Cumulative Release Rate Research Articles

Preparation of Gd-doped AuNBP@mSiO2 nanocomposites for the MR imaging, drug delivery and chemo-photothermal synergistic killing of breast cancer cells.

Under near-infrared (NIR) light, gold nanobipyramids (AuNBPs) exhibit a high photothermal conversion rate and photothermal stability, making them ideal mediators for photothermal therapy (PTT). In this study, highly purified AuNBPs are prepared, followed by coating their surfaces with mesoporous silica (mSiO2). The obtained AuNBP@mSiO2 nanocomplex exhibits an ellipsoidal shape with a relatively large specific surface, pore diameter and pore volume. To achieve MRI guided chemo-photothermal therapy of breast cancer cells, the nanocomplex is further coupled with the MRI contrast agent Gd-DTTA and the chemotherapeutic drug doxorubicin (DOX). The results indicated that under NIR light irradiation, AuNBPs exhibited promising PTT effects, while the cumulative release rate of DOX was significantly enhanced to 81.40%. Moreover, the chemo-photothermal therapy approach effectively eradicated 4T1 breast cancer cells. This work successfully confirms that chemo-photothermal synergistic therapy is an effective tumor treatment strategy and demonstrates the potential application of AuNBP@mSiO2 as a nano-drug delivery platform. Additionally, it introduces new ideas for the integrated study of breast cancer diagnosis and treatment.

An injectable and pH-responsive hyaluronic acid hydrogel as metformin carrier for prevention of breast cancer recurrence

To achieve the pH-responsive release of metformin in tumor acidic microenvironment, we prepared OHA-Met by covalently grafting metformin (Met) onto oxidized hyaluronic acid (OHA) through imine bonds, and then prepared carboxymethyl chitosan (CMCS)/OHA-Met drug loaded hydrogels. The CMCS/OHA-Met hydrogels showed the in-situ injection performance. At pH = 7.4, the cumulative release rate of metformin from CMCS/OHA-Met20 hydrogel was 42.7 ± 2.6 % in 6 h, and the release tended to balance after 72 h. At pH = 5.5, the release kept constant and the cumulative release rate was 79.3 ± 4.7 % at 6 h, showing good pH-responsive behavior. Metformin induced apoptosis of MCF-7 cells through the caspase 3/PARP pathway. CMCS/OHA-Met20 hydrogel could effectively kill MCF-7 cells, while reducing the cytotoxicity of free metformin to L929 cells. In vivo breast cancer recurrence experiments showed CMCS/OHA-Met20 hydrogel could achieve local injection and pH-responsive smart drug delivery at the tumor resection site, inhibiting breast cancer recurrence. Compared with direct administration, CMCS/OHA-Met20 hydrogel reduced the metformin dosage, frequency of administration and systemic side effects.

Bicomponent hydrogels assisted templating synthesis of hierarchically porous ZIF-8 for efficient antibacterial applications

A hierarchically porous ZIF-8 (HZIF-8) with pH-responsive and antibacterial activity was constructed using bicomponent hydrogel as template. The synthesized HZIF-8 was applied to load the antibacterial drug berberine hydrochloride (BBH). In vitro release studies showed that BBH@ZIF-8 and BBH@HZIF-8 displayed a sustained drug release profile, and the drug release rate increased with the decreasing pH value. The BBH@HZIFS with the highest drug loading capacity also had the highest cumulative drug release rate. At the end of 24 h, the cumulative release of BBH encapsulated in HZIFS, HZIFM and HZIFP were 92.07%, 86.60% and 88.00% at pH 5.0, respectively, higher than that of ZIF-8 (84.07%). Furthermore, in vitro antibacterial testing revealed that BBH@HZIF-8 exhibited efficient and long-lasting effects against Staphylococcus aureus, which was attributed to the synergistic bacteriostatic effect of Zn2+ and BBH released by the structural degradation of BBH@HZIF-8 under acidic conditions. In conclusion, the study provides a strategy for synthesizing HZIF-8 and demonstrates the potential of HZIF-8 as a pH-responsive nanoplatforms for antibacterial applications.

