Fluorine-thiol displacement probes for acetaminophen's hepatotoxicity

Chemicals possessing reactive electrophiles can denature innate proteins leading to undesired toxicity, and the overdose-induced liver injury by drugs containing electrophiles has been one of the major causes of non-approval and withdraw by the US Food and Drug Administration (FDA). Elucidating the associated proteins could guide the future development of therapeutics to circumvent these drugs' toxicities, but was largely limited by the current probing tools due to the steric hindrance of chemical tags including the common "click chemistry" labels. Taking the widely used non-steroidal anti-inflammatory drug acetaminophen (APAP) as an example, we hereby designed and synthesized an APAP analogue using fluorine as a steric-free label. Cell toxicity studies indicated our analogue has similar activity to the parent drug. This analogue was applied to the mouse hepatocellular proteome together with the corresponding desthiobiotin-SH probe for subsequent fluorine-thiol displacement reactions (FTDRs). This set of probes has enabled the labeling and pull-down of hepatocellular target proteins of the APAP metabolite as validated by Western blotting. Our preliminary validation results supported the interaction of APAP with the thioredoxin protein, which is an important redox protein for normal liver function. These results demonstrated that our probes confer minimal steric perturbation and mimic the compounds of interest, allowing for global profiling of interacting proteins. The fluorine-thiol displacement probing system could emerge as a powerful tool to enable the investigation of drug-protein interactions in complex biological environments.

Click chemistry extracellular vesicle/peptide/chemokine nanocarriers for treating central nervous system injuries

Central nervous system (CNS) injuries, including stroke, traumatic brain injury, and spinal cord injury, are essential causes of death and long-term disability and are difficult to cure, mainly due to the limited neuron regeneration and the glial scar formation. Herein, we apply extracellular vesicles (EVs) secreted by M2 microglia to improve the differentiation of neural stem cells (NSCs) at the injured site, and simultaneously modify them with the injured vascular targeting peptide (DA7R) and the stem cell recruiting factor (SDF-1) on their surface via copper-free click chemistry to recruit NSCs, inducing their neuronal differentiation, and serving as the nanocarriers at the injured site (Dual-EV). Results prove that the Dual-EV could target human umbilical vascular endothelial cells (HUVECs), recruit NSCs, and promote the neuronal differentiation of NSCs in vitro. Furthermore, 10 miRNAs are found to be upregulated in Dual-M2-EVs compared to Dual-M0-EVs via bioinformatic analysis, and further NSC differentiation experiment by flow cytometry reveals that among these miRNAs, miR30b-3p, miR-222-3p, miR-129-5p, and miR-155-5p may exert effect of inducing NSC to differentiate into neurons. In vivo experiments show that Dual-EV nanocarriers achieve improved accumulation in the ischemic area of stroke model mice, potentiate NSCs recruitment, and increase neurogenesis. This work provides new insights for the treatment of neuronal regeneration after CNS injuries as well as endogenous stem cells, and the click chemistry EV/peptide/chemokine and related nanocarriers for improving human health.

Preparation of silk fibroin/hyaluronic acid composite hydrogel based on thiol-ene click chemistry / 浙江大学学报·医学版

OBJECTIVES@#To design and prepare silk fibroin/hyaluronic acid composite hydrogel.@*METHODS@#The thiol modified silk fibroin and the double-bond modified hyaluronic acid were rapidly cured into gels through thiol-ene click polymerization under ultraviolet light condition. The grafting rate of modified silk fibroin and hyaluronic acid was characterized by 1H NMR spectroscopy; the gel point and the internal microstructure of hydrogels were characterized by rheological test and scanning electron microscopy; the mechanical properties were characterized by compression test; the swelling rate and degradation rate were determined by mass method. The hydrogel was co-cultured with the cells, the cytotoxicity was measured by the lactate dehydrogenase method, the cell adhesion was measured by the float count method, and the cell growth and differentiation on the surface of the gel were observed by scanning electron microscope and fluorescence microscope.@*RESULTS@#The functional group substitution degrees of modified silk fibroin and hyaluronic acid were 17.99% and 48.03%, respectively. The prepared silk fibroin/hyaluronic acid composite hydrogel had a gel point of 40-60 s and had a porous structure inside the gel. The compressive strength was as high as 450 kPa and it would not break after ten cycles. The water absorption capacity of the composite hydrogel was 4-10 times of its own weight. Degradation experiments showed that the hydrogel was biodegradable, and the degradation rate reached 28%-42% after 35 d. The cell biology experiments showed that the cytotoxicity of the composite gel was low, the cell adhesion was good, and the growth and differentiation of the cells on the surface of the gel were good.@*CONCLUSIONS@#The photocurable silk fibroin/hyaluronic acid composite hydrogel can form a gel quickly, and has excellent mechanical properties, adjustable swelling rate and degradation degree, good biocompatibility, so it has promising application prospects in biomedicine.

