Bean-Pod-Inspired 3D-Printed Phase Change Microlattices for Solar-Thermal Energy Harvesting and Storage.

Effective and reliable encapsulation of phase change materials (PCMs) is essential and critical to the high-performance solar-thermal energy harvesting and storage. However, challenges remain pertaining to manufacturing scalability, high efficiency in energy storage/release, and anti-leakage of melted PCMs. Herein, inspired by natural legume, a facile and scalable extrusion-based core-sheath 3D printing strategy is demonstrated for directly constructing bean-pod-structured octadecane (OD)/graphene (BOG) phase change microlattices, with regular porous configuration as well as individual and effective encapsulation of OD "beans" into highly interconnected graphene network wrapping layer built by closely stacked and aligned graphene sheets. The unique architectural features enable the ready spreading of light into the interior of phase change microlattice, a high transversal thermal conductivity of 1.67 W m-1 K-1 , and rapid solar-thermal energy harvesting and transfer, thereby delivering a high solar-thermal energy storage efficiency, and a large phase change enthalpy of 190 J g-1 with 99.1% retention after 200 cycles. Most importantly, such encapsulated PCMs feature an exceptional thermal reliability and stability, with no leakage and shape variation even at 1000 thermal cycles and partial damage of BOG. This work validates the feasibility of scalably printing practical encapsulated PCMs, which may revolutionize the fabrication of composite PCMs for solar-thermal energy storage devices.

Highly aligned welding of ultrathin graphene layer to robust carbon nanotube film for significantly enhanced thermal conductivity.

Carbon nanotube (CNT) films have demonstrated great potential for highly efficient thermal management materials. However, how to enable a combined feature of excellent thermal conductivity and structural robustness, which is crucial for the high-performance realization, still remains challenging. Herein, an effective and facile strategy to solve the problem was proposed by developing a graphene (G)/CNT film with highly aligned welding of ultrathin G layer to robust CNT film. The unique architectural features of the obtained composite film enabled a high tensile strength (116 MPa) and electric conductivity (1.7 × 103S cm-1). Importantly, the thermal conductivity was significantly improved compared to neat CNT film, and reached as high as 174 W m-1K-1. In addition, the G/CNT film featured a superior electromagnetic shielding performance. This work provides useful guidelines for designing and fabricating the composite CNT film with prominent thermal conductivity, as well as excellent mechanical and electrical properties.

A versatile ratiometric nanosensing approach for sensitive and accurate detection of Hg2+ and biological thiols based on new fluorescent carbon quantum dots.

Herein, we first reported a facile synthesis method for fabrication of highly photoluminescent carbon quantum dots (CQDs) using sodium alginate as the carbon source and histidine as both the nitrogen source and functional monomer by one-pot hydrothermal synthesis. The as-prepared CQDs gave a high quantum yield of 32%. By employing the new CQDs and rhodamine B (RhB), we demonstrated a simple, facile, sensitive, and accurate ratiometric sensor for detection of Hg2+ and biological thiols. The photoluminescence of CQDs in the ratiometric sensor can be selectively and intensively suppressed by Hg2+ due to strong electrostatic interaction between the surface functional groups of the CQDs and Hg2+. When glutathione (GSH) was introduced into the "Turn Off" CQDs-RhB-Hg2+ sensing system, the fluorescence of the CQDs can be recovered rapidly due to the stronger affinity between thiol and Hg2+, while the fluorescence of the RhB remained constant in this sensing process. Based on the above principle, the ratiometric strategy for detecting Hg2+ and GSH can be achieved readily, and gives satisfactory limit of detections (LODs) of 30 and 20 nM for Hg2+ and GSH, respectively. The dual-emission fluorescent CQDs-RhB sensor does not need the complicated molecular design and the synthesis of dual-emission fluorophores. Meanwhile, the feasibility of the proposed method for analysis of water samples, food samples, and biological samples (plasma from mice oxidative stress study) was investigated. The developed ratiometric nanosensor is proven to be facile, with less sample consumption, rapid, lost cost, highly sensitive, and very selective for Hg2+ and biological thiol detection, which offers a new approach for environmental, food, and biological analysis. Graphical abstract Ratiometric nanosensing approach detection of Hg2+ and biological thiols.

