A series of bis(arylidene)cycloalkanone photosensitizers modified by polyethylene glycol (PEG) have been studied for two-photon excited photodynamic therapy (2PE-PDT). As compared with their prototype compounds, these PEGylated photosensitizers show enhanced water solubilities while their photophysical and photochemical properties, including linear absorption, two-photon absorption, fluorescence, and singlet oxygen quantum yield, remain unaltered. In vitro behaviors (cellular uptake, subcellular localization, photocytotoxicity in both PDT and 2PE-PDT) of these photosensitizers reveal that an optimized lipid–water partition coefficient can be obtained by adjusting the length and position of the PEG chains. Among them, the photosensitizer modified asymmetrically by two tetraethylene glycol chains presents the best performance as a 2PE-PDT candidate. Selective blood-vessel closure and obvious therapeutic effect in inhibiting the growth of tumors are confirmed by in vivo 2PE-PDT after intravenous injection of this photosensitiezer. The survival periods of treated tumor-bearing mice are significantly prolonged. This study demonstrates the feasibility of using a simple molecule to construct a potential candidate for 2PE-PDT.

To inactivate both standard strains as well as antibiotic-resistant strains of bacteria with minimum damage to host cells, three new pyridyl cationic-modified benzylidene cyclopentanone photosensitizers (PSs), P1 (with one cationic group), P2 (with two cationic groups arranged bilaterally), and P3 (with two cationic groups arranged unilaterally) were synthesized and characterized. Their selective uptakes by bacteria over HepG2 cells and their photodynamic inactivation efficiencies against Staphylococcus aureus (ATCC 6538), Escherichia coli (ATCC 25922), and the drug-resistant Escherichia coli (CA-31) were studied using methylene blue (MB) and hematoporphyrin monomethyl ether (HMME) as references. The results showed that the uptake amounts of P1, P2, and P3 by all strains were at least 2, 20, and 18 times more than those by HepG2 cells, respectively. All PSs exhibited good antimicrobial photodynamic therapy (aPDT) effects towards all three strains at low concentrations of ≤8.0 μM, while MB was invalid towards all three strains and HMME was invalid toward Escherichia coli (CA-31) at concentrations up to 32.0 μM. In particular, the minimum inhibitory concentrations (MICs) of P3 against these strains were all ≤2.0 μM, under which about 94% HepG2 cells were still alive, indicating P3 had high aPDT selectivity for bacterial cells over mammalian cells. The relationships between structure and antimicrobial properties of these cationic PSs were discussed to reveal their high photodynamic inactivation selectivity for bacterial cells.

•A novel amphiphilic acrylamide-based copolymer with porphyrin pendants was synthesized.•The copolymer exhibits a highly selective and sensitive optical response towards Hg2+ ions in aqueous solutions.•The Hg2+-induced aggregation is accompanied with an obvious red shift in the Soret band of porphyrin.•The importance of polymer main chain on the detection selectivity has been investigated.A novel amphiphilic acrylamide-based polymer with porphyrin pendants that was prepared from radical copolymerization of 5-(p-acryloyloxyphenyl)-10,15,20-triphenylporphyrin (AOTPP) and N,N-dimethylacrylamide (DMAM) has been first reported as a highly selective and sensitive optochemical sensor for Hg2+. The responsive optical properties of the polymer were investigated by UV–vis absorption spectroscopy in aqueous solutions. Upon adding Hg2+, a new peak at 456 nm in the Soret band of porphyrin molecule was induced and gave rise to a visible color change from brown–red to green, which was attributed to the formation of unique aggregates intrigued by the coordinative interaction between Hg2+ and porphyrin groups. Moreover, there is nearly no interference observed from other metal ions (Na+, Mg2+, K+, Zn2+, Ca2+, Cr3+, Co2+, Ni2+, Pb2+, Cu2+, Al3+ and Fe3+), thus indicating the excellent sensing selectivity towards Hg2+ by the sensor. On the basis of the relationship of absorbance changes and Hg2+ concentrations, the polymeric sensor is allowed for quantitative analysis of Hg2+ ion with a low detection limit of 50 nM.

