The zwitterionic phospholipid polymer poly(2-methacryloyloxyethyl phosphorylcholine-
-
-butyl methacrylate) (PMB) is amphiphilic copolymer, and it has been reported to directly penetrate cell ...membranes and have good cytocompatibility. Conventional PMBs are linear-type random copolymers that are polymerized by a free radical polymerization technique. In contrast, star-shaped polymers, or simple branched-type polymers, have unique properties compared to the linear types, for example, a viscosity based on the effect of the excluded volume. In this study, a branched architecture was introduced into a PMB molecular structure, and a 4-armed star-shaped PMB (4armPMB) was synthesized by an atom transfer radical polymerization (ATRP) technique known as living radical polymerization. Linear-type PMB was also synthesized using ATRP. The effects of the polymer architecture on cytotoxicity and cellular uptake were investigated. Both 4armPMB and LinearPMB were successfully synthesized, and these polymers were verified to be water soluble. Pyrene fluorescence in the polymer solution indicated that the architecture had no effect on the behavior of the polymer aggregates. In addition, these polymers caused no cytotoxicity or cell membrane damage. The 4armPMB and LinearPMB penetrated into the cells after a short incubation period, with similar rates. In contrast, the 4armPMB showed a quicker back-diffusion from the cells than that of LinearPMB. The 4armPMB showed fast cellular internalization and exiting behaviors.
Bioengineering with utilization of cells as one of the components of devices has been expected to advance developments of medical and pharmaceutical technologies. When cells are engineered, it is ...important to establish means for maintaining the activity of the cells, enhancing cell functions, and controlling cell responses. This review summarizes researches for cell encapsulation using synthetic phospholipid polymers composed of 2-methacryloyloxyethyl phosphorylcholine unit, which make hydrogel spontaneously in a cell culture environment and then cells are preserved in situ. The phospholipid polymer hydrogels show no adverse effects on the cell culture process and the mechanical properties of the hydrogels can regulate for controlling the function of cells. It also introduces molecular designs that can be easily recovered from the hydrogel matrix after the encapsulated cells have differentiated. Furthermore, the application of these hydrogels to a microdevice also describes advanced utilization of cultured cells. Phospholipid polymer hydrogels can exhibit its function even when they are applied in vivo, and as one application, introduces the prevention of adhesion with other tissues in the tissue healing process. That is, the potential application of the phospholipid polymer hydrogels in cell engineering are described.
2-Methacryloyloxyethyl phosphorylcholine (MPC) is methacrylate bearing a phosphorylcholine group in the side chain. The phosphorylcholine group generates several unique properties arising from its ...zwitterionic structure, consisting of a phosphate anion and a trimethylammonium cation. Despite these charged groups, the total electrical charge of the species is zero because of the formation of an inner salt. The polymerization of MPC proceeds both conventional and living radical polymerizations. And, using these method, the corresponding polymer can be obtained efficiently. The product, poly(MPC), is soluble in aqueous media, even if the ionic strength of the solution is high, such as in the presence of 5.0 mol/L NaCl. The polymer does not show any surface active properties, even when the polymer concentration is greater than 1.0 g/dL. Hydration of poly(MPC) mainly occurs by hydrophobic hydration of the three methyl groups in the trimethylammonium group. Thus, this hydration induces an increase in a clathrate cage structure of surrounding water molecules, i.e. an ice-like water state is formed. Because of this unique hydration, poly(MPC) cannot make strong interactions with proteins and cells. Some biomedical applications have used poly(MPC) as a protein and solid-surface modification agents.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
In soybean, lodging is sometimes caused by strong winds and rains, resulting in a decrease in yield and quality. Technical measures against lodging include “pinching”, in which the main stem is ...pruned when excessive growth is expected. However, there can be a decrease in yield when pinching is undertaken when the risk of lodging is relatively low. Therefore, it is important that pinching is performed after the future risk of lodging has been determined. The lodging angle at the full maturity stage (R8) can be explained using a multiple regression model with main stem elongation from the sixth leaf stage (V6) to the blooming stage (R1) and main stem length at the full seed stage (R6) as the explanatory variables. The objective of this study was to develop an areal lodging prediction method by combining a main stem elongation model with areal main stem length estimation using UAV remote sensing. The main stem elongation model from emergence to R1 was a logistic regression formula with the temperature and daylight hours functions f (Ti, Di) as the explanatory variables. The main stem elongation model from R1 to the peak main stem length was a linear regression formula with the main stem length of R1 as the explanatory variable. The model that synthesized these two regression formulas were used as the main stem elongation model from emergence to R8. The accuracy of the main stem elongation model was tested on the test data, and the average RMSE was 5.3. For the areal main stem length estimation by UAV remote sensing, we proposed a soil-adjusted vegetation index (SAVIvc) that takes vegetation cover into account. SAVIvc was more accurate in estimating the main stem length than the previously reported vegetation index (R2 = 0.78, p < 0.001). The main stem length estimated by the main stem elongation model combined with SAVIvc was substituted into a multiple regression model of lodging angle to test the accuracy of the areal lodging prediction method. The method was able to predict lodging angles with an accuracy of RMSE = 8.8. These results suggest that the risk of lodging can be estimated in an areal manner prior to pinching, even though the actual occurrence is affected by wind.