Effect and mechanism of ultraviolet-cross-linkable chitosan-carbon dots-morin hydrogel treating for rat cartilage injury

To construct a ultraviolet-cross-linkable chitosan-carbon dots-morin (NMCM) hydrogel, observe whether it can repair cartilage injury by in vivo and in vitro experiments, and explore the related mechanism. The chitosan was taken to prepare the ultraviolet (UV)-cross-linkable chitosan by combining methacrylic anhydride, and the carbon dots by combining acrylamide. The two solutions were mixed and added morin solution. After UV irradiation, the NMCM hydrogel was obtained, and its sustained release performance was tested. Chondrocytes were separated from normal and knee osteoarticular (KOA) cartilage tissue donated by patients with joint replacement and identified by toluidine blue staining. The 3rd generation KOA chondrocytes were co-cultured with the morin solutions with concentrations of 12.5, 25.0, 50.0 µmol/L and NMCM hydrogel loaded with morin of the same concentrations, respectively. The effects of morin and NMCM hydrogel on the proliferation of chondrocytes were detected by cell counting kit 8 (CCK-8). After co-cultured with NMCM hydrogel loaded with 50 µmol/L morin, the level of collagen type Ⅱ (COL-Ⅱ) of KOA chondrocytes was detected by immunofluorescence staining, and the level of reactive oxygen species (ROS) was detected by 2, 7-dichlorodihydrofluorescein diacetate (DCFH-DA) probe. Twenty 4-week old Sprague Dawley rats were selected to construct a articular cartilage injury of right hind limb model, and were randomly divided into two groups ( n=10). The cartilage injury of the experimental group was repaired with NMCM hydrogel loaded with 25 µmol/L morin, and the control group was not treated. At 4 weeks after operation, the repair of cartilage injury was observed by micro-CT and gross observation and scored by the International Cartilage Repair Association (ICRS) general scoring. The cartilage tissue and subchondral bone tissue were observed by Safranine-O-fast green staining and COL-Ⅱ immunohistochemistry staining and scored by ICRS histological scoring. The expressions of tumor necrosis factor α (TNF-α), nuclear factor κB (NK-κB), matrix metalloproteinase 13 (MMP-13), and COL-Ⅱ were detected by Western blot and real-time fluorescence quantitative PCR. NMCM hydrogels loaded with different concentrations of morin were successfully constructed. The drug release rate was fast in a short period of time, gradually slowed down after 24 hours, and the amount of drug release was close to 0 at 96 hours. At this time, the cumulative drug release rate reached 88%. Morin with a concentration ≤50 µmol/L had no toxic effect on chondrocytes, and the proliferation of chondrocytes improved under the intervention of NMCM hydrogel ( P<0.05). NMCM hydrogel loaded with morin could increase the level of COL-Ⅱ in KOA chondrocytes ( P<0.05) and reduce the level of ROS ( P<0.05), but it did not reach the normal level ( P<0.05). Animal experiments showed that in the experimental group, the articular surface was rough and the defects were visible at 4 weeks after operation, but the surrounding tissues were repaired and the joint space remained normal; in the control group, the articular surface was rougher, and no repair tissue was found for cartilage defects. Compared with the control group, the experimental group had more chondrocytes, increased COL-Ⅱ expression, and higher ICRS gross and histological scores ( P<0.05); the relative expressions of MMP-13, NF-κB, and TNF-α protein and mRNA significantly decreased ( P<0.05), and the relative expressions of COL-Ⅱ protein/COL-2a1 mRNA significantly increased ( P<0.05). NMCM hydrogel can promote chondrocytes proliferation, down regulate chondrocyte catabolism, resist oxidative stress, protect chondrocytes from cartilage injury, and promote cartilage repair.