Thermosensitive poly(N-isopropylacrylamide) (PNIPAM) semi-hollow spheres consisting of low density cores, dense shells and separated cavities between cores and shells were prepared via two-step precipitation polymerization. The self-cross-linked poly(N-isopropylacrylamide-co-methacrylic acid) (PNIPAM-co-PMAA) gels with low solid density were prepared in the first precipitation polymerization and served as the templates on which dense PNIPAM shells cross-linked by N,N′-methylenebis(acrylamide) (BMA) were formed in the second precipitation polymerization. The shell thickness of the semi-hollow spheres could be controlled via adjusting the feeding core/shell mass ratios. The carboxylic groups on the core were conjugated with doxorubicin (DOX) via disulfide bonds which could be degraded by the reduction of glutathione (GSH). The release of DOX from the cores could be controlled by temperature and shell thickness with the disulfide bonds degraded by GSH. The cell viability assay indicated that the semi-hollow particles conjugated with DOX by disulfide bonds showed remarkable toxicity to Hela cells, and the toxicity was related to the shell thickness of the particles.

Triethylene glycol functionalized coumarin derivatives 1–5 were synthesized and investigated as photosensitizers for one- and two-photon excited photodynamic therapy (PDT). Their absorption, fluorescence, triplet-state quantum yields, and singlet oxygen quantum yields were found to be significantly related to the substituent at the 7-position of the coumarin ring. In vitro photocytotoxicity of these derivatives toward HepG2 cells was examined and compared with a clinical drug. In vitro generation of reactive oxygen species (ROS), cellular uptake, and intracellular distribution of these derivatives were also characterized to fully reveal their structure–property relationships. The results showed that derivative 5, with a two-photon absorption cross section value of 1556 GM, could be a powerful PDT agent for both superficial diseases and solid tumors.

A type of bifunctional responsive polymer, poly(N-(2-hydroxyl-tert-butyl) acrylamide) (PHTBAM), having both reactivity and thermosensitivity was synthesized. Such polymer can be considered as a modified poly(N-isopropylacrylamide) (PNIPAM) by introducing hydroxymethyl group at α-position, which possesses responsive behavior similar to PNIPAM, and less dependence of external condition. Moreover, thermal phase transition of this polymer is completely reversible without any hysteresis. LCST of PHTBAM occurs around 23 °C, which can be modulated by copolymerization with more hydrophilic comonomer such as N-hydroxyethylacrylamide (HEAM). The LCST of the P(HTBAM-co-HEAM) copolymer can be adjusted over a wide range by increasing HEAM content up to higher lever, due to the structural similarity between HTBAM and HEAM units without destroying the PNIPAM–type main chain and loss of the response sensibility. In addition, the hydroxyl functional groups at side chain of PHTBAM provide a capability of further chemical modification for a variety of applications in material science and biotechnology.

A couple of two-photon absorption dyes containing triphenylamine groups as the electron donor were synthesized. They were combined with commonly used photoacid generator N-(trifluoromethanesulfonyloxy)-1,8-naphthalimide (NIOTf) to build two-photon acid generation systems (2PAGs). The photochemical and photophysical properties of these dyes as well as their photosensitizing mechanism were investigated. Both of the two dyes have a greatly enhanced two-photon absorption cross-section over 1000 GM. The photoacid quantum yields of 2PAGs were measured in acetonitrile solution by one-photon process. Fluorescence quenching experiments were carried out and confirmed the electron transfer mechanism in resin films. Also, the acid-catalyzed chemical amplification processes in resin films were studied with a Ti/sapphire regenerative amplifier by attenuated total reflectance Fourier transform infrared spectroscopy, and both 2PAGs exhibited superior efficiencies via two-photon absorption in comparison with isopropylthioxanthone/NIOTf system and NIOTf itself. The two-photon lithography (TPL) was carried out on a Ti/sapphire femtosecond laser system successfully with chemically amplified positive resists based on the achieved 2PAGs and the proceeding power for TPL was as low as 0.24 mW. The results suggest that these 2PAGs can be used as high-efficiency initiator for two-photon chemically amplified positive resist.Keywords: chemically amplified positive resist; intermolecular sensitization; nonionic photoacid generator; two-photon absorption; two-photon lithography;

