Grafting Point Research Articles

Polymer Nanocomposites: Role of modified filler content and interfacial interaction on crystallization

The crystallization behavior of polymer nanocomposites is of great significance in scientific level and applications. In this work, the effects of modified filler contents and interfacial interactions on nucleation and crystallization were revealed by Monte Carlo simulation. The results show that the increase of filler content promotes the transformation of nucleation mode and significantly affects the crystallization rate of polymer nanocomposite system. When the modified filler contents in the system are too high, the chain mobility is greatly reduced due to the small spacing of fillers and the strong restriction of grafting points, which limits the diffusion and arrangement of segments to the nucleus and reduces the crystallization rate. By adjusting the interfacial strength between the matrix and modified fillers, it can be found that the nucleation rate of the system is determined by the changes of free energy barrier and diffusion activation energy under different interfacial interactions. In addition, for the polymer nanocomposite system with less fillers or strong interfacial interactions, it is more likely to form edge-on crystals. These results contribute to the design and preparation of high performance polymer nanocomposites.

Cystosonographic and Cystographic Evaluations of Urinary Bladder Defects Managed with Composite Colo-Peritoneal Grafts in Dogs

Radiographic and ultrasonographic evaluations of the urinary bladder architecture following autologous composite colo-peritoneal pedicle graft, as alternative tissue for urinary bladder reconstruction, in the surgical repair of experimental urinary bladder defects were carried out in two dogs. Predetermined 2 ´ 4 cm dimension of urinary bladder defect was created on the dorsum of the urinary bladder, and was patched with harvested 3 ´ 5 cm composite colo-peritoneal pedicle flap. All operations were aseptically and humanely conducted. The gross anatomical evaluation of the urinary bladder architecture was performed by ultrasonography and contrast radiography of the repaired urinary bladder. Post-surgical cystosonographic assessments on day 8 showed thickened urinary bladder wall at the point of the graft, which decreased markedly on day 21. Cystographic evaluation revealed gradual transition of the urinary bladder architecture at the point of graft with clear delineation and minimal blurring at week 2 post-operation, which gradually disappeared at weeks 10 and 14. The cystosonographic and cystographic evaluations demonstrated evidence of advanced healing and well-preserved urinary bladder architecture with no evidence of leaks. The imaging modalities are adequately diagnostic to assess urinary bladder repairs following its management with composite colo-peritoneal graft in dogs.

Discovery of unusual morphological evolution of A-graft-(B-block-C) graft terpolymers by tuning the length of B component

The self-assembly behaviors and morphological evolutions of the A-g-BC graft terpolymers in A-backbone-attractive solvents were examined by using the real-space implemented self-consistent field theory. The concentric structure-in-structure (B-enwrap-C) and surface-patched structure-on-structure (B-patch-C) multicompartment micelles were observed by tailoring the B block lengths. At longer length of B blocks, the A-g-BC graft terpolymers prefer to form the common concentric B-enwrap-C multicompartment micelles, while the B-patch-C multicompartment micelles with B patches on C surface favor the shorter length of B blocks. It was found that the formation of B-patch-C is driven by the conformational entropy of the B blocks. In addition, when the length of B block decreases into a much lower value, an unusual morphological evolution from raspberry-like to concentric multicompartment micelles was discovered, which was revealed to be driven by the conformational entropy of the inner blocks of A backbone between two adjacent graft points. The gained results could provide a deep insight into the mechanism behind the morphological evolution between concentric structure-in-structure (B-enwrap-C) and surface-patched structure-on-structure (B-patch-C) multicompartment micelles.

