Topological Fracton Quantum Phase Transitions by Tuning Exact Tensor Network States.

Gapped fracton phases of matter generalize the concept of topological order and broaden our fundamental understanding of entanglement in quantum many-body systems. However, their analytical or numerical description beyond exactly solvable models remains a formidable challenge. Here we employ an exact 3D quantum tensor-network approach that allows us to study a Z_{N} generalization of the prototypical X cube fracton model and its quantum phase transitions between distinct topological states via fully tractable wave function deformations.

SU(3)_{1} Chiral Spin Liquid on the Square Lattice: A View from Symmetric Projected Entangled Pair States.

Quantum spin liquids can be faithfully represented and efficiently characterized within the framework of projected entangled pair states (PEPS). Guided by extensive exact diagonalization and density matrix renormalization group calculations, we construct an optimized symmetric PEPS for a SU(3)_{1} chiral spin liquid on the square lattice. Characteristic features are revealed by the entanglement spectrum (ES) on an infinitely long cylinder.

Carbon nanodots featuring efficient FRET for two-photon photodynamic cancer therapy with a low fs laser power density.

The 5,10,15,20-tetrakis(1-methyl 4-pyridinio) porphyrins (TMPyP), a photosensitizer used for photodynamic therapy of cancers (PDT), were linked to carbon dots (CDots) to form the conjugates of CDot-TMPyP by the electrostatic force. The 415 nm emission band of CDots was well overlapped with the absorption band of TMPyP, so that the Cdots in conjugates can work as donor to transfer the energy to TMPyP moiety by fluorescence resonance energy transfer (FRET) with an FRET efficiency of 45%, determined by the fluorescence lifetime change between the free CDots and conjugated CDots. The two-photon absorption cross section (TPACS) of TMPyP is as low as 110 GM and the TMPyP thus be not suitable for two-photon PDT.

The aggregation enhanced photoluminescence of gold nanorods in aqueous solutions.

The photoluminescence (PL) properties of single gold nanorod (AuNR) under one-photon excitation (OPE) have been reported recently. In this work, the PL of AuNRs in aqueous solutions were studied with OPE of 514 or 633 nm to characterize the emissions of transverse and longitudinal surface Plasmon resonance (TSPR and LSPR) bands, because the AuNRs aqueous solution was frequently used in bio-medical applications. We found that under 514 nm OPE the TSPR emissions of four groups of AuNRs with different aspect ratios in aqueous solutions were all strong dominating the PL emission with the quantum yield (QY) of 10(-4), which is at least three orders of magnitude higher than that of single AuNR.

One-step synthesis of water-dispersible silicon nanoparticles and their use in fluorescence lifetime imaging of living cells.

We report a novel method for synthesizing water-dispersible silicon nanoparticles (Si NPs) with a simple one-step procedure using mild reagents (3-aminopropyl) trimethoxysilane (APTES) and ascorbate sodium (AS). This is the first report of "green" synthesis of Si NPs on a large scale and at low cost. The method involves a quick reaction in a commonly used round bottom flask at room temperature and pressure without additional treatment and any special equipment.

Two orders of magnitude fluorescence enhancement of aluminum phthalocyanines by gold nanocubes: a remarkable improvement for cancer cell imaging and detection.

The metal-enhanced fluorescence (MEF) by metal nanoparticles is a useful technique for fluorescence detections in biological systems. The MEF effects with gold nanorods (AuNRs) and nanocubes (AuNCs) for fluorescence enhancements of sulfonated aluminum phthalocyanine (AlPcS), a commonly used and clinical approved photosensitizer for photodynamic therapy of cancers, were studied in this work. For the AuNRs which have the low aspect ratios with the corresponding longitudinal surface plasma resonance (LSPR) band in the region of 600-750 nm, the fluorescence quenching of conjugated AlPcS was found.

Conjugates of folic acids with zinc aminophthalocyanine for cancer cell targeting and photodynamic therapy by one-photon and two-photon excitations.

To improve the photodynamic detection and therapy of cancers (PDT), folic acid (FA) was conjugated with zinc tetraaminophthalocyanine (ZnaPc) to form ZnaPc-FA. The uptake efficiency of ZnaPc-FA to a FR-positive (folate receptor overexpressed) KB cell line (human nasopharyngeal epidermal carcinoma) was much higher than that of ZnaPc demonstrating an enhanced binding ability of ZnaPc-FA to KB cells. When KB cells were pretreated with free FA followed by incubation of ZnaPc-FA, the high uptake rate of ZnaPc-FA disappeared which demonstrated the special binding function of the FA terminal of ZnaPc-FA on KB cells.

Study of polycation-capped Mn:ZnSe quantum dots as a novel fluorescent probe for living cells.

Transition metal manganese ion (Mn(2+)) doped zinc selenide quantum dots (Mn:ZnSe D-Dots) have been considered as a new material for fluorescent probes in biological labeling. However, this application is limited by the low membrane permeability of D-Dots. In this work, Mn:ZnSe D-Dots were capped with the polycation Sofast to label living cells.