A series of bis(arylidene)cycloalkanone compounds based on cyclobutanone, cyclopentanone, cyclohexanone and cycloheptanone, C4–C7, respectively, with a D-π-A-π-D structure containing the same donor and acceptor but different alicyclic rings was prepared. The effects of alicyclic ring size on the photophysical, photochemical and electrochemical properties of these compounds were investigated systematically. We found that an increase of the number of carbons in the central alicyclic ring leads to changes in geometry, which has significant effects on the conjugation, and photophysical and photochemical properties. These effects include decreases in the fluorescence quantum yield, transient lifetimes, peak extinction coefficients, and the singlet oxygen quantum yield with the increase of the ring size. The one-photon absorption spectra, the two-photon absorption (2PA) spectra, and the fluorescence spectra all show a hypsochromic shift with increasing ring size. The results of this study provide guidance for the design of new cycloketone-based D-π-A-π-D 2PA compounds for photopolymerization and photodynamic therapy applications.

Thermo-responsive block copolymers poly(ethylene glycol)-block-poly(N-acryloyl-2,2-dimethyl-1,3-oxazolidine), PEG-b-PADMO, based on linear PEG were prepared via a versatile reversible addition-fragmentation chain transfer (RAFT) polymerization. PEG22 (Mw = 1000) was used as the hydrophilic component, whose dehydration was the main driving force for the phase transition of these copolymers, as demonstrated by the 1H-NMR spectra. Their lower critical solution temperatures (LCSTs) could be tuned in the range of 20°C to 35°C, by adjusting the degree of polymerization (DP) of PADMO between 14–27. Furthermore, a sharp phase transition at ca. 33°C, close to the physiological temperature with minimal hysteresis, was observed for the PEG22-b-PADMO14 copolymer. Moreover, excellent reversibility and reproducibility were displayed for the same copolymer over 10 cycles of repeated temperature change between 25°C (below the LCST) and 40°C (above the LCST).

A novel tripyridylporphyrin monomer, 5-[4-[2-(acryloyloxy)ethoxy]phenyl]-l0,l5,20-tris(4-pyridyl)porphyrin (TrPyP), was synthesized and polymerized with acrylamide (AM) to prepare the hydrophobically associating water-soluble polymer PAM-TrPyP. The aggregation behavior of porphyrin pendants was investigated by UV-Visible and fluorescence spectra. The polymer displays a strong tendency of hydrophobic association even in dilute solutions. With increasing the concentration, the maximum absorption wavelength of Soret band changes from 416 nm to 407 nm, and the fluorescence corrected for the inner filter effect exhibits moderate concentration quenching. All the results indicate that π-π interaction of porphyrin pendants plays a key role in association of PAM-TrPyP, and H-aggregates of porphyrins are mainly formed in the concentrated solution. On the other hand, dynamic light scattering (DLS) and transmission electron microscopy (TEM) were used to follow the changes in size and structure of the macromolecular assemblies with the concentration increase. The polymer aggregation conformation changes from loose “vesicle-like” morphology to solid globule accordingly. When pH value of solution decreases to 4.3, pyridine moieties on porphyrin pendants could be protonated and the H-aggregates formed in macromolecular matrix are destroyed by electrostatic repulsion interactions.