First report of Didymosphaeria rubi-ulmifolii associated with canker and dieback of apple trees in southern Ethiopia

Cultivation of apple trees in the highlands of Ethiopia began in 1955. In 2014, blistering of the bark due to cankers on the main stems mostly below the grafting points, followed by dieback and eventually death of apple trees, was observed in apple orchards in the Hadiya Zone in Ethiopia. This study aimed to identify the causal agent of canker and dieback symptoms on the apple trees. Symptomatic trunks from 20 trees (ten per cultivar) were sampled. Isolations were performed from ten trunks (five per cultivar). Fungus colonies with similar cultural features were obtained from all the samples, and the morphology of a representative isolate was characterized. Phylogenetic analyses of the concatenated internal transcribed spacers 1 and 2 and 5.8S rRNA gene, large subunit and actin gene regions confirmed the identity of two isolates as Didymosphaeria rubi-ulmifolii. Pathogenicity was confirmed for one isolate by inoculations of healthy branches of ‘Anna’ and ‘Dorsett Golden’ apple trees resulting in lesion formation, and subsequent re-isolation of the inoculated fungus. This study is the first report of D. rubi-ulmifolii associated with dieback of apple trees. This pathogen caused death of more than 26% of apple trees in one commercial orchard, and could cause severe losses for smallholder apple growers in Ethiopia. Future studies are required to assess the magnitude, distribution and management options of this economically important canker disease in Ethiopia.

Benchmarking Electrolyte‐Gated Monolayer MoS2 Field‐Effect Transistors in Aqueous Environments

Most electrical sensor and biosensor elements require reliable transducing elements to convert small potential changes into easy to read out current signals. Offering inherent signal magnification and being operable in many relevant environments field‐effect transistors (FETs) are the element of choice in many cases. In particular, using electrolyte gating, numerous sensors and biosensors have been realized in aqueous environments. Over the past years, electrolyte‐gated FETs have been fabricated using a variety of semiconducting materials, including graphene, ZnO, as well as conjugated molecules and polymers. Above all, using conducting polymers top‐performing devices have been achieved. Herein, an approach to use a transition metal dichalcogenide (TMDC)‐based monolayer device as a transducing element is presented. Using MoS2 monolayers, it is shown that such electrolyte‐gated devices may be regarded as very promising transducing elements for sensor and biosensor applications, enabled by their high sensitivity for environmental changes and the possibility of using the naturally occurring sulfur vacancies as grafting points of biorecognition layers. Furthermore, the behavior of such a device under prolonged operation in a dilute biologically relevant electrolyte such as phosphate buffered saline solution (PBS) is reported.

Improvement of tree growth technology in weakly growing grafting points of apple tree (Malus mill)

This article studies the technology of growing seedlings of different varieties of apples at vegetatively propagated low-growing M-IX and medium-sized MM109 grafting points and provides scientifically based data. Grafting the upper-grafted bud by removing the wooden part resulted in a significant increase in its grip. When apple varieties were grafted to M-IX grafting point without removal of the wood part, the total amount of preserved upper-grafted buds ranged from 76% to 80% by variety, while in the experimental variant of grafting without wood, this figure ranged from 85% to 95% and observed to vary in this interval. When the bud graft is made to the root collar of the grafting point, this figure does not exceed 61.7-68.6% by variety. When the bud was grafted 10 cm above the root collar, it was found to be in the range of 67.5 to 75.9%, respectively.

Impact of green initial cuttings of vegetative-active grafting points of cherry on rooting and its period, rods, and growth controlling plant substance concentration

This scientific paper presents the results of experiments on the propagation of vegetatively propagated clone grafts of cherries from green cuttings. In the experiment, the effect of the concentration of indolymic acid (IMK), the time of preparation of green cuttings and the part of the stem from which the green cuttings were obtained, on the growth of vegetatively propagated stems of cherries from green cuttings was studied. The object of study was the weakly growing vegetatively propagated VSL-2 (Krimsky-5) and CAB-6P grafts of cherries. The cuttings were treated with water concentrations of 20, 40, 60, 80, 100 mg/l to determine the optimal concentration of the growth regulating agent - IMK. Rapid acceleration of rhizogenesis processes and high root yield (78-81%) in green cuttings of cherry clone grafts were noted in the variant treated with IMK 80 mg/l water concentration. The rapid and early regeneration processes in green cuttings using the optimal concentration of IMK ensured that their conditional body diameter reached a standard (6-7 mm) size by the time of cutting grafts. In this experimental variant, the amount of plants that can be grafted has reached about 89% of the total number of plants that have taken root.

