Selenizing chitooligosaccharide with site-selective modification to alleviate acute liver injury in vivo.

Two selenized chitooligosaccharide (O-Se-COS and N,O-Se-COS) with different sites modification were synthesized to alleviate liver injury in vivo. Comparing to traditional COS, both selenized COS exhibited enhanced reducibility as well as antioxidant capacity in vitro. Furthermore, O-Se-COS demonstrated superior efficacy in reducing intracellular reactive oxygen species (ROS) and mitochondrial damage compared to N,O-Se-COS as its enhanced cellular uptake by the positive/negative charge interactions. Two mechanisms were proposed to explained these results: one is to enhance the enzymatic activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), which effectively scavenge free radicals; the other is to down-regulate intracellular cytochrome P450 (CYP2E1) levels, inhibiting carbon tetrachloride (CCl4)-induced peroxidation damage. In vivo studies further demonstrated the effective alleviation of CCl4-induced liver injury by selenized COS, with therapeutic efficacy observed in the following order: O-Se-COS > N,O-Se-COS > COS. Finally, hemolysis and histological tests confirmed the biosafety of both selenized COS. Taken together, these finding demonstrated that selenium has the potential to improve the biological activity of COS, and precise selenylation was more conducive to achieving the synergistic effect where 1 + 1>2.

Self-assembly of maltose-albumin nanoparticles for efficient targeting delivery and therapy in liver cancer.

The effective delivery and targeted release of drugs within tumor cells are critical factors in determining the therapeutic efficacy of nanomedicine. To achieve this objective, a conjugate of maltose (Mal) and bovine serum albumin (BSA) was synthesized by the Maillard reaction and self-assembled into nanoparticles with active-targeting capabilities upon pH/heating induction. This nanoparticle could be effectively loaded with doxorubicin (DOX) to form stable nanodrugs (Mal-BSA/DOX) that were sensitive to low pH or high glutathione (GSH), thereby achieving a rapid drug release (96.82 % within 24 h). In vitro cell experiments indicated that maltose-modified BSA particles efficiently enhance cellular internalization via glucose transporters (GLUT)-mediated endocytosis, resulting in increased intracellular DOX levels and heightened expression of γ-H2AX. Consequently, these results ultimately lead to selective tumor cells death, as evidenced by an IC50 value of 3.83 µg/mL in HepG2 cells compared to 5.87 µg/mL in 293t cells. The efficacy of Mal-BSA/DOX in tumor targeting therapy has been further confirmed by in vivo studies, as it effectively delivered a higher concentration of DOX to tumor tissue. This targeted delivery approach not only reduces the systemic toxicity of DOX but also effectively inhibits tumor growth (TGI, 75.95 %). These findings contribute valuable insights into the advancement of targeting-albumin nanomedicine and further support its potential in tumor treatment.

A sequentially responsive cascade nanoplatform for increasing chemo-chemodynamic therapy.

Poly(lactide-co-glycolide) (PLGA) is promising carrier material for drugs delivery in cancer therapy. However, the slow degradation and lack of targeting have greatly limited the clinical effectiveness of PLGA-based nanomedicines. Herein, we fabricated a hybrid nanosystem (3 P @ He/Pt-NPs) comprising of acid-sensitive polymer (mPOE-PLGA), active-targeting polymer (PBA-PLGA) and therapeutic agents (hemin+cisplatin) to combat these problems. In neutral environment, PEGylation can effectively improve the blood stability and circulation time of hybrid nanosystem. After reaching tumor regions, this nanosystem efficiently increased cellular uptake by dePEGylation and PBA-mediated active-targeting. Furthermore, encapsulated hemin could catalyze the oxygen bubbles generation, which remarkably increasing the drugs release rate. Subsequently, hybrid particles produced a higher cell-killing effect to lung cancer cells (A549) by the combination therapy (chemotherapy and chemodynamic therapy (CDT)). Importantly, cisplatin further amplified CDT effect by inducing H2O2 regeneration owing to the cascade enzymatic reactions, while hemin decreased intracellular glutathione (GSH) level, resulting in a low detoxification effect to cisplatin. Thus, hybrid particles could efficiently inhibit drug-resistant tumor growth and the inhibition rate reached 83.2%. Overall, this hybrid polymer nanosystem improve the drawbacks of PLGA-based nanocarriers, and can realize a cascading enhanced tumor treatment.