Corn‐like mSiO2@ZIF‐8 Composite Load with Curcumin for Target Cancer Drug‐Delivery System

AbstractTo improve the drug loading rate of mesoporous silica (mSiO2), mSiO2 nanorods were synthesized by a modified sol‐gel method, then mSiO2@ZIF‐8 nanoparticles were prepared by using mSiO2 nanorods as the matrix. The structure of mSiO2 and mSiO2@ZIF‐8 were characterized. The results show that mSiO2@ZIF‐8 nanoparticles are corn‐like, with a specific surface area of 116.81 m2 g−1, pore volume of 0.31 cm3 g−1, and pore size of 8.43 nm. Curcumin (CUR) was used as an anti‐tumor model drug in drug delivery experiments. The drug loading rate of mSiO2@ZIF‐8 for CUR is 21.39 %. Before modification by Chitosan (CS) and folic acid (FA), the cumulative release rate of CUR is 30.27 % at pH 5.6 and 26.26 % at pH 7.4. After been target functionalized by CS and FA. At pH 5.6 and pH 7.4, the cumulative release rates are 34.21 % and 20.48 %, respectively, within 228 h after drug release in vitro. The results show that the drug delivery system has good pH responsiveness. Zero‐order, first‐order, Higuchi, Hixson Crowell, and Korsmeyer Peppas models were used to describe the release kinetics of mSiO2@ZIF‐8@CUR. The Higuchi model provides the highest fit for the CUR release of mSiO2@ZIF‐8@CUR.

A novel sulfated mannan-carboxymethyl-5-fluorouracil-folic acid conjugates for targeted anticancer drug delivery

CFP2 is a sulfated polysaccharide isolated from Codium fragile that shows excellent immunomodulatory activity. To reduce the side effects of 5-fluorouracil (5-FU), CFP2 was used as a macromolecular carrier to react with carboxymethyl-5-fluorouracil (C-5-FU) to form CFP2-C-5-FU, which further reacted with folic acid (FA) via an ester bond to form novel conjugates (CFP2-C-5-FU-FA). CFP2-C-5-FU-FA was confirmed by nuclear magnetic resonance (NMR) analysis. In vitro drug release results showed that the cumulative release rate of C-5-FU was 49.9% in phosphate buffer (pH 7.4) after 96 h, which was much higher than that of the other groups, indicating that CFP2-C-5-FU-FA showed controlled drug release behavior. CFP2-C-5-FU-FA also exhibited enhanced apoptosis and cellular uptake in vitro. Further, intravenous administration of CFP2-C-5-FU-FA in an HCT-116 cell-bearing xenograft mouse showed that the conjugates were safe and effective drug delivery systems. These results suggest that folate-targeted conjugates can be used effectively for efficient chemotherapy of colorectal cancer.

A new pH/redox/light stimuli-responsive magnetic molecularly imprinted polymer based on β-cyclodextrin for recognition and controlled release of andrographolide

To improve the recognition ability and the controlled release of andrographolide (ADR), it is necessary to prepare a better intelligent drug delivery carrier. In this paper, the magnetic andrographolide imprinted polymer (ADR-MMIP) with pH/redox/light triple stimulus response was successfully prepared by reverse atom transfer radical polymerization (RATRP), where ADR was as the template, β-Cyclodextrin (β-CD) and 4-amino-4′-methacrylamide azobenzene (AMAB) as the bi-functional monomers, and both of N, N′-bis (acryloyl) cystamine (BAC) and ethylene glycol dimethacrylate (EGDMA) as cross-linkers. A series of adsorption experiments indicated that ADR-MMIP had excellent adsorption and selectivity capacities with the maximum adsorption capacity 41.43 mg g−1 and the factors α 4.256 and β 1.940 for the selectivity and relative selectivity, respectively. The adsorption mechanism of ADR-MMIP was investigated the multiphase adsorption with the chemical action on heterogeneous material surface by the linear fitting with the isothermal and kinetic adsorption models, and the in-vitro ADR release showed ADR-MMIP was sensitive to the triple-stimuli of pH/redox/light with the maximum cumulative drug release rate 91.53% when the above three conditions were applied concurrently. The above information demonstrated the ADR-MMIP should be of great application potential in the ADR extraction and isolation from mixture and the intelligent drug delivery system.