Facile and Sensitive Fluorescence Sensing of Alkaline Phosphatase Activity with Photoluminescent Carbon Dots Based on Inner Filter Effect.

A simple and sensitive fluorescent assay for detecting alkaline phosphatase (ALP) based on the inner filter effect (IFE) has been proven, which is conceptually different from the previously reported ALP fluorescent assays. In this sensing platform, N-doped carbon dots (CDs) with a high quantum yield of 49% were prepared by one-pot synthesis and were directly used as a fluorophore in IFE. p-Nitrophenylphosphate (PNPP) was employed to act as an ALP substrate, and its enzyme catalytic product (p-nitrophenol (PNP)) was capable of functioning as a powerful absorber in IFE to influence the excitation of fluorophore (CDs). When in the presence of ALP, PNPP was transformed into PNP and induced the absorption band transition from 310 to 405 nm, which resulted in the complementary overlap between the absorption of PNP and the excitation of CDs. Because of the competitive absorption, the excitation of CDs was significantly weakened, resulting in the quenching of CDs. The present IFE-based sensing strategy showed a good linear relationship from 0.01 to 25 U/L (R(2) = 0.996) and provided an exciting detection limit of 0.001 U/L (signal-to-noise ratio of 3). The proposed sensing approach was successfully applied to ALP sensing in serum samples, ALP inhibitor investigation and phosphatase cell imaging. The presented IFE-based CDs fluorescence sensing strategy gives new insight on the development of the facile and sensitive optical probe for enzyme activity assay because the surface modification or the linking between the receptor and the fluorophore is no longer required.

Ultrasound Detection of Myocardial Ischemic Memory Using an E-Selectin Targeting Peptide Amenable to Human Application.

Vascular endothelial leukocyte adhesion molecules, such as E-selectin, are acutely upregulated in myocardial ischemia/reperfusion and are thus "ischemic memory" biomarkers for recent cardiac ischemia. We sought to develop an ultrasound molecular imaging agent composed of microbubbles (MBs) targeted to E-selectin to enable the differential diagnosis of myocardial ischemia in patients presenting with chest pain of unclear etiology. Biodegradable polymer MBs were prepared bearing a peptide with specific human E-selectin affinity (MBESEL). Control MBs had scrambled peptide (MBCTL) or nonspecific IgG (MBIgG). MBESEL adhesion to activated rat endothelial cells (ECs) was confirmed in vitro in a flow system and in vivo with intravital microscopy of rat cremaster microcirculation. Ultrasound molecular imaging of recent myocardial ischemia was performed in rats 4 hours after transient (15 minutes) coronary occlusion. MBESEL adhesion was higher to inflamed versus normal ECs in vitro; there was no difference in MBCTL or MBIgG adhesion to inflamed versus normal ECs. There was greater adhesion of MBESEL to inflamed versus noninflamed microcirculation and minimal adhesion of MBCTL or MBIgG under any condition. Ultrasound imaging after injection of MBSEL demonstrated persistent contrast enhancement of the previously ischemic region. Videointensity in postischemic myocardium after MBESEL was higher than that in the nonischemic bed (11.6 ± 2.7 dB vs 3.6 ± 0.8 dB, p < .02) and higher than that after MBCTL (4.0 ± 1.0 dB, p < .03) or MBIgG (1.7 ± 0.1 dB, p < .03). MBs targeted to E-selectin via a short synthetic peptide with human E-selectin binding affinity enables echocardiographic detection of recent ischemia, setting the stage for clinical myocardial ischemic memory imaging to identify acute coronary syndromes.

Ultrasound detection of myocardial ischemic memory using an E-selectin targeting peptide amenable to human application.