The novel porphyrin monomer 5-(4-acryloyloxylphenyl)-10,15,20-tris(4-carboxyphenyl)porphyrinate zinc(II) (ZnAOTCPP) and its corresponding sodium salt (ZnAOTCPP-Na) were synthesized. The latter compound exhibited a new band in excitation spectra due to formation of porphyrin aggregates in water, which were derived from its surface-activity when the concentration was higher than its critical association concentration (CAC). The porphyrins were copolymerized with acrylamide (AM) to prepare water-soluble copolymers with random and micro-blocky structures, which all displayed very new absorption and fluorescence emission bands in the long wavelength region compared with the porphyrin monomer. Furthermore, the micro-blocky copolymer exhibited an additional new absorption band at even longer wavelength region compared with the random copolymer. The experimental results and analysis showed that the porphyrin units in the random copolymer chains self-assembled to form porphyrin association complexes by hydrophobic association and π–π stacking interactions, and covalent restrictions of polymer chains in the micro-blocky copolymer.Highlights► The synthesis of novel tricarboxylphenyl porphyrin monomer and its corresponding sodium salt. ► The preparation of random copolymer and micro-blocky copolymer with porphyrins and acrylamide. ► The self-assembly of sodium salt of porphyrin monomer and copolymers in water. ► The characteristic absorption of porphyrin assemblies exhibiting at long wavelength region. ► The mimic light-harvesting system of water-soluble polymer containing porphyrins.

A series of polyethylene glycol-functionalized benzylidene cyclopentanone dyes with varying lipid/water partition coefficients were synthesized in high yields by a simple process. Detailed characterization and systematic studies of these molecules, including linear and nonlinear photophysical properties, reactive oxygen yields, and in vitro photodynamic therapy (PDT) activities, were conducted. Four of these dyes exhibited good solubility in PBS (>2 mg ml−1, which is sufficient for clinical venous injection), high reactive oxygen yields, large two-photon absorption and low dark toxicity, under the therapy dosage. Among them, two dyes could be absorbed efficiently by human rectal cancer 1116 cells, and presented strong two-photon excited PDT activity in in vitrocell experiments.

A novel oxazolidine based acid-labile monomer N-acryloyl-2,2-dimethyl-1,3-oxazolidine (ADMO) was synthesized and polymerized by reversible addition fragmentation chain transfer (RAFT) polymerization using poly(ethylene glycol) based chain transfer agent (PEG-CTA). The diblock copolymers PEG-b-PADMO were composed of hydrophilic PEG with fixed length and hydrophobic PADMO with different lengths, which formed core-shell micelles in water. Morphologies and sizes of micelles were obtained by transmission electron microscopy (TEM) and dynamic light scattering (DLS), which showed that the shapes of polymeric aggregates developed from small spherical micelles, worm-like micelles to larger size of vesicles, as the length of PADMO increased. The hydrolysis kinetics of the micelles was studied using 1H NMR, DLS and release of loaded Nile Red dye, whose rate strongly depended on pH and micellar structure. It led to the disruption of polymeric micelles and concomitant release of the guest molecules, due to the transformation of hydrophobic PADMO into hydrophilic poly(2-hydroxyethyl acrylamide) (PHEAM).

A novel tripyridylporphyrin monomer, 5-[4-[2-(acryloyloxy)ethoxy]phenyl]-10,15,20-tris(4-pyridyl)porphyrin (TrPyP), and its zinc (II) complex (ZnTrPyP) were synthesized. It was copolymerized with acrylamide to prepare water-soluble polymer P(ZnTrPyP-AM). The aggregation behavior of P(ZnTrPyP-AM) in aqueous solution was investigated by UV–visible absorption spectra. The red shift of Q band and the significantly enhanced relative intensity (ɛα/ɛβ) indicated that the ZnTrPyP was axially coordinated. Meanwhile, Soret band of porphyrin split into two bands, suggesting exciton coupling of aggregates. The porphyrin pendants of P(ZnTrPyP-AM) were supposed to form a slipped cofacial dimer and the macromolecular matrix helped to create the well-defined porphyrin aggregates. This finding was helpful for the assembly of artificial light-harvesting systems in aquatic environment to mimic the dimeric structure in natural LHC.Graphical abstractHighlights► We prepared zinc tripyridylporphyrin monomer and its water-soluble copolymers. ► Soret band of porphyrin pendants splits in copolymer with acrylamide. ► The porphyrin pendants form a slipped cofacial dimer in water. ► The porphyrin dimers dissociate with the addition of pyridine. ► The dimers formed in water-soluble polymer help to mimic the natural LHC.