We summarize the development and evaluation of new type of phospholipid polymers as a solubilizer for poorly water-soluble compounds. That is, a water-soluble and amphiphilic ...poly(2-methacryloyloxyethyl phosphorylcholine-random-n-butyl methacrylate) contains 30 mol% hydrophilic 2-methacryloyloxyethyl phosphorylcholine units and its weight-averaged molecular weight is around 5.0 × 10
4
. When the polymer is dissolved in an aqueous medium, a large portion of hydrophobic n-butyl methacrylate units assemble, forming polymer aggregates. To avoid severe biological reactions caused by conventional solubilizers, the phospholipid polymer can be applied for the solubilization of poorly water-soluble bioactive compounds. The polarity inside these polymer aggregate is the same as that of ethanol and n-butanol. Therefore, bioactive compounds, whose solubility is poor in water but good in these alcohols, can be entrapped in the polymer aggregate. The phospholipid polymer can penetrate the cell membrane by molecular diffusion, carrying inside the cell the bioactive compound, without exhibiting significant cytotoxicity. Several animal experiments have revealed that the pharmacological performance of various bioactive compound/phospholipid polymer complexes is excellent. Furthermore, functionalization of the polymer aggregate with biomolecules, such as antibodies and oligonucleotides, can be done, leading to selective capturing of the target molecules. These examples clearly indicate that water-soluble and amphiphilic phospholipid polymer is a candidate for preparing safer formulations and more effective pharmaceutical treatment with several bioactive compounds.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Liquid–liquid phase separation (LLPS) is an important phenomenon in biology, and it is desirable to develop quantitative methods to analyze protein droplets generated by LLPS. This study quantified ...the change in protein concentration in a droplet in label-free and single-droplet conditions using Raman imaging and the Raman band of water as an intensity standard. Small changes in the protein concentration with variations in pH and salt concentration were observed, and it was shown that the concentration in the droplet decreases as the conditions become less favorable for droplet formation. The effect of exposure to 1,6-hexanediol was also examined, and this additive was found to decrease the protein concentration in the droplet. A model can be proposed in which the addition of 1,6-hexanediol reduces the protein concentration in the droplet, and the droplet disappears when the concentration falls below a certain threshold value.
Abstract We considered that properties of the microenvironment surrounding cells are important for the control of the cell functions. Cytocompatible polymer hydrogels are good candidates to study ...such microenvironment. Here, we prepared spontaneously forming hydrogels composed of two polymer systems, namely poly(2-methacryloyloxyethyl phosphorylcholine -co-n- butyl methacrylate -co-p- vinylphenylboronic acid) (PMBV) and poly(vinyl alcohol) (PVA). The PMBV/PVA hydrogels could be reversibly dissociated by the addition of d -sorbitol. The storage modulus was measured for evaluating the mechanical properties of the PMBV/PVA hydrogels. The storage modulus could be controlled in the range 0.30–2.5 kPa by changing the cross-linking density of the hydrogels. After pluripotent stem cells were encapsulated within the PMBV/PVA hydrogels during the preparation of the hydrogel under normal cell-culturing conditions, the proliferation rate and the cell cycle of the encapsulated cells were observed. Cells lived for more than three days in every PMBV/PVA hydrogel. However, the proliferation significantly depended on the storage modulus of the hydrogels. Although the cell cycle of the initial cells was heterogenous, it developed uniformity toward the G1 phase when the cells were encapsulated within the PMBV/PVA hydrogel with a storage modulus of 1.1 kPa for three days. That is, the mechanical properties of the PMBV/PVA environment influenced the biological functions of the cells encapsulated in the hydrogels. From these results, we conclude that PMBV/PVA hydrogels are useful for adjusting cell cycles and proliferation, thus providing uniform cells for applications in the field of cell engineering.