Dual-pH responsive chitosan nanoparticles for improving in vivo drugs delivery and chemoresistance in breast cancer.

Efficient intracellular drugs delivery and accumulation are the key determinant for overcoming tumor multidrug resistance (MDR). To realize this purpose, dual-pH responsive chitosan nanoparticles (DCCA/DOX-NPs) were fabricated to treat MDR tumor in human breast cancer (MCF-7/ADR). The particles were firstly sensitive to tumor extracellular pH 6.5, contributing to the surface charge reversal (-6.32 â†’ 11.45 mV) by the cleavage of ß-carboxylic amide, which greatly increased cellular uptake efficiency. DCCA/DOX-NPs further responded to lower intracellular pH 5.0, thereby triggering DOX and cinnamaldehyde (CA) release by the cleavage of Schiff base. Cells assays verified that dual-pH sensitive particles caused higher toxicity in MDR tumor cells. Furthermore, the particles could overcome tumor resistance by decreasing intracellular levels of ATP and PARP-1, eventually receiving stronger antitumor efficiency in vivo (84.94%). Overall, this amphiphilic chitosan nanosystem with various bioactivities could work as an alternative promising for treating MDR tumor.

Acid-sensitive and L61-crosslinked hyaluronic acid nanogels for overcoming tumor drug-resistance.

Low intracellular drugs concentration is one of the main representations of multidrug resistance (MDR), which often results in a weak or failed chemotherapy on cancer treatment. Herein, an acid-sensitive and pluronic L61-linked hyaluronic acid nanogels (HA-L61OE/NGs) were developed for solving this problem. The nanogels could well hold more drugs under neutral condition, while triggering efficiently drugs release (61.42% within 24 h) in acidic environment. In vitro cells experiments demonstrated that the nanogels greatly increased intracellular drugs concentration by CD44-mediated endocytosis and L61-mediated anti-MDR effect, resulting in the enhanced cell-killing in MDR cells. In vivo studies verified HA-L61OE/NGs could avoid drugs leakage in blood and reduce systemic toxicity. Subsequently, the specific accumulation and penetration of nanogels at tumor regions lead to the highest tumor growth inhibition (TGI, 77.42%). Overall, HA-L61OE/NGs were effective on MDR tumor therapy and expected to be further used in clinical trials.

Glucose-Targeted Hydroxyapatite/Indocyanine Green Hybrid Nanoparticles for Collaborative Tumor Therapy.

Nanoscale hydroxyapatite (nHA) is considered as a promising drug carrier or therapeutic agent against malignant tumors. But the strong agglomeration tendency and lack of active groups seriously hamper their usage in vivo. To address these issues, we fabricated an organic-inorganic hybrid nanosystem composed of poly(acrylic acid) (PAA), nHA, and indocyanine green (ICG), and further modified with glucose to give a targeting nanosystem (GA@HAP/ICG-NPs). These hybrid nanoparticles (∼90 nm) showed excellent storage and physiological stability assisted by PAA and had a sustained drug release in an acidic tumor environment. In vitro cell experiments confirmed that glucose-attached particles significantly promoted cellular uptake and increased intracellular ICG and Ca2+ concentrations by glucose transporter 1 (GLUT1)-mediated endocytosis. Subsequently, the excessive Ca2+ induced cell or organelle damage and ICG triggered photothermal and photodynamic effects (PTT/PDT) under laser irradiation, resulting in enhanced cell toxicity and apoptosis. In vivo tests revealed that the hybrid nanosystem possessed good hemocompatibility and biosafety, facilitating in vivo circulation and usage. NIR imaging further showed that tumor tissues had more drug accumulation, resulting in the highest tumor growth inhibition (87.89%). Overall, the glucose-targeted hybrid nanosystem was an effective platform for collaborative therapy and expected to be further used in clinical trials.

Aggregation Behavior of Acylated Pepsin-Solubilized Collagen Based on Fluorescence Spectrum Technology.