A series of cationic surfmers with benzyl groups (QARBCs) with different R groups on the benzene ring were synthesized and characterized by IR, 1H-NMR, 13C-NMR. The aggregation of QARBCs was studied by the steady-state fluorescence technique. It turned out that QARBCs had surface activity and their critical micelle concentration (CMC) values varied in the range of 10−2–10−3 mol/L with slight increase with temperature. The copolymerization of acrylamide (M1) and QARBCs (M2) was studied below and above CMC, their reactivity ratios were determined by the Finemann-Ross method. It was found that below CMC, copolymerization took place in a homogeneous system and reactivity ratios of acrylamide and QARBCs were less than 1; while above CMC, reactivity ratios of QARBCs were greater than 1. The copolymerization mechanism of QARBC was observed to be similar to that of micellar polymerization. QARBCs tended to homopolymerization, which gave rise to micro-blocky sequences in the polymer backbone. The Q and e values of QARBCs were calculated according to the Alfrey-Price equation by using r1 (AM) and r2 (QARBC). Samples of poly(AM-co-QARBC) were prepared above and below CMC and their hydrophobic associations were studied by the steady-state fluorescence spectra and 2D NOESY spectra, and their critical associating concentrations (CAC) were estimated. The results showed that samples of poly(AM-co-QARBC) prepared above CMC had stronger hydrophobic association in aqueous solution than those prepared below CMC.

Benzylidene cyclopentanone dyes have high photosensitization activity and large two-photon absorption (TPA) cross-section in near infrared region. To explore their application potentials in two-photon excited photodynamic therapy (TPE-PDT), a series of carboxylate modified benzylidene cyclopentanone dyes were synthesized by varying number of carboxylate groups. Their linear and nonlinear photophysical properties, reactive oxygen yields and in vitro PDT activities were investigated systematically. The results showed that the water solubility of these dyes was significantly enhanced after introducing carboxylate groups. All dyes exhibited large TPA cross-section around 1000–1400 GM at 840 nm. In addition, they could generate both superoxide anion radical and singlet oxygen species under illumination. However, only the dye Y1 modified by one carboxylate group presented strong PDT activity to human rectal cancer 1116 cells, which indicated that moderate water–lipid amphipathy was a very important factor for PDT dyes. Finally, Y1 was proved to have large potential in TPE-PDT by in vitro experiments.Highlights► Four water soluble benzylidene cyclopentanone dyes were synthesized by introducing carboxylate group. ► All dyes could effectively generate reactive oxygen species through both Type I and Type II mechanisms. ► Their maximum TPA cross-sections were all above 1000 GM at 840 nm. ► The dye modified by only one carboxylate group presented strong one- and two-photon excited PDT activities to human rectal cancer 1116 cells. ► The water–lipid amphipathy is a very important factor to maintain the PDT activity of a dye.

Stimuli-responsive, well-defined diblock copolymers (PEG-b-PADMO) comprising poly(ethylene glycol) (PEG, DP (degree of polymerization) = 45) as the hydrophilic and temperature-sensitive part and poly(N-acryloyl-2,2-dimethyl-1,3-oxazolidine) (PADMO, DP = 18–47) as the hydrophobic and acid-labile part self-assembled in water into spherical micelles with high aggregation number. The micellar structures and thermally induced phase transitions of the copolymers were investigated with 1H NMR spectroscopy, light scattering, microscopy, turbidimetry, and fluorescence techniques. Thermoresponsive phase transitions of the copolymers in water were controlled via formation of core–shell-type micelles with densely compact PEG corona. Their lower critical solution temperatures (LCSTs) were modulated within the range 40–72 °C by varying PADMO block length. This unusually low LCST was attributed to the densely packed PEG structure in the polymer micelles, which resulted in strong n-clustering attractive interactions and insufficient hydration of PEG chains in the shell and greatly enhanced the thermosensitivity. The LCST behavior can also be modulated by partial acid hydrolysis of PADMO segments through the resulting change of hydrophobicity.

