GSH/pH Cascade-Responsive Nanoparticles Eliminate Methicillin-Resistant Staphylococcus aureus Biofilm via Synergistic Photo-Chemo Therapy.

Bacterial biofilm infection threatens public health, and efficient treatment strategies are urgently required. Phototherapy is a potential candidate, but it is limited because of the off-targeting property, vulnerable activity, and normal tissue damage. Herein, cascade-responsive nanoparticles (NPs) with a synergistic effect of phototherapy and chemotherapy are proposed for targeted elimination of biofilms. The NPs are fabricated by encapsulating IR780 in a polycarbonate-based polymer that contains disulfide bonds in the main chain and a Schiff-base bond connecting vancomycin (Van) pendants in the side chain (denoted as SP-Van@IR780 NPs). SP-Van@IR780 NPs specifically target bacterial biofilms in vitro and in vivo by the mediation of Van pendants. Subsequently, SP-Van@IR780 NPs are decomposed into small size and achieve deep biofilm penetration due to the cleavage of disulfide bonds in the presence of GSH. Thereafter, Van is then detached from the NPs because the Schiff base bonds are broken at low pH when SP@IR780 NPs penetrate into the interior of biofilm. The released Van and IR780 exhibit a robust synergistic effect of chemotherapy and phototherapy, strongly eliminate the biofilm both in vitro and in vivo. Therefore, these biocompatible SP-Van@IR780 NPs provide a new outlook for the therapy of bacterial biofilm infection.

Cascade-Targeting Poly(amino acid) Nanoparticles Eliminate Intracellular Bacteria via On-Site Antibiotic Delivery.

Intracellular bacteria in latent or dormant states tolerate high-dose antibiotics. Fighting against these opportunistic bacteria has been a long-standing challenge. Herein, the design of a cascade-targeting drug delivery system (DDS) that can sequentially target macrophages and intracellular bacteria, exhibiting on-site drug delivery, is reported. The DDS is fabricated by encapsulating rifampicin (Rif) into mannose-decorated poly(α-N-acryloyl-phenylalanine)-block-poly(ß-N-acryloyl-d-aminoalanine) nanoparticles, denoted as Rif@FAM NPs. The mannose units on Rif@FAM NPs guide the initial macrophage-specific uptake and intracellular accumulation. After the uptake, the detachment of mannose in acidic phagolysosome via Schiff base cleavage exposes the d-aminoalanine moieties, which subsequently steer the NPs to escape from lysosomes and target intracellular bacteria through peptidoglycan-specific binding, as evidenced by the in situ/ex situ co-localization using confocal, flow cytometry, and transmission electron microscopy. Through the on-site Rif delivery, Rif@FAM NPs show superior in vitro and in vivo elimination efficiency than the control groups of free Rif or the DDSs lacking the macrophages- or bacteria-targeting moieties. Furthermore, Rif@FAM NPs remodel the innate immune response of the infected macrophages by upregulating M1/M2 polarization, resulting in a reinforced antibacterial capacity. Therefore, this biocompatible DDS enabling macrophages and bacteria targeting in a cascade manner provides a new outlook for the therapy of intracellular pathogen infection.

Catalytic hydrothermal liquefaction of Gracilaria corticata macroalgae: Effects of process parameter on bio-oil up-gradation.

Hydrothermal liquefaction (HTL) of Gracilaria corticata (GC) macroalgae was studied over a series of nickel-iron-layered double oxides (NiFe-LDO) supported on activated bio-char catalysts at 280 °C and different solvents medium. Maximum bio-oil yield (56.2 wt%) was found with 5%Ga/NiFe-LDO/AC catalyst at 280 °C under ethanol solvent. The catalytic HTL up-gradation decreased the bio-char yield significantly. However the bio-oil quality significantly improved with using the 5%Ga/NiFe-LDO/AC catalyst. Also, improved performance with higher amount of bio-oil and lower amounts of bio-char and gas were achieved, which is due the several reactions happening during the HTL process. Catalytic HTL also revealed that introducing NiFe-LDO nanosheets into the activated char could result in NiFe-LDO/AC catalysts of higher surface area and increased active sites. Being impregnated by 5%Ga, catalysts with improved acid sites and thereby, advanced deoxygenation and aromatization activities were achieved. Hence Ga/NiFe-LDO/AC could be considered as a promising catalyst HTL bio-oil upgrading.

PdIrBP mesoporous nanospheres combined with superconductive carbon black for the electrochemical determination and collection of circulating tumor cells.

An integrated electrochemical immunoassay is described for the determination of circulating tumor cells (CTCs). For the first time, Ketjen black (KB), which is a superconductive carbon material, was incorporated with Au nanoparticles (AuNPs) and used to modify the surface of gold electrodes. A cocktail of anti-epithelial cell adhesion molecules (EpCAM) and anti-vimentin antibodies was chosen to capture the CTCs. Palladium-iridium-boron-phosphorus alloy-modified mesoporous nanospheres (PdIrBPMNS) served as a catalytic tag to amplify the current signal. Glycine-HCl (Gly-HCl) was used as an antibody eluent to release and collect the captured CTCs from the electrodes for further clinical research without compromising cell viability. The response of the method increased linearly from 10 to 1 × 106 cells mL-1 CTCs, while the detection limit was calculated to be as low as 2 cells mL-1. This method was successfully used to determine CTCs in spiked blood samples and demonstrated good recovery. Graphical abstractKetjen black/AuNPs was incorporated in the electrochemical platform to enhance the electron transfer ability of the electrode surface. PdIrBP mesoporous nanospheres were used to amplify DPV signal in this assay. The introduction of Gly-HCl realized nondestructive recovery of circulating tumor cells.