Vascular endothelial leukocyte adhesion molecules, such as E-selectin, are acutely upregulated in myocardial ischemia/reperfusion and are thus "ischemic memory" biomarkers for recent cardiac ischemia. We sought to develop an ultrasound molecular imaging agent composed of microbubbles (MBs) targeted to E-selectin to enable the differential diagnosis of myocardial ischemia in patients presenting with chest pain of unclear etiology. Biodegradable polymer MBs were prepared bearing a peptide with specific human E-selectin affinity (MBESEL). Control MBs had scrambled peptide (MBCTL) or nonspecific IgG (MBIgG). MBESEL adhesion to activated rat endothelial cells (ECs) was confirmed in vitro in a flow system and in vivo with intravital microscopy of rat cremaster microcirculation. Ultrasound molecular imaging of recent myocardial ischemia was performed in rats 4 hours after transient (15 minutes) coronary occlusion. MBESEL adhesion was higher to inflamed versus normal ECs in vitro; there was no difference in MBCTL or MBIgG adhesion to inflamed versus normal ECs. There was greater adhesion of MBESEL to inflamed versus noninflamed microcirculation and minimal adhesion of MBCTL or MBIgG under any condition. Ultrasound imaging after injection of MBSEL demonstrated persistent contrast enhancement of the previously ischemic region. Videointensity in postischemic myocardium after MBESEL was higher than that in the nonischemic bed (11.6 ± 2.7 dB vs 3.6 ± 0.8 dB, p < .02) and higher than that after MBCTL (4.0 ± 1.0 dB, p < .03) or MBIgG (1.7 ± 0.1 dB, p < .03). MBs targeted to E-selectin via a short synthetic peptide with human E-selectin binding affinity enables echocardiographic detection of recent ischemia, setting the stage for clinical myocardial ischemic memory imaging to identify acute coronary syndromes.

Collagenase-labile polyurethane urea synthesis and processing into hollow fiber membranes.

As a means to stimulate wound healing, a hollow fiber membrane system might be placed within a wound bed to provide local and externally regulated controlled delivery of regenerative factors. After sufficient healing, it would be desirable to triggerably degrade these fibers as opposed to pulling them out. Accordingly, a series of enzymatically degradable thermoplastic elastomers was developed as potential hollow fiber base material. Polyurethane ureas (PUUs) were synthesized based on 1, 4-diisocyanatobutane, polycaprolactone (PCL) diol and polyethylene glycol (PEG) at different molar fractions as soft segments, and collagenase-sensitive peptide GGGLGPAGGK-NH2 as a chain extender (defined as PUU-CLxEGy-peptide, where x and y are the respective molar percents). In these polymers, PEG in the polymer backbone decreased tensile strengths and initial moduli of solvent-cast films in the wet state, while increasing water absorption. Collagenase degradation was observed at 75% relative PEG content in the soft segment. Control PUUs with putrescine or nonsense peptide chain extenders did not degrade acutely in collagenase. Conduits electrospun from PUU-CL25EG75-peptide and PUU-CL50EG50-peptide exhibited appropriate mechanical strength and sustained release of a model protein from the tube lumen for 7 days. Collapse of PUU-CL25EG75-peptide tubes occurred after collagenase degradation for 3 days. In conclusion, through molecular design, synthesis and characterization, a collagenase-labile PUU-CL25EG75-peptide polymer was identified that exhibited the desired traits of triggerable lability, processability, and the capacity to act as a membrane to facilitate controlled protein release.

Rapidly degradable konjac glucomannan hydrogels cross-linked with olsalazine for colonic drug release.

BACKGROUND: Polysaccharide hydrogel is one of the most important materials for the colon target drug release system. However, the degradation time of polysaccharide hydrogel is much longer than the retention time in the colon. The drugs are expelled from the body before being released. OBJECTIVE: In order to match the degradation of drug carriers and their retention time in the colon, a rapidly degradable konjac glucomannan (KGM) hydrogel was designed for colon target drug release. METHODS: A crosslinker containing azo bond, olsalazine, was used to prepare the rapidly degradable KGM hydrogel. The degradation and drug release of the hydrogels with different crosslinking densities in the normal buffer and the human fecal medium were studied to evaluate the efficiency of colon drug release. RESULTS: More than 50% of the KGM hydrogel by weight was degraded and more than 60% of the 5-fluorouracil (5-Fu) was released within 48 h in 5% w/v human fecal medium. CONCLUSION: The drug was released more rapidly in a simulated colon environment than in a normal buffer. Furthermore, the drug release was controlled by the degradation of the hydrogel. The KGM hydrogel containing azo crosslinker has great potential for colon drug release.