The incorporated hydrogel of chitosan-oligoconjugated linoleic acid vesicles and the protective sustained release for curcumin in the gel

Assemblies of as called “chitosan hydrogel-liposome” are expected for overcoming the burst effect in drug release from chitosan (CS) hydrogels. Herein, a hydrogel delivery system made of chitosan incorporated fatty acid vesicles was constructed for protective sustained release of curcumin (Cur). The curcumin was encapsulated in the prepared oligo-conjugated linoleic acid vesicles (OCLAVs), and then the drug-embedded vesicles were constructed to Cur-OCLAVs-CS hydrogels with CS solution. The fabricated Cur-OCLAVs-CS hydrogel was fluidic at room temperature and could be rapidly gelled at 37 °C. Morphology study proves that the OCLAVs stayed as nano-vesicles in the gel. The Cur-OCLAVs-CS hydrogels effectively declined the burst effect with enhanced antioxidant activity. The Cur (400 μM)-OCLAVs-CS gel presented a cumulative release rate of 51.23 % of curcumin in 96 h, comparing to 93.37 % of that from the Cur-CS gel. Moreover, the corporation of OCLAVs and CS made the gel exhibited strong synergistic effect on the antioxidant activity, with an enhancement of up to 148.1 % on the ferric reducing power. Therefore, the hydrogel carrier made of incorporated fatty acid vesicles-chitosan can be served as an injectable or 3D printable drug delivery system, which may provide a hint to overcome the burst effect that existed in chitosan and other polysaccharide-based gels.

Peptide nanotube loaded with a STING agonist, c-di-GMP, enhance cancer immunotherapy against melanoma.

Supplementary material (synthesis and characterization of KL-7 peptide; the encapsulation rate and cumulative release rate of c-di-GMP-PNT; cytotoxicity of PNT, c-di-GMP, and c-di-GMP-PNT; anti-tumor effect of c-di-GMP-PNT (equivalent to 1 and 5 µg c-di-GMP per mouse); representative immunofluorescence images; and biosafety analysis) is available in the online version of this article at 10.1007/s12274-022-5102-z.

Repair effect of the poly (D,L-lactic acid) nanoparticle containing tauroursodeoxycholic acid-eluting stents on endothelial injury after stent implantation.

Chronic endoplasmic reticulum stress (ERS) plays a crucial role in cardiovascular diseases. Thus, it can be considered a therapeutic target for these diseases. In this study, poly (D,L-lactic acid) (PDLLA) nanoparticle-eluting stents loaded with tauroursodeoxycholic acid (TUDCA), an ER stress inhibitor, was fabricated to assess their ability to reduce endothelial cell apoptosis and promote re-endothelialization after stent implantation. PDLLA nanoparticles loaded with TUDCA were prepared via the emulsification-solvent evaporation method. The cumulative release rates of TUDCA were measured in vitro via high-performance liquid chromatography. The carotid arteries of rabbits were subsequently implanted with stents in vivo. The rabbits were then sacrificed after 4 weeks for scanning electron microscopy. Meanwhile, TUDCA concentration in the homogenate of the peripheral blood and distal vascular tissue after stent implantation was measured. The effect of TUDCA on ERS, apoptosis, and human umbilical vein endothelial cell (HUVEC) function was investigated in vitro by performing cell migration assay, wound healing assay, cell proliferation assays, endoplasmic reticulum (ER)-specific fluorescence staining, immunofluorescence, and western blotting. TUDCA nanoparticles were released slowly over 28 days. In addition, TUDCA-eluting stents enhanced re-endothelialization and accelerated the recovery of endotheliocytes in vivo. ERS and apoptosis significantly increased in H2O2-treated HUVECs in vitro. Meanwhile, TUDCA reduced apoptosis and improved function by inhibiting ERS in H2O2-treated HUVECs. Decreased rates of apoptosis and ERS were observed after silencing XBP-1s in H2O2-treated HUVECs. TUDCA can inhibit apoptosis and promote re-endothelialization after stent implantation by inhibiting IRE/XBP1s-related ERS. These results indicate the potential therapeutic application of TUDCA as a drug-coated stent.