Vegetative propagation of cornelian cherry (Cornus mas L.) selections

Cornelian cherry (Cornus mas L) is one of the most valuable fruit shrubs of the Cornaceae family, and therefore the vegetative propagation of the valuable selections is necessary because the material obtained must be used for the future. 4 genotypes were studied (2 perspective selections: H1 and H3 and two cultivars used as a control: ‘De Bucovăț’ (B) and ‘De Orhei’ (O) and propagated by grafting (the grafting method used was improved copulation. Biometric observations were focused on diameter below the point of graft (mm), diameter at the graft point (mm), diameter above the graft point (mm), height of graft (cm), number of anticipated, average length of the anticipated (cm), the sum of the anticipated length (cm), the growth increase (cm). Based on the results obtained, it can be concluded that the grafting method, enhanced copulation, within vegetative propagation, can be successfully used in the production of cornelian cherry planting material next to the other known methods; the growth of the anticipated shoots on plant could cause the appearance of flowering buds and implicitly earliness in fruit-setting.

INDOLEBUTYRIC ACID AND ZINC IN THE ROOTING OF ROOTSTOCK SEEDLINGS OF ‘CRAVO’ LEMON IN HYDROPONIC SYSTEM

It was intended to evaluate the influence of indolebutyric acid (IBA) and zinc upon the rooting and development of rootstock of ‘Cravo’ lemon tree transplants of bare root to the modified hydroponic system in the grafting stage. Plants of rootstocks were treated by immersion of their root system into the different solutions tested for 24 hours. The experiment was arranged in a completely randomized design with seven treatments composed of IBA doses of 50, 100 and 200 mg.L-1 and Enervig® which contains in its formulation 33.92 g.L-1 of Zn at 60, 90 and 120 ml.L-1, and distilled water as a control with three replications and nine plants per plot, amounting to 189 plants , 15 cm tall. The rootstocks were transplanted to the tubes and taken to the modified hydroponic system, being evaluated (1) the development of the plants and (2) the time needed for the rootstocks to reach the grafting stage, considered ideal between 5 and 6 mm in diameter. The treatment with a solution of 100 mg.L-1of IBA proved superior to the others in the development of height and biomass yield and tended to provide greater stem diameter development. The grafting point was obtained, on average at 70 days after transplanting and the production of Rangpur lime trees in a hydroponic system may be recommended. When the root system of the ‘Cravo’ lemon tree was treated with 100 mg.L-1 solution the IBA grafting point was obtained at 45 days after transplanting.

Synthesis of hyaluronated poly(exo-7-oxabicyclo[2.2.1]hept-5-en-2,3-dicarboxylic anhydride) brushes via a combination of surface-initiated ring-opening metathesis polymerization and thiol-ene click reaction

Well-defined hyaluronated poly(exo-7-oxabicyclo[2.2.1]hept-5-en-2,3-dicarboxylic anhydride) [poly(EHDA)-HA] brushes on the hydroxyl-terminated silicon (Si–OH) surface were prepared through the combination of surface-initiated ring-opening metathesis polymerization (ROMP) and thiol-ene click reaction. This process was realized in four successive steps: (i) formation of self-assembled monolayer of (3-aminopropyl) triethoxysilane on the Si–OH surface (Si-APTES), (ii) bonding of EHDA monomer to the Si-APTES surface, (iii) synthesis of poly(EHDA) brushes via surface-initiated ROMP and (iv) coupling of thiolated hyaluronic acid (Th-HA) to poly(EHDA) chains via thiol-ene click reaction. Surface wettability, surface morphology and chemical compositions of poly(EHDA)-HA brushes were characterized by contact angle measurements, atomic force, microscopy and X-ray photoelectron spectroscopy, respectively. Grafting density (σ, chains nm−2) and average distance between grafting points (D, nm) of the poly(EHDA) brushes were measured to be 0.50 chains nm−2 and 1.65 nm, independent of the [catalyst]/[monomer] ratios, which indicated that high grafting was created on the silicon substrate. However, low amounts of HA molecules were bonded to poly(EHDA) chains due to the high volume of Th-HA chains creating some steric hindrances. Biocompatible property of the poly(EHDA)-HA brushes are useful candidate for making advanced biological devices to control the behavior of biomolecules on surfaces.