Efficacy of cognitive behavioral therapy for insomnia in the perinatal period: a meta-analysis of randomized controlled trials.

The meta-analysis aims to explore the effect of cognitive behavioral therapy for insomnia (CBT-I) in the perinatal period. Randomized controlled trials (RCTs) assessed the effects of CBT-I in perinatal women with insomnia, published in English, were eligible. Electronic searches were performed using PubMed, Embase (Elsevier), PsycINFO (Ebsco), and Web of Science (Clarivate Analytics). Insomnia Severity Index (ISI) as the primary outcome was used to estimate the pooled effects and durable efficacy of CBT-I. The secondary outcome measures were Edinburgh Postnatal Depression Scale (EPDS) and Pittsburgh Sleep Quality Index (PSQI). Of 46 studies reviewed, seven studies met the inclusion criteria. The meta-analysis indicated significant improvement in insomnia as measured with the ISI (standardized mean difference (SMD) = - 0.62, 95% confidence intervals (CI) - 0.77, - 0.47, I2 = 28%). At the follow-up time point, the meta-analysis indicated the durable efficacy of CBT-I (SMD = - 0.47, 95% CI - 0.90, - 0.03, I2 = 73%). Definite improvement of CBT-I on EPDS (SMD = -0.31, 95% CI - 0.55, - 0.06, I2 = 33%) and PSQI (SMD = - 0.82, 95% CI - 1.27, - 0.38, I2 = 68%) score change post-intervention were found. In sub-analyses, CBT-I had similar effect sizes, independent of possible modifiers (study population, comparison group, delivery format, etc.). This meta-analysis demonstrates that CBT-I is effective in alleviating insomnia, depression, and sleep quality among perinatal women. It is equally important to find that CBT-I has a durable efficacy on insomnia in the perinatal period. However, it is necessary to include larger samples and conduct rigorous RCTs to further explore this issue. Supplementary Information: The online version contains supplementary material available at 10.1007/s41105-023-00502-z.

Long-Lifespan Fibrous Aqueous Ni//Bi Battery Enabled by Bi2O3-Bi2S3 Hierarchical Heterostructures.

Bismuth oxide (Bi2O3) materials are considered as great promising anodes for aqueous batteries on account of the high capacity as well as wide potential plateau. Nevertheless, the low conductivity and severe volumetric change of Bi2O3 in the course of cycling are the main limiting factors for their application in energy-storage systems. Herein, we propose and design unique hierarchical heterostructures constructed by Bi2O3 and Bi2S3 nanosheets (NSs) manufactured immediately on the surface of carbon nanotube fibers (CNTFs). The Bi2O3-Bi2S3 (BO-BS) exhibits enhanced conductivity and increased stability in comparison with pure Bi2O3 and Bi2S3. The BO-BS NSs/CNTF electrode indicates exceptional rate capability and cycling stability, while creating a high reversible capacity of 0.68 mAh cm-2 at 4 mA cm-2, as anticipated. Additionally, the quasi-solid-state fibrous aqueous Ni//Bi battery that was built with the BO-BS NSs/CNTF anode delivers an exceptional cycling stability of 52.7% capacity retention after 4000 cycles at 80 mA cm-2, an ultrahigh capacity of 0.35 mAh cm-2 at 4 mA cm-2, and a high energy density of 340.1 mWh cm-3 at 880 mW cm-3. This work demonstrates the potential of constructing hierarchical heterostructures of bismuth-based materials for high-performance aqueous Ni//Bi batteries and other energy-storage devices.