A series of hydrophobically associating polyacrylamides modified by small amounts (< 3 mol%) of a self-associative cationic monomer 4-(2-(acryloyloxy) ethoxy) benzyl tri-ethyl ammonium bromide (AEBA) as hydrophobe were synthesized by radical copolymerization in aqueous solutions without external surfactants. The resulting copolymers containing a multiblock structure exhibited a high tendency for hydrophobic association and a high thickening capacity. Solution properties and aggregation structures were investigated by viscometry and fluorescence technique. The high viscosity enhancement was found as the polymer concentration beyond a critical value c* and strongly depended on the copolymer microstructures. The number and length of hydrophobic microblocks within the copolymer backbones could be controlled by changing the AEBA concentration in copolymerization system. Addition of salt induced more hydrophobic association and viscosity enhancement. The synthesis method used was simple and environmentally friendly without any external surfactant contamination in comparison with the conventional micellar copolymerization.

One- and two-photon photophysical and photochemical properties of dyes 3-DAC and 4-DAC containing coumarin and benzylidene cyclopentanone moieties were studied. Their ground state configurations were optimized using both Hartree−Fock and density functional theory (B3LYP functional) methods, and excited-state properties were calculated using time-dependent density functional theory. These two dyes share the same formula and possess similar structures, except for different bridging positions between the benzylidene cyclopentanone and coumarin moieties. The bridging position was found to have a significant effect on the electronic structure and photophysical and photochemical properties of the dyes. 3-DAC shows higher conjugation and is more planar than 4-DAC, and it exhibits a larger TPA cross section. In contrast, 4-DAC has a twisted conformation, exhibits a lower electron transfer free energy with initiator and shows higher sensitizing efficiencies in one-photon polymerization. Furthermore, the application potential of 3-DAC and 4-DAC in two-photon polymerization (TPP) was studied. Both dyes could be used directly as initiators in TPP. The TPP threshold energies of the corresponding resins were as low as the best reported results. High-resolution 2D and 3D nanopatterns containing low amounts of small molecule residue were successfully fabricated by TPP, demonstrating the extensive application prospects of these dyes in the fabrication of micromachines, microsensor arrays and biomedical devices.

A feasible methodology for the preparation of vesicles through self-assembly of supramolecular graft copolymers (SGPs) was developed. Two types of polymeric vesicles were prepared through self-assembly of two SGPs. For the first SGP, hydrophobic poly(4-vinylpyridine) (PVPy) were used as main chains, and hydrophilic poly(N-vinylpyrrolidone) with carboxylic end groups (PNVP-COOH) were grafted onto the main chains through ionic interaction between the carboxylic groups and pyridine groups. For the second SGP, hydrophobic poly(4-acrylamidobenzoic acid) (PABA) were used as main chains, and poly(N-vinylpyrrolidone) with amino end groups were grafted onto the main chains through ionic interaction between the amino groups and carboxylic groups. Both SGPs could self-assemble to form vesicles in aqueous solution. The size of the vesicles prepared from the PVPy/PNVP-COOH (or PABA/PNVP-NH2) system could be controlled through modulation of the mass ratio of PVPy and PNVP-COOH (or PABA and PNVP-NH2). Both vesicles were sensitive to pH and could be deformed by changing pH. Drug-release studies showed that release rates of the loaded drug (sunset yellow) in the two vesicles could be well-controlled by the pH of the releasing solution.

A series of multibranched benzylidene cyclopentanone dyes with non-conjugated central moiety were synthesized. Their one- and two-photon photophysical properties were systematically studied in comparison with corresponding triphenylamine derivatives. Electronic coupling and vibronic coupling contributions to cooperative enhancement of two-photon absorption in multibranched structure were revealed. The results showed that the crucial contribution for this enhancement was from electronic coupling effect among branches. In addition, no contribution of vibronic coupling was observed. Furthermore, multibranched effect on photosensitizing efficiency of these compounds was investigated by one-photon polymerization and the result indicated the electronic coupling effect was also beneficial to their photosensitizing efficiency.