Physiological changes and growth of soursop plants under irrigation with saline water and H2O2 in post-grafting phase

The low availability of water associated with high salt concentrations in irrigation water has become one of the leading challenges for agricultural production in the semiarid region of Northeastern Brazil. Thus, the study of strategies to enable the use of saline water in agriculture is essential. From this perspective, this study aimed to evaluate alterations in gas exchange, chloroplast pigments, and cell damage in soursop (Anonna muricata L.) irrigated with saline water and under exogenous application of hydrogen peroxide (H2O2) in the post-grafting phase. A study was conducted in Campina Grande, PB, under greenhouse conditions. The treatments were distributed in a randomized block design, in a 4 × 2 factorial arrangement, consisting of four levels of electrical conductivity of water (ECw; 1.6; 2.4; 3.2 and 4.0 dS m-1) and two concentrations of H2O2 (0 and 20 µM) with four replications. Irrigation water salinity from 1.6 dS m-1 caused changes in the stomatal conductance, respiration, and internal CO2 concentration of soursop plants. A 20 µM concentration of H2O2 reduced the effects of salinity on transpiration and CO2 assimilation values, in addition to promoting the biosynthesis of photosynthetic pigments and reducing cell damage in soursop plants, at 150 days after transplantation. The exogenous application of 20 µM H2O2 reduced the deleterious effects of salinity on the stem diameter of both rootstock and scion in soursop plants irrigated with ECw of 1.6 dS m-1. The exogenous application of 20 µM H2O2 was not efficient in mitigating the damage caused by salinity on the stem diameter of the soursop at grafting point.

Damage to lemon tree caused by simulated drift of herbicides

The use of herbicides, in particular clomazone and glyphosate, applied in isolation or in a tank mix, is very common in rice, soybeans, corn and sugarcane fields and the drift of these herbicides can cause damage in sensitive species grown nearby. The purpose of this work was to evaluate the effects of the simulated drift of clomazone and glyphosate applied in an isolated way or mixed in a spray on lemon tree plants. The experiment was installed in a greenhouse in pots with a capacity of 15 L containing sieved soil and an experimental design of randomized blocks was adopted, arranged in a 3 x 5 factorial scheme, with four replications. Plants with two years of development were used. The treatments tested were, clomazone, glyphosate and both mixed, and the decreasing doses of the recommended commercial product: 100, 75, 50, 25 and 0% to simulate herbicide drift. Was evaluated variables, phytotoxicity at 14, 28, 46 and 100 days after application of treatments; plant height, crown volume, the trunk diameter of the rootstock, trunk diameter of the graft and trunk diameter at the grafting point at 0 and 100 days after application of treatments; and liquid assimilation of CO2 at 10 and 60 days after application of treatments. Among the tested herbicides, the one that presented the highest phytotoxicity and the lowest liquid assimilation of CO2 in lemon tree plants was the glyphosate + clomazone mixture. Increases in trunk diameter of the rootstock, grafting point, graft and crown volume did not show significant effects with simulated drift. The plant height presented a greater reduction with the increase of the herbicide doses, mainly glyphosate. That there are considerable losses in lemon tree plants when herbicide drift occurs, mainly by glyphosate and its mixture with clomazone.