The aggregation behavior of collagen-based materials plays an important role in their processing because it could affect their physicochemical properties. Based on the intrinsic fluorescence characteristic of tyrosine, fluorescence spectrum technology was used to investigate the aggregation state of the acylated collagen molecules in aqueous solution. The results showed that the aggregate degree of the acylated collagen was higher than that of the native collagen due to the hydrophobic interaction. With the increase of concentrations of the acylated collagen or at NaCl higher than 40 mmol/L, the aggregate degree of the acylated collagen molecules increased. When the pH was close to the isoelectric point of the acylated collagen, the hydrophobic interaction and the hydrogen bond helped to increase the aggregation degree. However, with the increase of temperature (10-70 ℃), the aggregation state of the acylated collagen decreased gradually due to the quenching, the molecular collision, and the broken of hydrogen bonds. Furthermore, two-dimensional correlation spectroscopy (2D-COS) showed that the response order was 360 > 305 nm at various acylated collagen and NaCl (>40 mmol/L) concentrations, while the response order was 305 > 360 nm when the pH value was increased from 5.0 to 9.0. Temperature-dependent 2D-COS showed there were four bands that occurred and the response order was listed as follows: 293 > 305 > 360 > 420 nm. In brief, the results might provide an important guide for molding processes of the acylated collagen.

Description of two new species in long-horned crane fly subgenus Tipula (Sivatipula) (Diptera: Tipulidae) from China.

Two new species of subgenus Tipula (Sivatipula) Alexander, 1964, T. (S.) multidentata sp. nov. (southern China: Guizhou) and T. (S.) tergatruncata sp. nov. (southern China: Chongqing) are described and illustrated.

New Insights into SN-38 Glucuronidation: Evidence for the Important Role of UDP Glucuronosyltransferase 1A9.

Glucuronidation of SN-38 serves as an important metabolic pathway in determining the toxic effects of irinotecan. The role of UDP-glucuronosyltransferases (UGT) 1A9 in SN-38 glucuronidation pathway is very confusing. This study re-investigates the pathway through testing effects of bovine serum albumin (BSA) and the selective inhibitor on SN-38 glucuronidation in pooled human liver microsomes (HLM) and recombinant UGT1A1/UGT1A9. For UGT1A1, SN-38 glucuronidation was little affected by BSA. Whether in the presence of BSA or not, the reactions both obey Michaelis-Menten kinetics with closed Vmax/Km values. For UGT1A9 and HLM, BSA can significantly accelerate SN-38 glucuronidation activities and similar effects are further observed on kinetic patterns. In the absence of BSA, reactions by HLM and UGT1A9 both display substrate inhibition kinetics. When BSA is included in the incubations, the reactions exhibit Michaelis-Menten kinetics. To get the true contribution of UGT1A9 in SN-38 glucuronidation, a relative activity factor (RAF) approach was additionally used. It is suggested that UGT1A9 and 1A1 contribute equally to SN-38 glucuronidation in HLM. Furthermore, in the presence of BSA, magnolol, a selective UGT1A9 inhibitor, displays moderate inhibition against HLM. Results together conclude that UGT1A9 serves as an additional important contributor to hepatic SN-38 glucuronidation.

[Aggregation Behavior of Collagen-Based Surfactant Molecules in Aqueous Solutions Based on Synchronization Fluorescence Spectrum Technology].

Due to the intrinsic fluorescence characteristic of tyrosine (Tyr) and phenylalanine (Phe), synchronization fluorescence spectrum technology which adopted the constant wavelength difference (Δλ = 15 nm) was selected to investigate the effects of collagen-based surfactant (CBS) concentration, pH, NaCt concentration and temperature on the aggregation state of CBS molecules in aqueous solutions. Meanwhile, temperature-dependent two-dimensional (2D) synchronization fluorescence correlation analyses was used to investigate the variation order of Tyr and Phe residues in CBS molecules with the change of temperature. The results showed that the characteristic absorption peaks located at 261 and 282 nm were attributed to Phe and Tyr, respectively. With the increase of CBS concentration, the amount of Phe and Tyr residues increased gradually which resulted in the increase of aggregate degree of CBS molecules and then led to the increase of fluorescence intensity. When the pH value (pH 5.0) of CBS solutions was close to the isoelectric point of CBS, the aggregate degree of CBS molecules increased due to the increase of the hydrophobic interaction and the formation ability of hydrogen bond. Additionally, with the increase of NaCl concentration, the repulsion force for inter/intra-molecules of CBS decreased, which helped to improve the aggregation behavior of CBS molecules. However, with the increase of temperature, the aggregation state of CBS was changed to be monomolecular state, and then resulted in the decrease of the fluorescence intensity gradually due to the quenching, the denaturation and the decrease of hydrogen bond formation ability. Furthermore, temperature-dependent 2D synchronization fluorescence correlation spectroscopy demonstrated that at lower temperature (10-40 degrees C), the aggregate state of CBS changed to be loose state and then Phe residues located in the inside of the aggregate varied before Tyr residues; while in the heating process of 45-70 degrees C, the monomolecular state of CBS changed to be random coil conformation, the separation distance between Tyr residues increased and the hydrogen bond formation ability reduced strongly, which led to Tyr residues changed before Phe residues.

