-adhere on the PS surface and the bonding strength became increasingly high with the increase of SiO2 content. The peeling strength and shear strength reached 3.05 and 30.02 MPa, respectively. It was observed the surface of the film could transform into superhydrophilic upon 20 min illumination of ultraviolet with a wavelength of 365 nm (UV365). In cell culture, cells, i.e., NIH3T3 and MC3T3-E1 cells, cultured on SiO2/TiO2 nanocomposite film were easily detached after 10 min of UV365 illumination; the detachment rates reached 90.8% and 88.6%, respectively. Correspondingly, continuous cell sheets with good viability were also easily obtained through the same way. The present work shows that SiO2/TiO2 nanocomposite thin film could be easily prepared on polymeric surface at low temperature. The corresponding film exhibits excellent biocompatibility, high bonding strength, and good light responses. It could be a good candidate for the surface of cell culture utensils with light-induced cell detachment property.

Light-Induced Cell-Sheet Harvest on TiO2 Films Sensitized with Carbon Quantum Dots.

Invited for this month's cover is the interdisciplinary research group of Prof. Kui Cheng from Zhejiang University, China. The cover picture shows a schematic figure of carbon quantum dots incorporated as a sensitizer into TiO2 films to regulate the light-induced cell-detachment performance. Read the full text of the article at 10.1002/cplu.201600202.

Light-Induced Cell-Sheet Harvest on TiO2 Films Sensitized with Carbon Quantum Dots.

Carbon quantum dots (CQDs) have been incorporated as a sensitizer into TiO2 films to regulate the light-induced cell-detachment performance. Depending on the amount of CQDs incorporated, nanodots or porous films are obtained. It was found that the right amount of CQDs incorporation significantly improves the cell-sheet detachment efficiency, and an intact cell sheet could be obtained after merely five minutes of UV illumination (365 nm, UV365), which is much faster than that from CQDs-free TiO2 film. Furthermore, cell sheets on CQDs-sensitized TiO2 films show improved viability, and alkaline phosphatase and collagen I activity either before or after light-induced detachment. The improved cell-detachment performance is ascribed to the effective inhibition of charge recombination of the TiO2 film and the microstructure variations, which increase the negative surface potential and change the secondary structure of the adsorbed extracellular protein molecules; this results in a faster release of cells. It is suggested that the faster release reduces the possible detrimental impact on cell functions during detachment and helps in maintaining the excellent cellular activity. This study demonstrates that CQDs sensitization is an effective approach for optimizing the performance of light-induced cell-sheet harvest.

Effects of RGD immobilization on light-induced cell sheet detachment from TiO2 nanodots films

Light-induced cell detachment is reported to be a safe and effective cell sheet harvest method. In the present study, the effects of arginine–glycine–aspartic acid (RGD) immobilization on cell growth, cell sheet construction and cell harvest through light illumination are investigated. RGD was first immobilized on TiO2 nanodots films through simple physical adsorption, and then mouse pre-osteoblastic MC3T3-E1 cells were seeded on the films. It was found that RGD immobilization promoted cell adhesion and proliferation. It was also observed that cells cultured on RGD immobilized films showed relatively high level of pan-cadherin. Cells harvested with ultraviolet illumination (365nm) showed good viability on both RGD immobilized and unmodified TiO2 nanodot films. Single cell detachment assay showed that cells detached more quickly on RGD immobilized TiO2 nanodot films. That could be ascribed to the RGD release after UV365 illumination. The current study demonstrated that RGD immobilization could effectively improve both the cellular responses and light-induced cell harvest.

Improved light-induced cell detachment on rutile TiO2 nanodot films

Anatase TiO2 nanodot films have been found to be able to release cells under light illumination with excellent efficiency and safety. In the present study, we investigated the effects of rutile contents in TiO2 nanodot films on such light induced cell detachment behavior. The results showed that TiO2 nanodot films with different contents of rutile phase have been prepared successfully. The content of rutile phase increased with the increase in calcination temperature. All films possessed good cell adhesion but there was a decrease in cell proliferation with the increasing content of rutile phase. Single cell detachment assay showed that the films with high rutile contents (calcined at 900°C and 1100°C) showed better cell detachment performance. That was ascribed to the changes of the secondary structure of extracellular proteins adsorbed on the nanodot surface after ultraviolet (365nm, UV365) illumination. In addition, cell sheets detached through UV365 illumination maintained high activity and could be further used in tissue engineering. The present work showed that the existence of rutile phase is helpful in cell detachment behavior and it could be utilized to optimize light-induced cell detachment behavior. Statement of SignificanceThis work discovers that the presence of rutile phase in TiO2 nanodot films could improve the light-induced cell detachment behavior, although rutile phase is inferior to anatase phase on light induced superhydrophilicity. That strongly supported that the behaviors of adsorbed proteins are crucial in acquiring cell sheet with light illumination. In fact, the state and behavior of adsorbed protein greatly affect the interaction between biomaterials and living cells. Therefore, we consider this work is not only important in harvesting cells or cell sheets through light illumination, but also helpful in further understanding of interaction between biomaterials and cells.