Femto-second laser beam with a low power density achieved a two-photon photodynamic cancer therapy with quantum dots.

Focusing the femto-second (fs) laser beam on the target was the usual way to carry out a two-photon excitation (TPE) in previous photodynamic therapy (PDT) studies. However, focusing the laser deep inside the tissues of the tumor is unrealistic due to tissue scattering, so that this focusing manner seems unfit for practical TPE PDT applications. In this work, we prepared a conjugate of quantum dots (QDs) and sulfonated aluminum phthalocyanine (AlPcS) for TPE PDT, because QDs have a very high two-photon absorption cross section (TPACS) and thus QDs can be excited by an unfocused 800 nm fs laser beam with a low power density and then transfer the energy to a conjugated AlPcS via fluorescence resonance energy transfer (FRET).

The use of femto-second lasers to trigger powerful explosions of gold nanorods to destroy cancer cells.

Gold nanorods (AuNRs) with an aspect ratio of 3-4 exhibit large cross sections for single and multi photon light absorption processes in the near infrared region due to surface plasmon resonances. 800 nm laser pulses with the 150 fsec pulse duration (fs laser) can trigger explosions of AuNRs. The fs laser pulses at 20 W/mm(2) equivalent continuous wave (cw) power density blasted AuNRs in QGY human carcinoma cells as confirmed using transmission electron microscopy, while a cw laser at the same power density and dose did not.

The conjugates of gold nanorods and chlorin e6 for enhancing the fluorescence detection and photodynamic therapy of cancers.

Gold nanorods (AuNRs) were conjugated with chlorin e6 (Ce6), a commonly used photosensitizer, to form AuNRs-Ce6 by electrostatic binding. Due to the strong surface plasmon resonance coupling, the fluorescence of conjugated Ce6 was enhanced 3-fold and the production of singlet oxygen was increased 1.4-fold.

Comparison of the killing effects between nitrogen-doped and pure TiO2 on HeLa cells with visible light irradiation.

The killing effect of nitrogen-doped titanium dioxide (N-TiO2) nanoparticles on human cervical carcinoma (HeLa) cells by visible light photodynamic therapy (PDT) was higher than that of TiO2 nanoparticles. To study the mechanism of the killing effect, the reactive oxygen species produced by the visible-light-activated N-TiO2 and pure-TiO2 were evaluated and compared. The changes of the cellular parameters, such as the mitochondrial membrane potential (MMP), intracellular Ca2+, and nitrogen monoxide (NO) concentrations after PDT were measured and compared for N-TiO2- and TiO2-treated HeLa cells.

Conjugation of sulfonated aluminum phthalocyanine to doxorubicin can improve the efficacy of photodynamic cancer therapy.

Sulfonated aluminum phthalocyanine (AlPcS), a widely used photosensitizer for photodynamic therapy of cancer, was conjugated to doxorubicin (Dox), a chemotherapy drug, through electrostatic binding. The fluorescence resonance energy transfer from Dox to AlPcS showed the formation of AlPcS-Dox conjugates, as the fluorescence intensity of conjugated Dox was decreased and that of the AlPcS moiety was enhanced. This AlPcS-Dox conjugation was further confirmed by electrophoresis.

Quantum dot-aluminum phthalocyanine conjugates perform photodynamic reactions to kill cancer cells via fluorescence resonance energy transfer.

Sulfonated aluminum phthalocyanines (AlPcSs), commonly used photosensitizers for photodynamic therapy of cancers (PDT), were conjugated with amine-dihydrolipoic acid-coated quantum dots (QDs) by electrostatic binding, achieving 70 AlPcSs per QD. The AlPcS-QD conjugates can utilize the intense light absorptions of conjugated QDs to indirectly excite AlPcSs producing singlet oxygen via fluorescence resonance energy transfer (FRET), demonstrating a new excitation model for PDT. The AlPcS-QD conjugates easily penetrated into human nasopharyngeal carcinoma cells and carried out the FRET in cells, with efficiency around 80%.

Gallium phthalocyanine photosensitizers: carboxylation enhances the cellular uptake and improves the photodynamic therapy of cancers.

The octacarboxyl gallium (GaPcC) and metal-free (H2PcC) phthalocyanines were prepared using the carboxyl as the peripheral substituent. The carboxylation improves the intracellular delivery of these two PcCs into KB and QGY cancer cells as compared to that of sulfonated aluminum phthalocyanines (AlPcS), a popularly used photosensitizer (PS). Moreover, GaPcC maintains high photoproduction of singlet oxygen.

Study on the visible-light-induced photokilling effect of nitrogen-doped TiO2 nanoparticles on cancer cells.

Nitrogen-doped TiO2 (N-TiO2) nanoparticles were prepared by calcining the anatase TiO2 nanoparticles under ammonia atmosphere. The N-TiO2 showed higher absorbance in the visible region than the pure TiO2. The cytotoxicity and visible-light-induced phototoxicity of the pure- and N-TiO2 were examined for three types of cancer cell lines.

Liposome encapsulation of thiol-capped CdTe quantum dots for enhancing the intracellular delivery.