Armut Fidanlarının Morfolojik Özellikleri Üzerine Anaçların ve Çeşitlerin Etkisi

Meyve yetiştiriciliğinde anaçlar üzerine aşılanan çeşidin büyüme ve gelişmesini etkilediği gibi çeşitler de üzerlerine aşılandıkları anacı etkilemektedirler. Günümüzde armut yetiştiriciliği farklı büyüme özelliklerine sahip anaçlar üzerine aşılanarak çoğaltılan fidanlar ile yapılmaktadır. Bitkilerin kök sistemini oluşturacak olan anaçların seçimi çeşit seçimi kadar önemlidir. Bu çalışma, aşılı armut fidanlarının morfolojik özellikleri üzerine bazı armut klon anaç ve çeşitlerinin etkisini belirlemek amacıyla 2018-2019 yılları arasında yürütülmüştür. Bu çalışmada, ‘Deveci’, ‘Williams’, ‘Santa Maria’ ve ‘Abate Fetel’ armut çeşitleri Fox9, Fox11, OHxF87 ve OHxF333 armut klon anaçları üzerine dilciksiz aşı yöntemiyle aşılanmıştır. Araştırmada fidanlarda anaç çapı (mm), aşı noktası çapı (mm), aşı sürgününde yan dal sayısı (adet), boğum sayısı (adet), boğum arası mesafe (cm), yaprak eni ve boyu (cm), yaprak sapı uzunluğu (cm) ve kalınlığı (mm), sürgündeki yaprak sayısı (adet), ortalama ve toplam yaprak alanı (cm2) incelenmiştir. Araştırmada tüm parametreler üzerine anaçların ve çeşitlerin değişen düzeylerde etkiye sahip olduğu saptanmıştır. En yüksek aşı noktası çapı anaçlar bakımından Fox9; çeşitler bakımından ‘Deveci’de belirlenmiştir. Araştırmada en fazla yan dal sayısı ve yaprak sayısı Fox9 üzerine aşılı ‘Deveci’ çeşidinde tespit edilmiştir. Ortalama yaprak alanı en fazla ‘Santa Maria’, bitki başına toplam yaprak alanı ise ‘Deveci’ çeşidinde belirlenmiştir. Sürgündeki boğum sayısının Fox9 anacında diğer anaçlardan daha yüksek olduğu belirlenmiştir. Boğum arası mesafenin Fox9 anacında diğer anaçlardan daha düşük olduğu saptanmıştır. ‘Santa Maria’ çeşidinde boğum arası mesafenin diğer çeşitlerden daha yüksek olduğu tespit edilmiştir. Bu araştırmanın sonucunda morfolojik özellikler bakımından Fox9 anacı üzerine aşılı ‘Deveci’ çeşidinin diğer çeşit/anaç kombinasyonlarından daha iyi değerlere sahip olduğunu söyleyebiliriz.

Molecular Description of Grafted Supramolecular Assemblies on Gold Surfaces: Effect of Grafting Points and Chain Lengths.

The association of 4 aminoazobenzene (4AA) with two different water-soluble hosts, β-cyclodextrins (β-CD) and calixarenesulfonates (CnS), was studied in heterogeneous conditions using molecular simulations. This situation is achieved by immobilization of macrocycles onto a gold Au(111) surface. Several factors that can influence the binding properties are investigated here through the chain length of alkylthiols spacer of the surface-immobilized host and the number of attachment points to the surface. A conformational change of β-CD as a function of the chain length is evidenced upon grafting on the gold surface, whereas CnS does not show any changes. It is then possible to tune the thermodynamic properties of β-CD by changing the grafted chain length and forming a larger hydrophobic region. The mechanisms of insertion of guests into the cavities are similar to those obtained in a homogeneous system. 4AA is included longitudinally in the β-CD cavity, and it interacts rather with the sulfonate groups of the CnS located at the outer edge of the cavity.

Endocannabinoids release after Osteopathic Manipulative Treatment. A brief review.

Since 70's, scientific research has analyzed how many acute and chronic issues can affect body systems. In case of depression, chronic pain and overtraining, centrals and peripherals systems act to manage and maintain body adaptations. The aim of this study is to evaluate if the osteopathic treatment can increase the release of Cannabinoid receptor (CB) and promote the linkage with their receptors. Documents research is based on PubMed and Google Scholar databases. Keywords used were "osteopathic treatment", "manual therapy", "endocannabinoid", "beta endorphin (BE)", and " CB1" "massage". From 70 articles collected (published in the last 10 years) 52 were excluded as non-relevant to the study aim. The Key points have been the similar results found by different authors during different treatment periods and with different doses. From 22 articles examined, 13 have established positive effects on CB increasing post osteopathic treatment, three articles have indicated the most targeted tissues in which the substances are most expressed, two articles indicate how physical activities produce antalgic effects by increasing CB's values. As a result of this review, osteopathic manipulation treatment seems to be a valid and effective instrument for the treatment of a series of pathologies such as chronic low back pain, fibromyalgia, spinal cord lesions, myofascial graft point, migraine, GI tract dysfunctions, and depression.