Fabrication of soy protein isolate/κ-carrageenan hydrogels for release control of hydrophilic compounds: Flax lignans

A suitable carrier for flax lignans using Soybean protein isolated (SPI) - κ-carrageenan (KC) hydrogels was developed. The effects of KC concentration on the stability of hydrogels were investigated, as well as water holding capacity (WHC), syneresis and morphological changes. A solid-like gel network and viscoelasticity of composite hydrogels were confirmed by rheological behavior test. Scanning electron microscopy (SEM) displayed a dense and uniform structure for hydrogels with the optimum KC concentration (0.6 %). Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC) curves suggested lignan might interact with SPI and KC by hydrogen bonding or hydrophobic effects. The release of flax lignans in hydrogels was followed with Fick diffusion in simulated gastric fluids (SGF) and non-Fickian diffusion in simulated intestinal fluids (SIF), respectively. The cumulative release rate of flax lignan in complex gels (46.00 %) was lower than that of pure SPI hydrogels (77.43 %) at the end of digestion. The results indicated that KC protected the protein by hindering the accession of digestive enzymes into the hydrogels, thus resulting in a reduction of gel matrix erosion and lignan release during digestion. These findings shield a light on SPI-KC hydrogels as carriers for water-soluble bioactive compounds in food and pharmaceutical industries.

Preparation, in vitro and in vivo evaluation of pinocembrin-loaded TPGS modified liposomes with enhanced bioavailability and antihyperglycemic activity

Purpose To prepare polyethylene glycol succinate-vitamin E modified pinocembrin (PCB)-loaded liposomes (PCBT-liposomes) and evaluate PCBT-liposomal pharmacokinetics and antihyperglycemic activity. Significance The novel PCBT-liposomes demonstrated a promising application prospect as a nano drug carrier for future research. Methods Thin film dispersion was used to prepare PCBT-liposomes. We measured a series of characterization, followed by in vitro cumulative release, in vivo pharmacokinetic study, and antihyperglycemic activity evaluation. Results PCBT-liposomes displayed spherical and bilayered nanoparticles with mean particle size (roughly 92 nm), negative zeta potential (about −26.650 mV), high drug encapsulation efficiency (87.32 ± 1.34%) and good storage (at 4 or 25 °C) stability during 48 h after hydration. The cumulative release rate of PCBT-liposomes was markedly higher than free PCB in four different pH media. In vivo investigation showed that PCBT-liposomes could obviously improve oral bioavailability of PCB by 1.96 times, whereas the C max, MRT0– t , and T 1/2 of PCBT-liposomes were roughly 1.700 ± 0.139 µg·mL−1, 12.695 ± 1.647 h, and 14.244 h, respectively. In terms of biochemical analysis, aspartate amino-transferase (AST), alanine amino-transferase (ALT), interleukin-1 (IL-1), and tumor necrosis factor-α (TNF-α) concentrations in serum of diabetic mice were respectively decreased 28.28%, 17.23%, 17.77%, and 8.08% after PCBT-liposomal treatment. Conclusion These results show PCBT-liposomal preparation as an excellent nano-carrier which has the potential to improve water solubility, bioavailability, and antihyperglycemic activity of PCB, amid broadening the application of PCB in the clinical settings.

