Xinwu Ba

Synthesis backbone-dual-responsive of hyperbranched poly(bis(N,N-ethyl acrylamide))s by RAFT

Hyperbranched poly(bis(N,N-ethyl acrylamide))s (HPNAMs) with many vinyls as terminal groups were synthesized successfully using reversible addition fragmentation chain transfer polymerization (RAFT). Detailed analyses, based on the molecular weight, α value, degree of branching (DB), and lower critical solution temperature (LCST) obtained from nuclear magnetic resonance (NMR), multi detector-size exclusion chromatography (MDSEC), ultravioletvisible (UV-vis) spectroscopy, and dynamic light scattering (DLS), indicate that we acquired backbone-temperature and pH responsive HPNAM. Factors, such as DB, molecular weight, and pH value, that affect the LCST were investigated. It was found that the molecular weights of the hyperbranched polymers show significant influence on the LCSTs. For the HPNAMs with low molecular weight, the LCSTs decreased as the DB increased, and the LCSTs can also be adjusted by changing the pH value of solutions. Furthermore, the result of cell cytotoxicity indicates that this new dual responsive hyperbranched polymer has low cytotoxicity and exhibits potential for biomedical applications.

A new method for synthesizing hyperbranched polymers with reductive groups using redox/RAFT/SCVP

The novel hyperbranced polymers containing reductive groups were successfully prepared and characterized using redox/reversible addition fragmentation chain transfer (RAFT)/self-condensing vinyl polymerization (SCVP) method. Several redox initiating chemicals such as Cu(III)/-CONH2, Ce(IV)/-CONH2 and Ce(IV)/-OH were chosen to increase the free radical generating rate, and the chain transfer agent (CTA) was used to reduce the molecular chain propagating rate, in order to obtain polymers with high degree of branching. Detailed analyses based on the molecular weight, α value and the degree of branching of polymers (DB) obtained from 1H-NMR spectra and multi detector size exclusion chromatography (MDSEC) suggested the acquiring of hyperbranced polyacrylamides with Cu(III)/-CONH2 and Ce(IV)/-CONH2 as initiator in the presence of the CTA. Meanwhile, the as-prepared poly(N-hydroxymethyl acrylamide) (PNHAM) with higher DB value (0.48) proved that using Ce(IV)/-OH as the initiator could increase the free radical generating rate and diminish the gap between the propagating rate and the initiation rate during the reaction procedure. In addition, the effect of oxidant concentration on the Mark-Houwink index (α) value and the DB was also studied.

A Novel Water-Soluble Fluorescence Probe with Wash-Free Cellular Imaging Capacity Based on AIE Characteristics

A potential real-time imaging water-soluble fluorescent polymer (P3) is facilely prepared via one-pot method. For P3, tetraphenylethene unit serves as the fluorescent unit, poly(acryloyl ethylene diamine) (a kind of polyelectrolyte) with specific degree of polymerization acts as water-soluble part. 1 H-NMR, gel permeation chromatography (GPC), UV-vis spectroscopy, photoluminescence (PL), and confocal laser scanning microscopy are undertaken to characterize the structure and property of P3. The results of wash-free cellular imaging show that the signal-to-noise ratio is high as the concentration of P3 is 50 μg mL-1 . In addition, the pH-responsive and Cd2+ -responsive are also investigated in this paper. The results coming from pH-responsive show that P3 solution displays significant fluorescence under near neutral. And the result from the cellular imaging shows that intracellular fluorescence intensity enhances with the augment of concentration of Cd2+ , which reveals that P3 can give a hint to resolve the dilemma of traditional fluorescent dyes used as living cellular fluorescent probe.

Synthesis and Physical Properties of Hyperbranched Polymers Containing Twisted Acenes

Novel hyperbranched co-polymers HP1–HP4 with twisted acene units and truxene groups have been synthesised through Suzuki coupling reaction and characterised. Single crystal analyses showed that the model compounds 3 and 5 had twisted structures with torsion angles of 40.73° and 28.65°, respectively. The polymers show blue light emission in organic solvents and thin films, as well as high stability, which might be utilised as potential candidates for organic electronic materials.

The Synthesis of Backbone Thermo and pH Responsive Hyperbranched Poly(Bis(N,N-Propyl Acryl Amide))s by RAFT

Hyperbranched poly(methylene-bis-acrylamide), poly(bis(N,N-propyl acryl amide)) (HPNPAM) and poly(bis(N,N-butyl acryl amide)) were synthesized by reversible addition-fragmentation chain transfer polymerization. HPNPAMs showed lower critical solution temperature (LCST) due to an appropriate ratio between hydrophilic and hydrophobic groups. The effects of reaction conditions on polymerization were investigated in detail. The structure of HPNPAM was characterized by 1H NMR, FT-IR, Muti detector-size exclusion chromatography (MDSEC) and Ultravioletvisble (UV-Vis). The α value reached 0.20 and DB was 90%, indicating HPNPAMs with compact topology structure were successfully prepared. LCSTs were tuned by Mw and the pH value of the solution. The change of molecular size was assayed by dynamic light scattering and scanning electron microscope. These results indicated that the stable uniform nanomicelles were destroyed and macromolecules aggregated together, forming large particles as temperature exceeded LCST. In addition, after the cells were incubated for 24 h, the cell viability reached 80%, which confirmed this new dual responsive HPNPAM had low cytotoxicity.