A novel water-soluble benzylidene cyclopentanone dye was synthesized by introducing four sodium carboxylate groups into 2,5-Bis-[4-(diethylamino)-benzylidene]-cyclopentanone (BDEA). Its two-photon absorption (TPA) cross-section in water solution was determined by nonlinear transmission method with Ti:sapphire femtosecond laser as exciting light source. 287 GM at 800 nm was obtained, which was quite larger than TPA cross-section of water-soluble xanthene dyes. Using this new dye as initiator, two-photon polymerization (TPP) of water-soluble acrylate could be induced directly. Low threshold energy of 0.51 mW and a high resolution of 400 nm were achieved, indicating this dye would have extensive application prospects in TPP under aqueous environments.

Five, asymmetrical benzylidene cyclopentanone dyes were synthesized and their one- and two-photon photophysical properties were investigated. Measurements revealed that the two-photon absorption cross-sections (TPACS) of these compounds in chloroform were of the order of 10−48 cm4 s molecule−1 photon−1 in the wavelength range 700–880 nm. The sensitizing efficiencies of the dyes in photopolymerization systems were also considerable and matching those of the commercial initiator o-Cl-hexaarylbisimidazoles (HABI). The two-photon polymerization results proved that these photosensitizers possess large potential for two-photon absorption induced polymerization.

Polymeric vesicles were prepared through self-assembly of amphiphilic supramolecular block copolymers (SBP). Hydrophilic poly(N-isopropylacrylamide) with amino end groups (PNIPAM-NH2) and hydrophobic polystyrene with carboxylic end groups (PSt-COOH) were prepared by free radical polymerization using cysteamine hydrochloride and thioglycolic acid as chain transfer reagents, respectively. These two polymer chains could be connected through the ionic interaction of the amino groups and carboxylic groups in dioxane to form an amphiphilic SBP. The self-assembly behavior of SBP was investigated in dioxane/H2O and dioxane/ethanol systems. In the dioxane/H2O system, these amphiphilic SBP could self-assemble to form spherical vesicles. In the dioxane/ethanol system, the morphologies of the formed aggregates were dependent on the SBP concentration. As the SBP concentration increased from 0.01 to 0.075 g mL−1, the aggregates changed from wormlike vesicles to spherical vesicles. A temperature-induced morphological transition was observed in the dioxane/ethanol system. Increasing the temperature of the wormlike vesicular solution led to the transformation of the aggregates from wormlike vesicles to spherical vesicles.

A series of ketocoumarin derivatives were synthesized using Aldol condensation and Wittig reactions and their one- and two-photon photophysical properties were investigated. Two-photon absorption cross-sections (δ) of the derivatives revealed that most of the new compounds possessed δ values that were some one to two orders of magnitudes larger than those of commercial coumarin dyes. The largest δ value within measured range was obtained as 1570 GM, which is comparable to that of reported strong two-photon absorption compounds. These novel derivatives containing the functional ketocoumarin group should open new opportunities for two-photon polymerization.

Two malononitrile derivatives, 2-[2,5-bis-(4-dimethylamino-benzylidene)-cyclopentylidene]-malononitrile (1) and 2-{2,6-bis-[2-(4-dimethylamino-phenyl)-vinyl]-pyran-4-ylidene}-malononitrile (2), were synthesized and their photophysical characteristics were investigated using UV–vis spectra, fluorescence spectra, nonlinear transmission and two-photon excited spectra. The results showed that both compounds exhibited strong intramolecular charge transfer absorption bands within 400–600 nm, but only compound 2 presented a strong fluorescence emission. By nonlinear transmission method, the two-photon absorption cross-section (σ) values of two compounds were determined as 250 GM and 283 GM, respectively, with 800 nm femtosecond laser pulses. By two-photon excited fluorescence method, the two-photon excited spectra of compound 2 within 720–880 nm was measured and its σmax was obtained as 773 GM at 770 nm.