Optimization of cyclodextrin-assisted green extraction of cannabidiol from industrial hemp leaves: Release behavior, permeability, bioactivity, and stability

Cannabidiol (CBD) is an important natural compound of hemp. Cyclodextrin-assisted extraction of CBD from hemp leaves was optimized by single-factor experiments and response surface methodology. The highest extraction yield of CBD was 1.075 ± 0.012 mg/g and the recovery yield was 87.19 % using dimethyl-β-cyclodextrin (DM-βCD), which showed that the extract had a higher proportion of CBD. The optimal conditions were as follows: extraction temperature was 40 ℃, liquid-to-solid ratio was 25.17 mL/g, extraction time was 74.4 min, mass ratio of DM-βCD to hemp leaves was 1.17, and ethanol concentration was 60 %. Different characterizations demonstrated that complexation of DM-βCD promoted CBD extraction and increased the proportion of CBD in the extract. The cumulative release rate of CBD (67.98%) from the extract by DM-βCD-assisted extraction (DAHE) was much higher than that (2.62%) without DM-βCD-assisted extraction (HE). The permeability, bioactivity, and stability of DAHE were also better than that of HE. The better results of DAHE could be due to the inclusion by DM-βCD and the higher proportion of CBD. In conclusion, DM-βCD-assisted extraction was an appropriate method for CBD extraction and the obtained extract with higher CBD proportion and better bioactivity and stability could be applied in many fields.

Novel Curcumin Derivative-Decorated Ultralong-Circulating Paclitaxel Nanoparticles: A Novel Delivery System with Superior Anticancer Efficacy and Safety.

Paclitaxel (PTX) has been widely utilized for the treatment of breast cancer. However, drawbacks, such as poor aqueous solubility, rapid blood clearance and severe toxicity, greatly reduce its efficacy and safety. Herein, a novel self-developed curcumin derivative (CUD) was chosen as the carrier to develop a long-acting PTX nano-delivery system (PTX-Sln@CUD) in order to improve its pharmacokinetic behavior, anti-breast cancer efficacy and safety. PTX-Sln@CUD was prepared using solid dispersion and ultrasonic technology. Relevant physical and chemical properties, including stability and release behavior, were characterized. The clearance of PTX-Sln@CUD in vivo was studied by pharmacokinetic experiments. The anti-tumor activity of PTX-Sln@CUD was investigated in vitro and in vivo. Hemolysis experiments, acute toxicity and cumulative toxicity studies were performed in mice to determine the safety of PTX-Sln@CUD. The average particle size, PDI, Zeta potential, encapsulation efficiency and loading efficiency of the PTX-Sln@CUD were 238.5 ± 4.79 nm, 0.225 ± 0.011, -33.8 ± 1.26 mV, 94.20 ± 0.49% and 10.98 ± 0.31%, respectively. PTX-Sln@CUD was found to be stable at room temperature for half a year. The cumulative release rates of PTX-Sln@CUD at 24, 96 and 168 h were 17.98 ± 2.60, 57.09 ± 2.32 and 72.66 ± 4.16%, respectively, which were adherent to zero-order kinetics. T1/2, MRT (0-t) and AUC (0-t) of the PTX-Sln@CUD group were 4.03-fold (44.293 h), 7.78-fold (38.444 h) and 6.18-fold (14.716 mg/L*h) of the PTX group, respectively. PTX-Sln@CUD group demonstrated stronger anti-breast cancer activity than the PTX group. Importantly, the PTX-Sln@CUD group was safer compared to the PTX group both in vitro and in vivo. PTX-Sln@CUD was verified as promising therapeutic nanoparticles for breast cancer and provided a novel strategy to solve the problem of low efficacy and poor safety of clinical chemotherapy drugs.