Although water soluble thiol-capped quantum dots (QDs) have been widely used as photoluminescence (PL) probes in various applications, the negative charges on thiol terminals limit the cell uptake hindering their applications in cell imaging. The commercial liposome complex (Sofast®) was used to encapsulate these QDs forming the liposome vesicles with the loading efficiency as high as about 95%. The cell uptakes of unencapsulated QDs and QD loaded liposome vesicles were comparatively studied by a laser scanning confocal microscope.

Enhancement of intracellular delivery of anti-cancer drugs by the Tat peptide.

The arginine-rich cationic Tat peptides have been reported to enhance the intracellular delivery of macromolecules, including DNA, RNA, and proteins. In this work an arginine cationic peptide derived from the HIV-1 Tat protein was conjugated with noncovalent bonds to sulfonated aluminum phthalocyanine (AlPcS, a photosensitizer for the light-activated photodynamic cancer therapy), doxorubicin (DOX, a chemotherapeutic agent), or quantum dots (QDs, often used as carriers for the delivery of anticancer drugs). The fluorescence of intracellular conjugates of AlPcS-Tat, DOX-Tat, and QDs-Tat was studied by means of confocal laser scanning microscopy in the human nasopharyngeal carcinoma KB cells and cervical carcinoma Hela cells in vitro.

Plasmonic gold nanorods can carry sulfonated aluminum phthalocyanine to improve photodynamic detection and therapy of cancers.

Hexadecyltrimethylammonium bromide-coated gold nanorods (AuNRs) with positive charges were effectively bound to negatively charged sulfonated aluminum phthalocyanine (AlPcS), a photosensitizer for photodynamic detection and therapy, due to the electrostatic force, with a loading content of 10(4) AlPcS molecules per rod. A 5-fold increase in the AlPcS fluorescence of the AlPcS-AuNRs complex was seen. The excitation fluorescence spectrum of the AlPcS-AuNRs with a typical 520 nm band fits well with the resonance band of AuNR surface plasmons, suggesting that such increased AlPcS fluorescence is produced from the strong surface plasmons of AuNRs.

Conjugates of folic acids with BSA-coated quantum dots for cancer cell targeting and imaging by single-photon and two-photon excitation.

Bovine serum albumin (BSA)-coated CdTe/ZnS quantum dots (BSA-QDs) were selected to conjugate with folic acid (FA), forming FA-BSA-QDs. This study aims to develop these small FA-BSA-QDs (less than 10 nm) for the diagnosis of cancers in which the FA receptor (FR) is overexpressed. The enhancement of cellular uptake in FR-positive human nasopharyngeal carcinoma cells (KB cells) for FA-BSA-QDs was found by means of confocal fluorescence microscopy under single-photon and two-photon excitation.

Mitochondrial signaling for histamine releases in laser-irradiated RBL-2H3 mast cells.

Background: The low power laser irradiation (LPLI) can promote the wound healing, but the mechanism is still not fully understood. We have found in our previous work that the LPLI induces mast cells to release the histamine and thus suggested that the increased histamine release is probably one of the causes for promoting the wound healing since mast cells have been found to play positive roles in the process of wound healing. This study aims to explore the mechanism of histamine release in RBL-2H3 mast cells under laser irradiations.

Study on the intracellular fate of Tat peptide-conjugated quantum dots by spectroscopic investigation.

The photoluminescence (PL) spectrum of water-soluble thiol-capped CdTe quantum dots (QDs) conjugated with Tat peptide in solution showed a remarkable redshift as compared to that of unconjugated QDs. After cellular uptake of the Tat-QDs conjugates, the micro-PL spectrum of Tat-QDs in lysosomes showed a spectral blueshift, which was most probably due to the fact that Tat peptide was digested by the enzymes, leaving the Tat-detached QDs in lysosomes. The reasons for the spectral changes have been discussed in detail.

Quantum dot-mediated photoproduction of reactive oxygen species for cancer cell annihilation.

While semiconductor quantum dots produce little singlet oxygen, they may undergo Type I photoreactions to produce other reactive oxygen species (ROS) to kill cells. CdTe quantum dots coated with thioglycolic acid were used to test that possibility. Some thiol ligands were purposely removed to regenerate the surface electron traps that were passivated by the ligand.

Poly (N-isopropylacrylamide)-coated multifunctional nanoparticles for cell tracking.

Objective: The objective of this work was to explore a new modality of cell tracking that uses multifunctional nanoparticles. The tracking of transfused cells in vivo is an important step to study the therapeutic course and mechanism of cell therapeutics.

Background Data: Several methods of cell tracking have been developed.

Fast transfection of mammalian cells using superparamagnetic nanoparticles under strong magnetic field.

Through the use of superparamagnetic iron oxide nanoparticles (SPIONs), fast delivery of DNA into adherent and suspended cells could be achieved by the mediation of a strong impulsed magnetic field. Mammalian cells were well transfected with enhanced green fluorescent protein gene. To mediate the cellular uptake, cells and nucleic acid complexes were mixed together and exposed once or several times to impulsed magnetic field for short durations of few milliseconds.