Combination of liver graft sonographic grading and point shear wave elastography to reduce early allograft dysfunction after liver transplantation.

To analyze the performance of a liver graft sonographic grading system and point shear wave elastography (PSWE) in predicting early allograft dysfunction (EAD) after liver transplantation (LT). Successive brain-dead donors and liver recipients in our hospital from March 2017 to May 2018 were retrospectively recruited. All donors underwent PSWE examination, abdominal ultrasonography, and sonographic grading (grade 0 to grade 5). Donors with ≥ 10 valid PSWE examinations and a failure rate of < 60% were included. For all recipients, abdominal ultrasonography and blood tests for biologic parameters were performed preoperatively and daily postoperatively to screen for EAD. The recipients and their grafts were classified into EAD and non-EAD groups. Statistical analyses were performed to analyze the correlations among liver stiffness (LS), liver graft sonographic grading, and EAD. Thirty-two donors and 32 corresponding liver recipients were enrolled (15 cases in the EAD group; 17 in the non-EAD group). There were no grade 0, 1, or 2 cases in the two groups. For prediction of EAD in recipients after LT, the AUC for PSWE was 0.929 and the AUC for combination of PSWE and sonographic grading system was 0.935. Combination of PSWE and sonographic grading system can predict postoperative EAD in LT recipients with high sensitivity. Abnormal results may suggest a need for liver biopsy preoperatively, thus avoiding unnecessary surgical preparation for liver procurement. • Combination of PSWE with new sonographic grading system is useful for preoperative evaluation of liver grafts from brain-dead donors. • EAD is as a criterion for evaluating the diagnostic value of PSWE and sonographic grading system. • Combination of PSWE and sonographic grading system can predict postoperative EAD in LT recipients with high sensitivity.

Different environments and doses of controlled-release fertilizer in peach rootstocks production

The objective of this study was to evaluate the effects of different environments and doses of controlled-release fertilizer (CRF) on the initial growth of peach rootstocks [Prunus persica L. (Batsch)] cv. Capdeboscq. The experimental design was completely randomized, in a 2 x 4 factorial design, four replications and five plants per plot. The treatments were the combination of two cultivation environments (on open-air benches and greenhouse benches) and four doses of CRF (0, 2, 4 and 8 g L-1 of substrate), in the 19-06-10 NPK formulation. Ninety days after their transplanting, the variables plant height, stem diameter, number of leaves per plant, shoot dry matter, root dry matter, total dry matter, plant height and stem diameter ratio were evaluated in addition to the Dickson Quality Index. All morphological variables evaluated presented a quadratic positive response to the increase of the applied fertilizer until the dosage of maximum technical efficiency (around 6,2 g L-1). The maintenance of the plants in greenhouse benches and the incorporation of 4 g L-1 CRF to the substrate ensures greater efficiency in the input use, reducing the amount of time necessary for peach trees cv. Capdeboscq to achieve their grafting point and to be used as rootstocks.

Grafting density of oligo-bottle-brushes on silicon surface: effect of mole fraction of RAFT agent-functionalized alkenes in mixed self-assembled monolayers

The purpose of the study is to prepare of novel oligo-(N-(2-hydroxypropyl) methacrylamide)-g-poly(lactic acid) bottle-brushes with different grafting density on the silicon surface. Firstly, the mixtures of 9-decen-1-ol (DO, functional interconnection molecule) and 1-undecene (UD) molecules were attached to the hydrogen-terminated silicon surface by UV irradiation under molecular self-assembly conditions. Secondary, 4-cyano-4-(propylsulfanylthiocarbonyl) sulfanylpentanoic acid RAFT agent was immobilized onto DO molecules by ester reaction, followed by the interface-mediated RAFT polymerization of pre-synthesized N-[(2-hydroxypropyl) methacrylamide]-g-poly(lactic acid) macromonomer. The systematic control of the RAFT agent-functionalized alkene concentration afforded by the mixed self-assembled monolayers on the silicon surface enabled the grafting density and the average distance between grafting points of the polymer chains to independently control. The phase image taken with atomic force microscopy has shown that the silicon surfaces were coated with the bottle-brushes.