The biomimetic synthetic phospholipid polymer containing a phosphorylcholine group, 2-methacryloyloxyethyl phosphorylcholine (MPC), has improved the surface property of biomaterials. Both hydrophilic ...and anti-biofouling surfaces were prepared on polydimethylsiloxane (PDMS) with MPC grafted by surface-initiated photo-induced radical polymerization. Benzophenone was used as the photoinitiator. The quantity of the adsorbed initiator on PDMS was determined by UV absorption and ellipsometry. The poly(MPC)-grafted PDMS surfaces were characterized by XPS, ATR-FTIR and static water contact angle (SCA) measurements. The SCA on PDMS decreased from 115° to 25° after the poly(MPC) grafting. The in vitro single protein adsorption on the poly(MPC)-grafted PDMS decreased 50–75% compared to the unmodified PDMS. The surface friction of the poly(MPC)-grafted PDMS was lower than the unmodified PDMS under wet conditions. The oxygen permeability of the poly(MPC)-grafted PDMS was as high as the unmodified PDMS. The tensile property of PDMS was maintained at about 90% of the ultimate stress and strain after the poly(MPC) grafting. The surface-modified PDMS is expected to be a novel medical elastomer which possesses an excellent surface hydrophilicity, anti-biofouling property, oxygen permeability and tensile property.
Abstract Development of living cell-based devices holds great promise in many biomedical and industrial applications. To increase our understanding of the process, we investigated the biological and ...electrochemical properties of a redox phospholipid polymer hydrogel containing an electron-generating bacteria ( Shewanella oneidensis MR-1). A water-soluble and amphiphilic phospholipid polymer, poly(2-methacryloyloxyethyl phosphorylcholine- co - n -butyl methacrylate- co - p -vinylphenylboronic acid- co -vinylferrocene) (PMBVF), was our choice for incorporation into a hydrogel matrix that promotes encapsulation of bacteria and acts as an electron transfer mediator. This hydrogel formed spontaneously and encapsulated Shewanella in three-dimensional structures. Visual analysis showed that the encapsulated Shewanella maintained viability and metabolic activity even after long-term storage. Cyclic voltammetry measurement indicated that the PMBVF/poly(vinyl alcohol) (PMBVF/PVA) hydrogel had stable and high electron transfer efficiency. Amperometric measurement showed that the hydrogel could maintain the electron transfer efficiency even when Shewanella was encapsulated. Thus, the PMBVF/PVA hydrogel not only provides a mild environment for long-term bacterial survival but also maintains electron transfer efficiency from the bacteria to the electrode. We conclude that hydrogel/bacteria hybrid biomaterials, such as PMBVF/PVA/ Shewanella , may find application in the fabrication of living cell-based devices.
Abstract We fabricated multi-layered hydrogels on titanium alloy (Ti) surfaces by applying alternating layers of a water-soluble phospholipid polymer (PMBV) and polyvinyl alcohol (PVA). This was ...accomplished by a layer-by-layer (LbL) process that is based on the formation of reversible covalent bonds between the boronic acid subunits in the PMBV and the hydroxyl groups in the PVA. When placed in an aqueous medium, PMBV acquires a polymeric aggregate structure with hydrophobic domains that can effectively solubilize hydrophobic molecules such as the anticancer drug paclitaxel (PTX) used in this study. The PTX-containing PMBV layer acted as a reservoir in the multi-layered hydrogels. To obtain diverse release profiles, the PTX was loaded in either the top layer (top-type) or the bottom layer (bottom-type) of the hydrogels; additional layers of PMBV and PVA, without PTX, functioned as a diffusion-barrier. In cell culture experiments, top-type hydrogels demonstrated excessive suppression of human epidermal carcinoma A431 cell proliferation over 5 days due to the initial high concentration of released PTX. However, bottom-type hydrogels were able to maintain a constant cell number profile. The release of PTX from multi-layered hydrogels was governed by both diffusion through the diffusion-barrier and dissociation of the hydrogel through an exchange reaction of phenylboronic acid subunits with the low-molecular weight d -glucose in the cell culture medium. In the cell culture experiments, the cell cycle was arrested in S and G2/M phases, as expected following PTX-mediated growth inhibition; control hydrogels did not demonstrate any appreciable cell cycle arrest. We concluded that cell proliferation could be controlled by the concentration of PTX released from the multi-layered hydrogels prepared through the LbL process. This system when used to solubilize bioactive agents at an appropriate layer within the hydrogel has potential for localized and surface-mediated delivery of bioactive molecules from biomedical devices.