Preparation of pelargonic acid vesicles and sustained drug release

This study has selected the medium-chain saturated fatty acid pelargonic acid as the raw material for the first time, and added the surface catalyst Tween 80 to the aqueous solution to form pelargonic acid–Tween 80 composite vesicles by a surface tension method. The compound vesicle was used to encapsulate five heterocyclic drugs (cefazolin sodium, chlorpromazine hydrochloride, gemcitabine hydrochloride, metronidazole, and isoniazid), all of which have disadvantages when used directly, and the effects of the vesicles on the five kinds of drugs were evaluated in terms of encapsulation rate and the in vitro sustained release in a simulated artificial intestinal fluid environment. The results revealed that the pelargonic acid–Tween 80 composite vesicles exhibit an encapsulation efficiency above 45%, and that the encapsulated drugs achieve a cumulative release effect of 6–10 h in a simulated artificial intestinal fluid environment, and the cumulative release rate is above 35%. This study proves that pelargonic acid–Tween 80 composite vesicles can be used as a carrier for encapsulated drugs, and this can extend the time of action of the drugs. This research illustrates the potential for application of pelargonic acid in the field of medicine.

Antimicrobial film based on poly(lactic acid) and natural halloysite nanotubes for controlled cinnamaldehyde release

Using nanocarriers to load antimicrobial agent instead of direct incorporating into film matrix could avoid burst release. Halloysite nanotubes (HNTs) are natural clays with a unique tubular structure; therefore in many studies it served as carriers to achieve a controlled release of active agents. However, when HNTs biocomposites were loaded into packaging film, the antimicrobial activity was reduced too seriously to preserve the packaged food. This study aimed to improving preservation properties of the fabricated films from two perspectives: enlarging the loading capacity of the carrier, and increasing the concentration of HNTs biocomposites. Brunauer, Emmett, Teller's test (BET) and thermogravimetric analysis (TGA) were conducted to evaluate the performance of acid treated nanocomposites. Results showed that acid treatment expanded the lumen of HNTs, increasing the loading capacity of cinnamaldehyde (Cin) from 14.6 wt% to 25.0 wt%. Active packaging films were then fabricated by incorporating Cin loaded HNTs into poly(lactic acid) matrix, and it revealed bionanocomposites at 30 wt% achieved the optimum film, considering the mechanical performance and controlled release of Cin. Cumulative release rate of the films were further verified by the fumigant antimicrobial activity. This study demonstrates a solution for improving the antimicrobial properties of packaging film without comprising mechanical strength.

Rotenone encapsulated in pH-responsive alginate-based microspheres reduces toxicity to zebrafish

Rotenone is a botanical pesticide and has long been used for control of insect pests and also as a natural piscicide for management of fish populations in many countries. Field application for pest control, however, often encounters the movement of rotenone into surface water due to spray drift or surface runoff after rainfall, which could potentially result in water pollution and unexpected death of fishes. To minimize its effect on freshwater and the problem of fish dying, one solution was to encapsulate rotenone in specific microspheres, limiting its release and reducing its toxicity since rotenone can be quickly degraded under sunlight. In this study, pH-responsive alginate-based microspheres were synthesized to encapsulating rotenone, which were designated as rotenone beads. The rotenone beads, along with alginate beads (devoid of rotenone) were characterized and evaluated for their responses to pH and effects on zebrafish. Results showed that the microspheres had high loading efficiency (4.41%, w/w) for rotenone, and rotenone beads well responded to solution pH levels. The cumulative release rates of rotenone from the beads were 27.91%, 42.72%, and 90.24% at pH 5.5, 7.0, and 9.0, respectively. Under acidic conditions, the rotenone release rate was lower due to hydrogen bonding. On the contrary, rotenone became more quickly released at the high pH due to intermolecular repulsion. The toxicity of rotenone beads to zebrafish and fish embryos at a pH of 5.5 was reduced by 2- and 4-fold than chemical rotenone. Since pH levels in most freshwater lakes, ponds, and streams vary from 6 to 8, rotenone release from the beads in such freshwater could be limited. Thus, the synthesized rotenone beads could be relatively safely used for pest control with limited effects on freshwater fishers.