The association and properties of multi-block like copolymers (TP) of acrylamide(AM) and acrylic acid (AA) prepared by template copolymerization in aqueous solution were studied. The results showed that the copolymers of this type exhibited a significant structure effect compared with that of similar random copolymers (CP) obtained by copolymerization in the absence of template. Decreasing the value of pH or adding Ca2+ ion to the copolymer solution will make phase separation occur. The TEM images demonstrated that the phase separation caused by Ca2+ ion was due to the formation of extensively intermolecular cross-linking. With the increase of the pH value of copolymer solution, the changes of the solution viscosity was similar with that of homopolyacrylic acid, which originally increased and then decreased. But the increase range of template copolymer was higher than that of homopolyacrylic acid. TEM images indicated that at the maximal viscosity the copolymer obtained in the presence of template formed coiled aggregates.

Multibranched benzylidene cyclopentanone dyes with a triphenylamine core were synthesized. Their two-photon optical properties were characterized using a Ti:sapphire femtosecond laser. The results showed that the two-photon absorption cross-sections (δ) of these compounds were increased with increasing numbers of branches. The largest δ value of the three-branched compound 3 was 3298 GM which was almost six times larger than that of a model compound, 2,5-bis-[4-(dimethylamino)benzylidene]cyclopentanone (BDMA). The sensitizing efficiencies of three new dyes in photopolymerization systems were all higher than that of BDMA matching with the commercial initiator 4,4′-dimethyldiphenyliodinium hexafluorophosphate (Omnicat 820). The two-photon polymerization initiated by the bimolecular system composed of compound 3 and Omnicat 820 was investigated under femtosecond laser pulses.

A series of polyethylene glycol-functionalized benzylidene cyclopentanone dyes with varying lipid/water partition coefficients were synthesized in high yields by a simple process. Detailed characterization and systematic studies of these molecules, including linear and nonlinear photophysical properties, reactive oxygen yields, and in vitro photodynamic therapy (PDT) activities, were conducted. Four of these dyes exhibited good solubility in PBS (>2 mg ml−1, which is sufficient for clinical venous injection), high reactive oxygen yields, large two-photon absorption and low dark toxicity, under the therapy dosage. Among them, two dyes could be absorbed efficiently by human rectal cancer 1116 cells, and presented strong two-photon excited PDT activity in in vitrocell experiments.

Thermosensitive poly(N-isopropylacrylamide) (PNIPAM) semi-hollow spheres consisting of low density cores, dense shells and separated cavities between cores and shells were prepared via two-step precipitation polymerization. The self-cross-linked poly(N-isopropylacrylamide-co-methacrylic acid) (PNIPAM-co-PMAA) gels with low solid density were prepared in the first precipitation polymerization and served as the templates on which dense PNIPAM shells cross-linked by N,N′-methylenebis(acrylamide) (BMA) were formed in the second precipitation polymerization. The shell thickness of the semi-hollow spheres could be controlled via adjusting the feeding core/shell mass ratios. The carboxylic groups on the core were conjugated with doxorubicin (DOX) via disulfide bonds which could be degraded by the reduction of glutathione (GSH). The release of DOX from the cores could be controlled by temperature and shell thickness with the disulfide bonds degraded by GSH. The cell viability assay indicated that the semi-hollow particles conjugated with DOX by disulfide bonds showed remarkable toxicity to Hela cells, and the toxicity was related to the shell thickness of the particles.

A series of bis(arylidene)cycloalkanone compounds based on cyclobutanone, cyclopentanone, cyclohexanone and cycloheptanone, C4–C7, respectively, with a D-π-A-π-D structure containing the same donor and acceptor but different alicyclic rings was prepared. The effects of alicyclic ring size on the photophysical, photochemical and electrochemical properties of these compounds were investigated systematically. We found that an increase of the number of carbons in the central alicyclic ring leads to changes in geometry, which has significant effects on the conjugation, and photophysical and photochemical properties. These effects include decreases in the fluorescence quantum yield, transient lifetimes, peak extinction coefficients, and the singlet oxygen quantum yield with the increase of the ring size. The one-photon absorption spectra, the two-photon absorption (2PA) spectra, and the fluorescence spectra all show a hypsochromic shift with increasing ring size. The results of this study provide guidance for the design of new cycloketone-based D-π-A-π-D 2PA compounds for photopolymerization and photodynamic therapy applications.