Gene expression mediated by dendrimer/DNA complexes encapsulated in biodegradable polymer microspheres.

A convenient and effective 'ultrasonic dispersion method' was used to fabricate vector/DNA complexes encapsulated microspheres. Polyamidoamine (PAMAM) dendrimer/DNA complexes protected by a water-soluble polymer, poly-alpha,beta-[N-(2-hydroxyethyl)-L-aspartamide] (PHEA), were encapsulated in a polymer film mainly composed of cholic acid functionalized star poly(DL-lactide), which degraded through surface erosion mechanism with a fast degradation rate. The PAMAM/DNA complexes encapsulated polymer film was then immersed in ethanol and ultrasonicated to afford the microspheres. The in vitro gene transfections showed PAMAM/DNA complexes protected by PHEA exhibited a much higher transfection activity compared with PAMAM/DNA complexes without the protection by PHEA. The expressions of pGL3-Luc in HEK293 cells could be effectively mediated by the polymer film and microspheres with the presence of PHEA. The ultrasonic dispersion method, which did not involve toxic organic solvents, could keep the bioactivity of DNA and offer good control over the size of microspheres.

All Binder-Free Electrodes for High-Performance Wearable Aqueous Rechargeable Sodium-Ion Batteries.

Extensive efforts have recently been devoted to the construction of aqueous rechargeable sodium-ion batteries (ARSIBs) for large-scale energy-storage applications due to their desired properties of abundant sodium resources and inherently safer aqueous electrolytes. However, it is still a significant challenge to develop highly flexible ARSIBs ascribing to the lack of flexible electrode materials. In this work, nanocube-like KNiFe(CN)6 (KNHCF) and rugby ball-like NaTi2(PO4)3 (NTP) are grown on carbon nanotube fibers via simple and mild methods as the flexible binder-free cathode (KNHCF@CNTF) and anode (NTP@CNTF), respectively. Taking advantage of their high conductivity, fast charge transport paths, and large accessible surface area, the as-fabricated binder-free electrodes display admirable electrochemical performance. Inspired by the remarkable flexibility of the binder-free electrodes and the synergy of KNHCF@CNTF and NTP@CNTF, a high-performance quasi-solid-state fiber-shaped ARSIB (FARSIB) is successfully assembled for the first time. Significantly, the as-assembled FARSIB possesses a high capacity of 34.21 mAh cm-3 and impressive energy density of 39.32 mWh cm-3. More encouragingly, our FARSIB delivers superior mechanical flexibility with only 5.7% of initial capacity loss after bending at 90° for over 3000 cycles. Thus, this work opens up an avenue to design ultraflexible ARSIBs based on all binder-free electrodes for powering wearable and portable electronics.

Dendrimer/DNA complexes encapsulated functional biodegradable polymer for substrate-mediated gene delivery.

BACKGROUND: To overcome the extracellular barriers in gene delivery and direct gene delivery to target tissues, substrate-mediated transfection, which sustains the release of naked DNA or vector/DNA complexes, and also supports cell growth, has been developed. METHODS: In the present study, polyamidoamine (PAMAM) dendrimer/DNA complexes encapsulated functional biodegradable polymer films for substrate-mediated gene delivery were prepared. To maintain the activity of DNA during dehydration, the dendrimer/DNA complexes were encapsulated in a water soluble polymer, poly alpha,beta-[N-(2-hydroxyethyl)-(L)-aspartamide], and then deposited on or sandwiched in functional polymer films with a fast degradation rate to mediate gene transfection. The in vitro gene transfections of pGL3-Luc and pEGFP-C1 plasmids in HEK293 cells mediated by different films were studied. For comparison, the transfection mediated by the film fabricated by conventional linear poly((DL)-lactide) was also investigated. RESULTS: The expression of pGL3-Luc and pEGFP-C1 plasmids could effectively be mediated by the PAMAM/DNA complexes deposited or sandwiched polymer films, with transfection efficiencies comparable to that of solution-based transfections. The cells on the functionalized star poly((DL)-lactide) film exhibited much higher gene expression compared to the cells on the conventional linear poly((DL)-lactide) film because the fast degradation rate of star poly((DL)-lactide) facilitated the access of PAMAM/DNA complexes for the cells seeded on the film. In addition, the films did not exhibit any additional cytotoxicity to the cells during the degradation and transfection. CONCLUSIONS: The fast degrading functional polymer has great potential for localized transfection.