Facile construction of a hyperbranched poly(acrylamide) bearing tetraphenylethene units: a novel fluorescence probe with a highly selective and sensitive response to Zn2+

Thermo-responsive hyperbranched copoly(bis(N,N-ethyl acrylamide)/(N,N-methylene bisacrylamide)) (HPEAM-MBA) was synthesized by using reversible addition–fragmentation chain-transfer polymerization (RAFT). Interestingly, the zinc ion (Zn2+) was found to have a crucial influence on the lowest critical solution temperature (LCST) of the thermo-responsive polymer. The tetraphenylethylene (TPE) unit was then introduced onto the backbone of the as-prepared thermo-responsive polymer, which endows a Zn2+-responsive “turn-off” effect on the fluorescence properties. The TPE-bearing polymer shows a highly specific response over other metal ions and the “turn-off” response can even be tracked as the concentration of Zn2+ reduces to 2 × 10−5 M. The decrement of fluorescence intensity was linearly dependent on the concentration of Zn2+ in the range of 4–18 μmol L−1. The flexible, versatile and feasible approach, as well as the excellent detection performance, may generate a new type of Zn2+ probe without the tedious synthesis of the moiety bearing Zn2+ recognition units.

Synthesis and Characterization of Fully Conjugated Ladder Naphthalene Bisimide Copolymers

Fully conjugated ladder copolymers have attracted considerable attention due to their unique fused-ring structure and optoelectronic properties. In this study, two fully conjugated ladder naphthalene diimide (NDI) copolymers, P(NDI-CZL) and P(NDI-TTL) with imine-bridged structures are presented in high yields. Both of the two copolymers have good solubility and high thermal stability. The corresponding compounds with the same structure as the copolymers were synthesized as model system. The yields for each step of the synthesis of the model compounds are higher than 95%. These results suggest that P(NDI-CZL) and P(NDI-TTL) can be synthesized successfully with fewer structural defects. The structures and optoelectronic properties of compounds and copolymers are investigated by NMR, fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-vis), and cyclic voltammetry (CV). Both in solution and as a thin film, the two copolymers show two UV-vis absorption bands (around 300–400 nm and 400–750 nm) and a very weak fluorescence. The collective results suggest that the two fully conjugated ladder copolymers can be used as potential acceptor materials.

Investigation of a halloysite-based fluorescence probe with a highly selective and sensitive “turn-on” response upon hydrogen peroxide

Inorganic halloysite nanotubes (HNTs) were modified with an organic fluorescein derivative (PA) to prepare HNTs-based hybrid fluorescence probe (HNTs-PA). Thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), solid-state 13C NMR spectroscopy, X-ray photoelectron spectroscopy (XPS), energy dispersive spectrum (EDS) and transmission electron microscopy (TEM) confirmed that PA was successfully grafted onto the lumen of HNTs to obtain HNTs-PA with a grafting degree of 6.0%. The established B–C bond endows a selective fluorescence response toward hydrogen peroxide (H2O2) to HNTs-PA. The new hybrid probe exhibited a highly specific “turn-on” fluorescence response to H2O2 over other reactive oxygen species (ROS) and common ions owing to their chemoselective boronate-to-phenol switch. The “turn-on” response could even be tracked when the additional amount of H2O2 was limited to 1 × 10−7 mol. Moreover, human lung cancer cells (A549 cells) were successfully stained and the staining intensity enhanced as time prolongs, which can be due to the overexpressed H2O2 of cancer cells. Thus, the as-prepared organic–inorganic hybrid fluorescence probe can have a broad range of applications for identification and diagnosis.

Synthesis and characterization of curcumin-incorporated glycopolymers with enhanced water solubility and reduced cytotoxicity

Curcumin is the physiologically and pharmacologically active component of turmeric (Curcuma longa L.) with attractive fluorescent property. However, the applications in live cell imaging field are restricted mainly due to the water-insolubility and cytotoxicity. To overcome this problem, curcumin-incorporated glycopolymers are synthesized by free radical copolymerization in this study. The glycopolymers are well-characterized by infrared spectroscopy (IR), nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), UV-Vis absorption spectroscopy and photoluminescence spectroscopy. Furthermore, obtained glycopolymers are assayed by MTT assay and cell imaging for supporting the potential bio application. The MTT result indicates that the introduction of carbohydrate units can reduce the cytotoxicity of curcumin unit. The live cell imaging investigations reveal that the curcuminincorporated glycopolymers are good candidates for cell imaging and may find broad applications in biological areas such as biological diagnosis, imaging, and detection.

Synthesis, characterization and fluorescent properties of water-soluble glycopolymer bearing curcumin pendant residues.

Curcumin is a potential natural anticancer drug with low oral bioavailability because of poor water solubility. The aqueous solubility of curcumin is enhanced by means of modification with the carbohydrate units. Polymerization of the curcumin-containing monomer with carbohydrate-containing monomer gives the water-soluble glycopolymer bearing curcumin pendant residues. The obtained copolymers (P1 and P2) having desirable water solubility were well-characterized by infrared spectroscopy (IR), nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), UV–Vis absorption spectroscopy, and photoluminescence spectroscopy. The copolymer P2 with a molar ratio of 1:6 (curcumin/carbohydrate) calculated from the proton NMR results exhibits a similar anticancer activity compared to original curcumin, which may serve as a potential chemotherapeutic agent in the field of anticancer medicine. Graphical abstract The prepared glycopolymer (P2) bearing curcumin residues exhibit a similar anticancer activity to original curcumin.