Structural properties of pepsin-solubilized collagen acylated by lauroyl chloride along with succinic anhydride.

The structural properties of pepsin-solubilized calf skin collagen acylated by lauroyl chloride along with succinic anhydride were investigated in this paper. Compared with native collagen, acylated collagen retained the unique triple helix conformation, as determined by amino acid analysis, circular dichroism and X-ray diffraction. Meanwhile, the thermostability of acylated collagen using thermogravimetric measurements was enhanced as the residual weight increased by 5%. With the temperature increased from 25 to 115 °C, the secondary structure of native and acylated collagens using Fourier transform infrared spectroscopy measurements was destroyed since the intensity of the major amide bands decreased and the positions of the major amide bands shifted to lower wavenumber, respectively. Meanwhile, two-dimensional correlation spectroscopy revealed that the most sensitive bands for acylated and native collagens were amide I and II bands, respectively. Additionally, the corresponding order of the groups between native and acylated collagens was different and the correlation degree for acylated collagen was weaker than that of native collagen, suggesting that temperature played a small influence on the conformation of acylated collagen, which might be concluded that the hydrophobic interaction improved the thermostability of collagen.

Properties of collagen gels cross-linked by N-hydroxysuccinimide activated adipic acid deriviate.

In order to improve the properties of collagen gel, N-hydroxysuccinimide activated adipic acid derivative (NHS-AA) was introduced into the formation of collagen fibrils. NHS-AA with different [NHS-AA]/[NH2] ratios (0.1-1.5, calculated by [ester group] of NHS-AA and [NH2] of lysine and hydroxylysine residues of collagen) was added after, simultaneously with or before the formation of collagen fibrils (abbreviated CAF, CSF and CBF, respectively) to obtain different collagen gels. With the same dose of NHS-AA, the cross-linking degree for CAF was lower than those for CSF and CBF. The formation of collagen fibrils was restrained by NHS-AA for CSF and CBF while that for CAF was unaffected. When the dose of NHS-AA increased from 0.1 to 1.5, the water contents of CSF and CBF increased while that of CAF had no obvious change. With lower dose of NHS-AA (0.1), CAF possessed higher value of G' (87.3Pa) and the best thermal stability (47.6°C). As the ratio of [NHS-AA]/[NH2] increased to 1.5, CSF had the maximum value of G' (288.8Pa) and CAF had the best thermal stability (52.9°C). These results showed collagen gels with different properties could be prepared by adding NHS-AA with different adding sequence and dose.

Physicochemical properties of collagen solutions cross-linked by glutaraldehyde.

The physicochemical properties of collagen solutions (5 mg/ml) cross-linked by various amounts of glutaraldehyde (GTA) [GTA/collagen (w/w) = 0-0.5] under acidic condition (pH 4.00) were examined. Based on the results of the determination of residual amino group content, sodium dodecyl sulphate-polyacrylamide gel electrophoresis, dynamic rheological measurements, differential scanning calorimetry and atomic force microscopy (AFM), it was proved that the collagen solutions possessed strikingly different physicochemical properties depending on the amount of GTA. At low GTA amounts [GTA/collagen (w/w) ≤ 0.1], the residual amino group contents of the cross-linked collagens decreased largely from 100% to 32.76%, accompanied by an increase in the molecular weight. Additionally, increases of the fiber diameter and the values of G', G″ and η* were measured, while the thermal denaturation temperature (Td) did not change visibly and the fluidity of collagen samples was still retained with increasing the GTA amount. When the ratio of GTA to collagen exceeded 0.1, although the residual amino group content only decreased by ~8.2%, the cross-linked collagen solution [GTA/collagen (w/w) = 0.3] displayed a clear loss of flow and a sudden rise (~2.0 °C) of the Td value compared to the uncross-linked collagen solution, probably illustrating that the collagen solution was converted into a gel with mature network structure-containing nuclei observed in AFM image. It was conjectured that the physicochemical properties of the collagen solutions might be in connection with the cross-linking between collagen molecules from the same aggregate or different aggregates.