The Effects of TiO2 Nanodot Films with RGD Immobilization on Light-Induced Cell Sheet Technology.

Cell sheet technology is a new strategy in tissue engineering which could be possible to implant into the body without a scaffold. In order to get an integrated cell sheet, a light-induced method via UV365 is used for cell sheet detachment from culture dishes. In this study, we investigated the possibility of cell detachment and growth efficiency on TiO2 nanodot films with RGD immobilization on light-induced cell sheet technology. Mouse calvaria-derived, preosteoblastic (MC3T3-E1) cells were cultured on TiO2 nanodot films with (TR) or without (TN) RGD immobilization. After cells were cultured with or without 5.5 mW/cm2 UV365 illumination, cell morphology, cell viability, osteogenesis related RNA and protein expression, and cell detachment ability were compared, respectively. Light-induced cell detachment was possible when cells were cultured on TR samples. Also, cells cultured on TR samples showed better cell viability, alongside higher protein and RNA expression than on TN samples. This study provides a new biomaterial for light-induced cell/cell sheet harvesting.

A facile approach to improve light induced cell sheet harvesting through nanostructure optimization

In the present study, the effects of nanostructure on the light-induced cell detachment property of anatase TiO2 films are investigated and discussed.

Effect of Pt/C addition to TiO2 films on adhesion and rapid light-induced detachment of mammalian cell cultures

Light-induced cell detachment on the substrate of TiO2 nanodots has been proved to be a safe and attractive method for cell harvesting in tissue engineering. In order to improve the cell release efficiency, bioinert platinum with excellent charge transport loading in biocompatible graphite was prepared. 20 wt.% Pt/C powder showing excellent electrical, chemical and bioactive properties was incorporated to a TiO2 system. We investigated the biocompatibility of Pt/C–TiO2 composite films with different amounts of Pt/C with C/tetrabutyl titanate molar ratio varying from 0 to 0.42. The adhesion and proliferation rates of pre-osteoblastic MC3T3-E1 cells (mouse calvaria-derived) on the films prepared with the highest C/TiO2 molar ratio are higher than that of the pure TiO2 and other films, indicating a Pt/C dose-dependent effect. It is shown that the detachment efficiency of MC3T3-E1 cells depends on Pt/C amount and UV illumination time. Moreover, films prepared with C/tetrabutyl titanate molar ratio of 0.42 showed 93% cell detachment ratio within 5 min of UV illumination, while bare TiO2 films only reached 75%, indicating an improved cell release efficiency by the incorporation of Pt/C. However, an interesting phenomenon was found that longer illumination time showed lower detachment ratios to some extent, which is contrary to our previous work. It is believed that this work presents the improved cell detachment efficiency by the incorporation of Pt/C.

Noninvasive Photodetachment of Stem Cells on Tunable Conductive Polymer Nano Thin Films: Selective Harvesting and Preserved Differentiation Capacity

Viable mesenchymal stem cells (MSCs) were efficiently and selectively harvested by near-infrared (NIR) light using the photothermal effect of a conductive polymer nano thin film. The poly(3,4-ethylenedioxy thiophene) (PEDOT)-coated cell culture surfaces were prepared via a simple and fast solution-casting polymerization (SCP) technique. The absorption of PEDOT thin films in the NIR region was effectively triggered cell harvesting upon exposure to an NIR source. By controlling the NIR absorption of the PEDOT film through electrochemical doping or growing PEDOT with different thin film thickness from 70 to 300 nm, the proliferation and harvesting of MSCs on the PEDOT surface were controlled quantitatively. This light-induced cell detachment method based on PEDOT films provides the temporal and spatial control of cell harvesting, as well as cell patterning. The harvested stem cells were found to be alive and well proliferated despite the use of temperature increase by NIR. More importantly, the harvested MSCs by this method preserved their intrinsic characteristics as well as multilineage differentiation capacities. This PEDOT surfaces could be used for repetitive culture and detachment of MSCs or for efficient selection or depletion of a specific subset from heterogeneous population during culture of various tissue-derived cells because there were no photodegradation and photobreakage in the PEDOT films by NIR exposure.

Light-induced cell detachment for cell sheet technology

The phenomenon of light-induced cell detachment is reported. Mouse calvaria-derived, pre-osteoblastic (MC3T3-E1) cells were cultured on a TiO2 nanodot-coated quartz substrate. After 20 min of UV365 illumination, over 90% of the cells would detach from the surface. Moreover, intact cell sheets could be obtained in the same way. It was found that the as-obtained cells showed good viability, and could be used for further culture processes and other applications. Also, biocompatibility and safety characterizations indicated that the use of TiO2 nanodots and UV365 illumination was safe for such cell detachment. It is suggested that adsorbed extracellular matrix proteins play key roles in developing cell sheets and ensuring biocompatibility. The present light-induced cell detachment method demonstrates a promising way for rapid cell/cell sheet harvesting.