Synthesis of temperature and light sensitive mixed polymer brushes via combination of surface-initiated PET–ATRP and interface-mediated RAFT polymerization for cell sheet application

In this study, a series of temperature and light sensitive mixed polymer brushes consisting of poly(2-(2-methoxyethoxy) ethyl methacrylate) [poly(MEO2MA)] and poly(N-[4-[(4-nitrophenyl) azo] phenyl] acrylamide) [poly(NPAPAA)] units were grown on silicon wafer via the combination of surface-initiated photoinduced electron transfer-atom transfer radical polymerization (PET-ATRP) and interface-mediated reversible addition-fragmentation chain transfer (RAFT) polymerization. This process was realized in five consecutive steps: (i) coupling of previously synthesized (3-aminopropyl) triethoxysilane-2-bromoisobutyryl bromide (APTES-BIBB) and (3-aminopropyl) triethoxysilane-t-butoxycarbonyl (APTES-t-BOC) mixtures to the Si-OH surface under self-assembly monolayer conditions (ii) synthesis of poly(MEO2MA) units via surface-initiated PET-ATRP (iii) replacement of terminal-Br atoms at poly(MEO2MA) units with biocompatible maleimide molecules (iv) removal of the t-BOC group from APTES-t-BOC and bonding of the RAFT agent to the APTES, and (v) synthesis of poly(NPAPAA) units via the interface-mediated RAFT polymerization. The surface compositions of APTES-BIBB and APTES-t-BOC molecules were determined by the water contact angle data analyzed with the Israelachvili-Gee model and by the X-ray photoelectron spectroscopy measurements. The grafting density (σ, chains nm−2) and the average distance between grafting points (D, nm) of the mixed polymer brushes are about 0.56 chains nm−2 and 1.52 nm, respectively, indicating high grafting density. The lower critical solution temperatures (LCSTs), trans-cis and cis-trans transition times were in the range of 24.6–29.2 °C, 10–25 min and 8–20 min, respectively, depending on the surface composition of the polymer brushes. Cell culture studies revealed successful cell detachment either via the temperature reduction or UV irradiation methods. The cell recovery ratios were recorded as 99.05 ± 0.45% and 83.95% ± 0.58%, respectively. These experimental findings provided basic information at the molecular level in the preparation of temperature and light- sensitive bioactive surfaces for cell sheet preparation and detachment state.

Dynamics of Soft and Hairy Polymer Nanoparticles in a Suspension by NMR Relaxation.

The design of surface-modified functional nanoparticles (NPs) is used to control the properties of the NPs and the NP/environment interactions. The efficient control of the final behavior of the NPs demands a comprehensive understanding of the resulting system. This is particularly challenging for systems with an architecture of the type polymer core–polymer canopy. In such systems, one of the key parameters influencing the behavior of the NPs is the local dynamics of the polymer canopy. However, because the grafting points of the canopy are experiencing their own local dynamics, predicting the final behavior of such systems is difficult. To get a deeper understanding of NPs made of a soft and swollen polymer core and a swollen polymer canopy, we prepared a library of hairy NPs made of a polystyrene (PS) core and a canopy of grafted poly(methyl acrylate) (PMA) chains. The softness of the PS core and the thickness of the PMA canopy were controlled, and the behavior and dynamics of the soft and hairy PS–PMA NPs in suspension were measured by 1H NMR relaxation and dynamic light scattering. It was observed that the rigid PS core slowed down the subsegmental dynamics of the PMA chains, while thick PMA canopies accelerated the relaxation of the PS core. The dynamics of the NPs in suspension was the result of the interplay between the PS core and the PMA canopy.