Pretargeted immunoPET imaging with epidermal growth factor receptor monoclonal antibody in mouse models / 中华核医学与分子影像杂志

Objective:To explore the feasibility of pretargeting technique for immunoPET with epidermal growth factor receptor (EGFR) monoclonal antibody in EGFR positive/negative tumor bearing mice.Methods:Cetuximab- Trans-cyclooctene (TCO)was obtained by modifying Cetuximab with TCO- N-hydroxysuccinimide (NHS). 2, 2′-((6-amino-1-(4, 7-bis-(carboxymethyl)-1, 4, 7-triazonan-1-yl)hexan-2-yl)azanediyl)-diacetic acid (L-NETA)was used as a chelating agent to prepare the radioligand 68Ga-L-NETA-tetrazine (Tz), then the labeling rate and in vitro stability of the product were determined. Human basal breast cancer cells MDA-MB-468 (EGFR+ ) and MDA-MB-231 (EGFR-) were cultured in vitro. In vitro experiments were performed to explore the specificity of the probe and the feasibility of pretargeting technique. Nude mice (Balb/c-nu) bearing xenografts of the above two cell lines were established. Cetuximab-TCO (50 μg) was injected into the tumor-bearing mice in advance, then 68Ga-L-NETA-Tz was injected at different time points (48, 36, 24 and 12 h), and pretargeting was realized through " click chemistry" . Small-animal PET imaging and biodistribution were performed to evaluate pharmacokinetic properties and specificity of the probe. The one-way analysis of variance was used to compare the data. Results:The 68Ga-L-NETA-Tz molecular probe was successfully prepared with the labeling yield >95%, and the radiochemical purity was >95% after 2 h. Cetuximab-TCO and 68Ga-L-NETA-Tz were added to MDA-MB-468 cells successively, and the cell uptake rate reached (0.69±0.04)% at 1 h, which demonstrated the feasibility of the pretargeting technique. PET imaging and biodistribution results showed that the best imaging results were obtained in 36 h pre-injection group, in which the tumor uptake was the highest ((0.77±0.05) percentage activity of injection dose per gram of tissue (%ID/g), 1 h) and the tumor/muscle ratio was optimal (4.67±0.46); the tumor uptake in the blocking group, the group without injecting Cetuximab-TCO, and the MDA-MB-231 group were significantly lower ((0.35±0.01), (0.39±0.05), (0.45±0.10) %ID/g; F=15.50, P=0.002). Conclusions:EGFR targeted immunoPET imaging is successfully performed in mouse models of breast cancer by injecting Cetuximab-TCO and 68Ga-L-NETA-Tz successively. It provides an effective method for immunoPET imaging of monoclonal antibodies.

Preparation of 68Ga labeled pre-targeted molecular probe based on bio-orthogonal Diels-Alder click chemistry and CD11b receptor targeted imaging in CT26 colon cancer mouse models / 中华核医学与分子影像杂志