Bifunctional core-shell structure NaA zeolite@mesoporous-silica/curcumin nanocomplexes for removing heavy metals and reduction of Cadmium-induced damage

Heavy metals had been reported to bioaccumulate in many organs and adversely affect the functions of these organs. Therefore, it was of great significance to develop bifunctional drug carrier, which could remove heavy metals and load curcumin with multiple protective properties. Newly designed drug carrier combining a core of NaA zeolite and a mesoporous silica (MS) shell has been developed, which the core is used to remove heavy metals, the outer shell loads drugs, and explore the dual functions. In this work, Curcumin-loaded on an amino modified NaA@MS-0.2 (NaA@MS-0.2-N-Cur) are 220 nm sized and have a mesoporous silica shell of 30 nm thickness. The cumulative drug release from NaA@MS-0.2-N-Cur were 14.1 and 43.0% in pH 7.4 and pH 1.2 PBS. NaA@MS-0.2-N-Cur released in 100 mL of pH 1.2 PBS containing 100 mg/L Cd2+, the cumulative drug release rate was 43.9%, the sorption rate of Cd2+ was 79.7%, and the sorption capacity of Cd2+ was 109.5 mg/g. Taken together, these results suggested that core-shell structure nanocomplexes are bifunctional and its cumulative drug release rate increased in pH 1.2 PBS. And this drug carrier has great potential for protecting the body from damage for heavy metal.

An antibacterial coaxial electrospun polylactic acid/silk fibroin loaded with nano-ZnO and Voltaren

• The bifunctional PLA/SF core-shell fibers had been designed and prepared. • Voltaren was encapsulated into the core of fibers to relieve burst release effectively. • The core-shell fibers with nano-ZnO loaded into the shell exhibited obvious antibacterial activity. • SEM images revealed the core-shell fibers with a mean diameter of ∼700 nm. The coaxial electrospinning was used to prepare Voltaren-loaded and nano-ZnO-loaded core-shell polylactic acid (PLA)/silk fibroin (SF) fibers. The elemental morphology, compositions, the release behavior and the antibacterial property of the fibers were investigated. The result showed that the fibers had a clear core-shell structure and nano-ZnO was observed in the shell. The cumulative drug release rates of core-shell fibers were 48.8% and 72.6% at 100 min and 600 min, respectively. The core-shell PLA/SF had a smaller initial release of Voltaren and an obvious antibacterial activity against Escherichia coli and Staphylococcus aureus under an absence of light.

Experimental study on combustion and emission characteristics of diesel engine with high supercharged condition

The effect of diesel engine continuous strengthening on combustion and emission remains to be clarified. This study tested combustion and emission processes at different intake pressures on a single-cylinder diesel engine. The results show that the combustion of diesel engine after continuous strengthening is concentrated in diffusion and post-combustion periods, the overall heat release slows down, and the power increment decreases gradually. When the intake pressure increases to 0.25MPa, the premixed heat release peak almost disappears, while the value of diffusion combustion period increases significantly. Meanwhile, the gravity center of combustion moves backward and the cumulative heat release rate decreases. The power increases by 95% as the intake pressure increases from 0.15MPa to 0.25MPa, but only 44% as it further increases to 0.36MPa. Meanwhile, the exhaust temperature increases after high supercharging. The above effects are more prominent at high excess air coefficient and low speed. Moreover, with the decrease of excess air coefficient, the proportion of heat release in the post-combustion stage to the whole combustion increases and the power increment is limited. However, the thermal efficiency decreases approximately linearly and the fuel consumption rate increases sharply. In addition, as the excess air coefficient decreases, the exhaust temperature increases, PM increases and NOx decreases. The above effects are more pronounced at higher boost ratio.