Characterization of acylated pepsin-solubilized collagen with better surface activity.

A new kind of acylated collagen with water solubility and better surface activity was prepared via reaction of pepsin-solubilized calf skin collagen with lauroyl chloride and succinic anhydride in this paper. The equilibrium surface tension and the isoelectric point were 55.92 mN/m and 4.93 respectively, suggesting that acylated collagen had surface activity as well as water solubility. Meanwhile, the results of Fourier transform infrared spectroscopy analyses and electrophoresis patterns demonstrated that the triple helix conformation of collagen was not destroyed, but the subunits of acylated collagen shifted to higher molecular weight than those of native collagen. Scanning electron microscope and differential scanning calorimeter measurements revealed that lyophilized acylated collagen exhibited relatively well-distributed pore structure and its denaturation temperature was about 9.0 °C higher than that of native collagen. Additionally, the increase of the diameter of the fibrils was observed by atomic force microscopy. Acylated collagen with water solubility and better surface activity might broaden the application of collagen-based materials to cosmetics, drug delivery and pharmacotherapy.

The influence of chondroitin 4-sulfate on the reconstitution of collagen fibrils in vitro.

Collagen fibrils were in vitro reconstituted from the aggregated collagen solution in the presence of a wide range of collagen/chondroitin 4-sulfate (Col/C4S) ratios. As revealed by turbidimetric measurement, the collagen fibril formation is significantly accelerated by C4S. The turbidity values of both the solution after 30 min preincubation at 4°C and the gels after 60 min preincubation at 37°C become larger with the increase of C4S amount. According to the results obtained from turbidimetric measurement and atomic force microscopy observation of solutions, it is predicted that the preincubation of Col/C4S blends at 4°C is necessary to initiate the Col/C4S binding and then promote the further lateral fusion of collagen aggregates in solution. The interactions between collagen and C4S are also vital in the growth phase of collagen self-assembly. Collagen quantitation data show that the amounts of collagen incorporated into self-assembled cofibrils increase a lot as a result of the presence of C4S. Differential scanning calorimetry measurement shows that the thermal stability of cofibrils keeps increasing with the ascending amount of incorporated C4S. It is suggested that the bound C4S might be captured inside the cofibrils acting as promoter and stabilizer. Atomic force microscopy and scanning electron microscopy observations of self-assembled fibrils indicate that the size increase of the self-assembled cofibrils depends on the lateral accretion of small collagen fibrils, while the self-assembly mode of collagen is not affected.

[Screening and identification of a new Bacillus strain producing keratinase].

OBJECTIVE: New wild strains, which were endowed with an effective depilation as their abilities to produce keratinase, were isolated to develop the bio-deliplatory agent in the sulfur-free tanning. METHODS: A polyphase screening method was used to obtain the high-yielding wild strains. In this method, the sewage sample was obtained from the specific circumstance where the raw hides were stored,and then enriched by adding the defatted wool power as an inducer in the medium. Furthermore,the strains were screened via assessing the ability of the depilation of their fermentation broth. Finally, the isolated strain was identified according to their morphological features, physiological and biochemical characteristics, automatic identification by Biolog system as well as phylogenetic analysis of 16SrDNA sequences. RESULTS: A higher activity and remarkable dehairing capability with sulfur-free was obtained. The results of identification indicated that the strain X-47 was the most closely related to Bacillus licheniformis, so it was named Bacillus licheniformis X-47. CONCLUSION: The wild strain Bacillus licheniformis X-47 was isolated successfully by the method of polyphase screening. It had a high keratinase-producing activity, high efficient of depilation and weak effect on collagen, which suggested that it has a considerable potential of developing the sulfur-free bio-depilation product.