Objective:To prepare a 68Ga labeled probe targeting integrin alpha M(CD11b) receptor, namely 68Ga-1, 4, 7-triazacyclononane-1, 4, 7-triacetic acid-Glycine-Arginine-Glutamate-Arginine-Glutamate-polyethylene glycol 11-1, 2, 4, 5-terazine/CD11b antibody-F(ab′) 2-trans-cyclooctene ( 68Ga-NOTA-Polypeptide-PEG 11-Tz/anti-CD11b-F(ab′) 2-TCO), and to explore its feasibility as a molecular probe for CD11b receptor through microPET imaging. Methods:Immunofluorescence was used to detect the expression of CD11b on the surface of RAW264.7 cell. CD11b specific monoclonal antibody (M1/70) was conjugated with TCO, and anti-CD11b-F(ab′) 2-TCO fragment was obtained. The ligand NOTA-Polypeptide-PEG 11-Tz was labeled with 68Ga, and its specific activity and radiochemical purity were detected. Pre-targeted cell binding experiment was conducted to evaluate the binding ability of molecular probe. CT26 colon cancer bearing mouse models were established, and then pre-targeted biodistribution and imaging experiments were performed. Immunohistochemical experiment was used to verify the expression of CD11b receptor in tumor. The one-way analysis of variance was used to compare the data. Results:The results of immunofluorescence demonstrated CD11b receptor was highly expressed on the surface of RAW264.7 cell. Anti-CD11b-F(ab′) 2-TCO fragment was verified by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). 68Ga-NOTA-Polypeptide-PEG 11-Tz was successfully synthesized, with the labeling efficiency of 94.6%. The specific activity was 7.0-7.4 MBq/μg, and the radiochemical purity was higher than 95%. Pre-targeted cell binding experiment confirmed that the molecular probe bound to the CD11b receptor. The biodistribution and imaging experiments showed that the kidney radioactivity uptake was high at pre-targeted 4, 12 and 24 h intervals, which proved that probe was excreted through the urinary system. In addition, molecular probe had higher radioactive uptake at the tumor site, with the tumor/muscle ratios of 9.23±1.45, 12.53±1.36 and 10.74±1.11 ( F=848.8, P<0.05). When the radioligand was injected 1 h after the pre-positioned 12 h interval, the images contrast was the best, with the standardized uptake value (SUV) in tumor and muscle of 0.67±0.12, 0.09±0.04, respectively. Immunohistochemistry verified the highly expression of CD11b receptor in tumor. Conclusions:The pre-targeted molecular probe 68Ga-NOTA-Polypeptide-PEG 11-Tz/anti-CD11b-F(ab′) 2-TCO is successfully synthesized. The molecular probe has targeting ability for CD11b + colon cancer, and is expected to be used as a tracer targeting CD11b receptor in vivo.

Applicatoin progress on click chemistry in targets identification of bioactive components from Chinese materia medica / 中草药

The target is the basis for the active ingredients of Chinese materia medica (CMM), which plays an important role in the patients’ body. Target identification is the key work for the development of CMM. However, the current studies on the target of CMM are still limited, and it has become a bottleneck in the modernization of CMM. Therefore, new ideas and new technologies are required for the research on targets. Recently, a new method for the study of targets has been provided by the technology of activity-based protein profiling represented by click chemistry. The application of click chemistry in target identification of CMM in recent years is briefly reviewed and summarized, and the trends of application and development of click chemistry are prospected in this review.

Click Chemistry-Based Injectable Hydrogels and Bioprinting Inks for Tissue Engineering Applications

BACKGROUND: The tissue engineering and regenerative medicine approach require biomaterials which are biocompatible, easily reproducible in less time, biodegradable and should be able to generate complex three-dimensional (3D) structures to mimic the native tissue structures. Click chemistry offers the much-needed multifunctional hydrogel materials which are interesting biomaterials for the tissue engineering and bioprinting inks applications owing to their excellent ability to form hydrogels with printability instantly and to retain the live cells in their 3D network without losing the mechanical integrity even under swollen state. METHODS: In this review, we present the recent developments of in situ hydrogel in the field of click chemistry reported for the tissue engineering and 3D bioinks applications, by mainly covering the diverse types of click chemistry methods such as Diels–Alder reaction, strain-promoted azide-alkyne cycloaddition reactions, thiol-ene reactions, oxime reactions and other interrelated reactions, excluding enzyme-based reactions. RESULTS: The click chemistry-based hydrogels are formed spontaneously on mixing of reactive compounds and can encapsulate live cells with high viability for a long time. The recent works reported by combining the advantages of click chemistry and 3D bioprinting technology have shown to produce 3D tissue constructs with high resolution using biocompatible hydrogels as bioinks and in situ injectable forms. CONCLUSION: Interestingly, the emergence of click chemistry reactions in bioink synthesis for 3D bioprinting have shown the massive potential of these reaction methods in creating 3D tissue constructs. However, the limitations and challenges involved in the click chemistry reactions should be analyzed and bettered to be applied to tissue engineering and 3D bioinks. The future scope of these materials is promising, including their applications in in situ 3D bioprinting for tissue or organ regeneration.