Fabrication and in vitro drug release study of microsphere drug delivery systems based on amphiphilic poly-alpha,beta-[N-(2-hydroxyethyl)-L-aspartamide]-g-poly(L-lactide) graft copolymers.

Biodegradable amphiphilic graft copolymers with different compositions were synthesized by grafting poly(L-lactide) (PLLA) sequences onto a water-soluble poly-alpha,beta-[N-(2-hydroxyethyl)-L-aspartamide] (PHEA) backbone. The critical micelle concentration (CMC) of the graft polymers was determined by fluorescence probe technique. Using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay, the graft polymers were proved to have low cytotoxicity. Based on the specific physicochemical property of the graft copolymers, submicron sized microsphere drug delivery systems were prepared by a very convenient "ultrasonic dispersion method", which did not involve toxic organic solvents. The drug-loaded microspheres had a regular spherical shape with a narrow size distribution. A hydrophobic drug, prednisone acetate, was encapsulated into polymeric microspheres and the in vitro drug release was studied.

Synthesis of novel cholic acid functionalized branched oligo/poly(epsilon-caprolactone)s for biomedical applications.

Novel cholic acid functionalized branched oligo/poly(epsilon-caprolactone)s were synthesized through the ring-opening polymerization of epsilon-caprolactone initiated by cholic acid with hydroxyl groups. The molecular weight of the branched polymers can be adjusted by controlling the feed ratio of the initiator cholic acid to the monomer epsilon-caprolactone. Comparing with linear homopolymer poly(epsilon-caprolactone) (PCL), these branched oligo/poly(epsilon-caprolactone)s show much faster hydrolytic degradation rates, implies that our approach provides a convenient and effective strategy to accelerate degradation of the biodegradable polymers with slow degradation rates such as PCL. The cell culture experiment indicates the incorporation of cholic acid moiety to the polymer chain can improve both cell adherence and proliferation obviously.

Acoustic radiation force for vascular cell therapy: in vitro validation.

Cell-based therapeutic approaches are attractive for the restoration of the protective endothelial layer in arteries affected by atherosclerosis or following angioplasty and stenting. We have recently demonstrated a novel technique for the delivery of mesenchymal stem cells (MSCs) that are surface-coated with cationic lipid microbubbles (MBs) and displaced by acoustic radiation force (ARF) to a site of arterial injury. The objective of this study was to characterize ultrasound parameters for effective acoustic-based delivery of cell therapy. In vitro experiments were performed in a vascular flow phantom where MB-tagged MSCs were delivered toward the phantom wall using ARF generated with an intravascular ultrasound catheter. The translation motion velocity and adhesion of the MB-cell complexes were analyzed. Experimental data indicated that MSC radial velocity and adhesion to the vessel phantom increased with the time-averaged ultrasound intensity up to 1.65 W/cm², after which no further significant adhesion was observed. Temperature increase from baseline near the catheter was 5.5 ± 0.8°C with this setting. Using higher time-averaged ultrasound intensities may not significantly benefit the adhesion of MB-cell complexes to the target vessel wall (p = NS), but could cause undesirable biologic effects such as heating to the MB-cell complexes and surrounding tissue. For the highest time-averaged ultrasound intensity of 6.60 W/cm², the temperature increase was 11.6 ± 1.3°C.

Vascular endoluminal delivery of mesenchymal stem cells using acoustic radiation force.