Colorimetric determination of BCR/ABL fusion genes using a nanocomposite consisting of Au@Pt nanoparticles covered with a PAMAM dendrimer and acting as a peroxidase mimic.

A colorimetric assay is described for the detection of BCR/ABL fusion genes. Polyamidoamine (PAMAM) dendrimers were placed on peroxidase (POx) mimicking Au@Pt nanoparticles to form a nanocomposite of type Au@Pt-PAMAM. Capture DNA probe is a designed nucleic acid strand that specifically binds target DNA to the surface of the electrode. The capture probe was attached to magnetic beads via biotin and avidin interaction. The hairpin structure of the capture probe can only be opened by the complementary BCR/ABL DNA. This results in a highly specific assay. The POx-mimicking property of the Au@Pt-PAMAM causes the formation of a blue dye by reaction of H2O2 and 3,3,3',3'-tetramethylbenzidine (TMB) which is measured by a microplate reader. Under optimum conditions, the absorbance increases linearly the 1 pM to 100 nM BCR/ABL concentration range, and the detection limit is as low as 190 fM. The method is highly selective and was successfully applied to the determination of fusion genes in spiked real samples. Conceivably, it possesses a large potential in clinical testing of patients suffering from chronic myeloid leukemia. Graphical abstract Au@PtNP, an efficient catalyst, is bound with polyamidoamine (PAMAM) dendrimer to amplify the colorimetric signal. With the introduction of streptavidin-magnetic beads to remove non-specific signals, a novel colorimetric sensor is constructed to detect BCR/ABL fusion genes.

[Effects of Sinopodophyllum hexundrum on apoptosis in K562 cells].

OBJECTIVE: To investigate the effects of Sinopodophyllum hexundrum on apoptosis in K562 cells. METHODS: K562 cells were treated with Sinopodophyllum hexundrum at different concentrations and for different lengths of time to determine the optimal conditions of SinoPodophyllum hexandrum treatment for K562 cells using CCK8 assay. The cell apoptotic rate was detected by flow cytometry, and the cell morphology and nuclear morphology of K562 cells were observed with Wright staining and DPAI staining, respectively. The protein expressions of BCR/ABL, p-BCR/ABL, STAT5, p-STAT5 and the apoptosis-related proteins PARP, caspase-3 and cleaved-caspase-3 were determined with Western blotting. RESULTS: The cell proliferation was inhibited in a concentration-and time-dependent manner by 1, 2, and 3 µg/mL Sinopodophyllum hexundrum. The treatment was optimal with a Sinopodophyllum hexundrum concentration of 2 µg/mL a treatment time of 48 h, and the cell apoptotic rate increased in a time-dependent manner and significantly increased at 48 h (P<0.001). The expression of apoptosis-related proteins PARP, caspase-3 and cleaved-caspase-3 were also activated in a time-dependent manner. The cells showed typical apoptotic changes after treatment with 2 µg/mL Sinopodophyllum hexundrum for 48 h with significantly reduced expressions of BCR/ABL, p-BCR/ABL, STAT5, AND p-STAT5. CONCLUSION: Sinopodophyllum hexundrum promotes K562 cell apoptosis possibly by inhibiting BCR/ABL-STAT5 survival signal pathways and activating the mitochondrion-associated apoptotic pathways.

TAT-CC fusion protein depresses the oncogenicity of BCR-ABL in vitro and in vivo through interrupting its oligomerization.

Chronic myeloid leukemia (CML) is a clonal hematologic malignancy characterized by the BCR-ABL protein. BCR-ABL is a constitutively active tyrosine kinase and plays a critical role in the pathogenesis of CML. Imatinib mesylate, a selective tyrosine kinase inhibitor, is effective in CML, but drug resistance and relapse occur. The coiled-coil (CC) domain located in BCR(1-72) mediates BCR-ABL tetramerization, which is essential for the activation of tyrosine kinase and transformation potential of BCR-ABL. CC domain is supposed to be a therapeutic target for CML. We purified a TAT-CC protein competively binding with the endogenous CC domain to reduce BCR-ABL kinase activity. We found that TAT-CC co-located and interacted with BCR-ABL in Ba/F3-p210 and K562 cells. It induced apoptosis and inhibited proliferation in these cells. It increased the sensitivity of these cells to imatinib and reduced the phosphorylation of BCR-ABL, CRKL and STAT5. We confirmed that TAT-CC could attenuate the oncogenicity of Ba/F3-p210 cells and diminish the volume of K562 solid tumor in mice. We conclude targeting the CC may provide a complementary therapy to inhibit BCR-ABL oncogenicity.