Síntese e funcionalização de compostos organoenxofre: sulfóxidos, sulfetos e N-sulfinil iminas / Synthesis and functionalization of organosulfur compounds: sulfoxides, sulfides and N-sulfinyl imines

Neste trabalho promovemos a síntese de sulfóxidos vinílicos ?-substituídos através da reação de acoplamento cruzado de Suzuki-Miyaura. Também foi feita a síntese de sulfóxidos enínicos inéditos, pela adição do nucleófilo no carbono ß-sulfóxido. Esses compostos eram passíveis de serem submetidos a reação de rearranjo de Pummerer aditivo e assim gerarem uma pequena biblioteca de compostos α-tioaldeídos. Um desses aldeídos sintetizados foi empregado na reação de formação de uma imina propargílica, com consequente reação de CuAAC formando iminas triazólicas. Outras iminas arílicas foram sintetizadas, passando por uma etapa de redução, com intuito de se obter a amina livre, para que fosse feita a reação de ciclização com auxílio de um agente eletrofílico. Outra classe de composto organoenxofre foi sintetizada, as N-sulfinil imina, que após a reação de acoplamento cruzado de Sonogashira, com consequente remoção de um grupo protetor e a formação do anel heterocíclico, foram obtidos compostos triazólicos N-sulfinil imínicos.

In this work we promote the synthesis of α-substituted vinylic sulfoxides through the Suzuki-Miyaura cross coupling reaction. Also the synthesis of unpublished enynic sulfoxides was made, by the addition of the nucleophile in the ß-sulfoxide carbon. These compounds were susceptible to additive Pummerer rearragement reaction and thus generated a small library of compounds. One of these aldehydes synthesized was used in the formation reaction of a propargyl imine, with consequent CuAAC reaction, forming triazol imines. Other aryl imines were synthesized, undergoing a reduction step, in order to obtain the free amine, so that the cyclization reaction was carried out with the aid of an electrophilic agent. Another class of organosulfur compound was synthesized, the N-sulfinyl imine, which after the Sonogashira cross-coupling reaction, with consequent removal of a protecting group and formation of the heterocyclic ring, N-sulfinyl imine triazolic compounds were obtained.

Click-Functionalized Fluorescent Nanoprobes with Folate Receptor-Targeting Ability for Cancer Cell Imaging / 分析化学

Folate receptor ( FR )-targeted fluorescent nanoprobes ( RSiNPs-Folate ) were constructed by modifying Rubpy-doped silica nanoparticles ( RSiNPs) with folic acid ( FA) based on click chemistry coupling method, which was successfully used for cancer cell imaging. Firstly, RSiNPs were prepared by St?ber method and modified with azide groups through the hydrolysis of silane coupling agents ( Az-PTES ) , then propargyl folate were conjugated onto the nanoparticle surfaces via click reaction. It was demonstrated that the FA-functionalized nanoprobes were successfully prepared by monitoring the characteristic peak of the azide group at 2105 cm-1 before and after coupling. In the condition of physiological pH, the nanoprobes exhibited strong red emission at 601 nm when excited at the 458 nm excitation wavelength. The cell imaging results showed that RSiNPs-Folate could effectively target FR-positive HeLa cells, while no obvious fluorescence was observed for FR-negative A549 cells. The receptor-mediated imaging mechanism was confirmed by free FA competition experiments. More importantly, HeLa cells could be selectively recognized and imaged in the mixing cell system. Compared with the carbodiimide conjugation protocols, the click-functionalized nanoprobes had many advantages such as simple synthesis procedures, mild reaction conditions and high yields, which could be potentially used for fluorescent labeling and imaging of different cancer cells.

Legumain-responsive functional gold nanoparticles for drug targeting delivery and treatment of subcutaneous xenograft tumor / 药学学报

Legumain, a kind of asparaginyl endopeptidase, is overexpressed in highly metastatic and highly aggressive tumor, which can undergo an enzymatic hydrolysis of substrates. We proposed a legumain-responsive functional gold nanoparticle (GNP) drug delivery system (GNPs-A&C), which was consist of Ala-Ala-Asn-Cys-Lys (AK) modified GNPs (GNPs-AK) and 2-cyano-6-aminobenzothiazole (CABT) modified GNPs (GNPs-CABT). In the circulation system, the GNPs-A&C could passively target to the tumor site through the enhanced permeability and retention (EPR) effect. Then the overexpressed legumain specifically cleave the peptide to exposure the 1,2-thiolamino group, which could take place click reaction with the cyano group of CABT, leading to the aggregation of two GNPs, these aggregates of GNPs with increased size were more likely to retain within tumor site. In vivo fluorescent imaging demonstrated GNPs-A&C could acquire an enhanced accumulation in legumain-overexpressed C6 tumor. Importantly, after tethering DOX, the GNPs-DOX-A&C showed an excellent anti-tumor effect with reduced cardiotoxicity.