Restoration of functional endothelium is a requirement for preventing late stent thrombosis. We propose a novel method for targeted delivery of stem cells to a site of arterial injury using ultrasound-generated acoustic radiation force. Mesenchymal stem cells (MSCs) were surface-coated electrostatically with cationic gas-filled lipid microbubbles (mb-MSC). mb-MSC was characterized microscopically and by flow cytometry. The effect of ultrasound (5 MHz) on directing mb-MSC movement toward the vessel wall under physiologic flow conditions was tested in vitro in a vessel phantom. In vivo testing of acoustic radiation force-mediated delivery of mb-MSCs to balloon-injured aorta was performed in rabbits using intravascular ultrasound (1.7 MHz) during intra-aortic infusion of mb-MSCs. Application of ultrasound led to marginalization and adhesion of mb-MSCs to the vessel phantom wall, whereas no effect was observed on mb-MSCs in the absence of ultrasound. The effect was maximal when there were 7±1 microbubbles/cell (n=6). In rabbits (n=6), adherent MSCs were observed in the ultrasound-treated aortic segment 20 min after the injection (334±137 MSCs/cm(2)), whereas minimal adhesion was observed in control segments not exposed to ultrasound (2±1 MSCs/cm(2), p<0.05). At 24 h after mb-MSC injection and ultrasound treatment, the engrafted MSCs persisted and spread out on the luminal surface of the artery. The data demonstrate proof of principle that acoustic radiation force can target delivery of therapeutic cells to a specific endovascular treatment site. This approach may be used for endoluminal cellular paving and could provide a powerful tool for cell-based re-endothelialization of injured arterial segments.

Cholic acid functionalized star poly(DL-lactide) for promoting cell adhesion and proliferation.

Cholic acid functionalized star poly(DL-lactide) was synthesized through the ring-opening polymerization of DL-lactide initiated by cholic acid. The properties and cell behaviour of the cholic acid functionalized star poly(DL-lactide) were investigated as compared with linear poly(DL-lactide)s with different molecular weights and a star poly(DL-lactide) initiated by glycerol. In comparison to linear poly(DL-lactide)s, the cholic acid functionalized star poly(DL-lactide) had better wettability and slightly higher surface energy. The cell adhesion and proliferation on different materials were evaluated using two types of cells, 3T3 mouse fibroblasts and ECV304 human endothelial cells. Compared with the linear poly(DL-lactide)s, the cholic acid functionalized star poly(DL-lactide) showed obviously improved property for cell adhesion. The cell proliferation on the cholic acid functionalized star poly(DL-lactide) was also enhanced. The improvement in cell proliferation was not so significant as compared with the improvement in cell adhesion. This modification strategy provides an effective and simple way to promote cell attachment and growth in tissue engineering.

Dendrimer/DNA complexes encapsulated in a water soluble polymer and supported on fast degrading star poly(DL-lactide) for localized gene delivery.

Polyamidoamine (PAMAM) dendrimer/DNA complexes encapsulated in a water soluble polymer, poly-alpha,beta-[N-(2-hydroxyethyl)-l-aspartamide], were supported on a cholic acid functionalized star poly(DL-lactide) film with a fast degradation rate to mediate localized gene delivery. The in vitro gene transfections of two types of cells, HEK293 and NIH3T3, were investigated. The expressions of pGL3-Luc and pEGFP-C1 plasmids in HEK293 cells indicated that the star poly(DL-lactide) supported PHEA encapsulated PAMAM/DNA complexes could effectively mediate transfection, with transfection efficiencies which were comparable to that of solution-based transfections. Whereas the PAMAM/DNA complexes directly supported on the star poly(DL-lactide) film showed a much lower expression level for HEK293, which indicated the existence of PHEA played an important role in the efficient transfection. The solid support-based transfection for NIH3T3 cells exhibited higher expressions of pGL3-Luc compared with the solution-based transfection. Encapsulating PAMAM/DNA complexes in PHEA could further improve the gene expression in NIH3T3. During the cellular transfection, the degradation of the cholic acid functionalized star poly(DL-lactide) film could be obviously detected and the degradation did not show any unfavorable effects on the gene expression, which implied this solid support-based gene delivery device had great potential for localized transfection.