Preparation and characterization of tumor targeting doxorubicin liposomesmodified via click chemistry / 中国药科大学学报

@#In this study, octreotide targeting doxorubicin liposome(Dox@Oct-L)was prepared by modifying cholesterol with azide group to prepare azide-modified doxorubicin liposome(Dox@N3-L), followed by click reaction on the vehicle surface with alkyne-modified octreotide. HPLC chromatographic determination showed that octreotide was successfully attached to drug loaded liposome. No significant effect of click modification on the drug loaded within liposome was detected, and the entrapment efficiency of Dox@Oct-L was 99. 8%. Dox@Oct-L showed improved in vitro anti-tumor activity against HepG2 cell when compared with Dox@N3-L, demonstrating that Dox@Oct-L possessed targeting ability against HepG2 cell. Therefore, the click chemistry in modification of drug-loading carrier surface is gentle and efficient, providing the possibility to functional modification in drug-loading carrier surface convieniently.

Study on in vitro controlled release of danshensu based on PEG modified of mesoporous silica nanoparticles / 中草药

Objective: To prepare a series of polyethylene (PEG)-modified mesoporous silica nanoparticles (MSNs-PEG) used for danshensu delivery carrier. Methods: By the co-hydrolysis method with silica coupling agent, the content of the azide groups was controlled into MSNs. The structures of MSNs-PEG were characterized by FTIR, XRD, and TEM analyses. The results showed that PEG chains have been grafted on the surface of MSNs. The safety of MSNs-PEG carrier was preliminarily evaluated by MTT, the release rule of MSNs-PEG was investigated by in vitro release experiment. Results: PEG can be effectively and controlled grafted onto MSNs. The MSNs-PEG have the good stability in aqueous solution. The loading rate of MSNs-PEG was higher in the experimental results of danshensu. The drug loading and entrapment efficiency were 6.8 % and 22.8 %. The graft of PEG could change the release of the drug, which could effectively prolong the time of drug release. And with the increase of the amount of PEG (mass fraction), the release time of danshensu could be prolonged effectively. Conclusion: The click chemistry method is easy to control the PEG graft content, and effectively controls the release rate of danshensu.

Synthesis and anti-tumor activity of novel histone deacetylase inhibitors based on dihydropyridin-2-one scaffold / 药学学报

To discover novel dihydropyridin-2-one derivatives with higher HDAC inhibitory activity and subtype selectivity, twenty-seven dihydropyridin-2-one derivatives containing triazole unit were synthesized via click chemistry. The structures of these compounds have been confirmed by IR, 1H NMR and HR-MS spectra. Preliminary in vitro pharmacological tests showed that these compounds potently inhibited HDAC1 and HDAC6, which also displayed significant antiproliferative effect on five cancer cells, and most of them were better than that of the parent compound 1A and drug SAHA. Specifically, compound 18g exhibited most potent anti-HDAC1 activity, and also showed the greatest potency against PC-3 and HepG2. Additionally, all compounds were nontoxic to health RWPE-1 and VERO cells, while SAHA showed essential toxicity.

Development of a novel method to evaluate sialylation of glycoproteins and analysis of gp96 sialylation in Hela, SW1990 and A549 cell lines

BACKGROUND: Glycoproteins play a critical role in the cellular activities of eukaryotes. Sialic acid is typically the outermost monosaccharide of glycolipids and glycoproteins, and is necessary for normal development. RESULTS: A strategy based on avidin-biotin affinity was established to enrich sialylated glycoproteins from HeLa cervical carcinoma, SW1990 pancreatic adenocarcinoma, and A549 lung adenocarcinoma cells. Using HPLC-MS/MS, western blot, real-time PCR, and enzyme-linked immunosorbent assay, gp96 was identified in all three cell lines. No significant difference in the protein expression of gp96 was detected at the whole cell level, but the amount of bioti-nylated gp96 in SW1990 cells was 30-40 % lower than that in A549 and HeLa cells, and the amount of sialylated gp96 in SW1990 cells was 30 % lower than that in A549 and HeLa cells. Immunoblotting results showed that the expression of sialyltransferase proteins in the total cell lysates from HeLa and A549 cells were higher than that in SW1990 cells. CONCLUSIONS: We established a new method for investigating the expression and sialylation of glycoproteins using metabolic labeling, click chemistry, and avidin-biotin affinity. We successfully used this method to purify sialylated glycoproteins from cancer cell lines. Our results showed that the levels of gp96 sialylation varied across different cancer cell lines, and this may be because of differences in sialyltransferase expression.