Highly sensitive photoelectrochemical detection of bleomycin based on Au/WS2 nanorod array as signal matrix and Ag/ZnMOF nanozyme as multifunctional amplifier.

An ultrasensitive photoelectrochemical (PEC) biosensor was constructed based on gold nanoparticles (Au NPs)/tungsten sulfide nanorod array (WS2 NA) photoelectrode as the PEC matrix and silver nanoparticles/flake-like zinc metal-organic framework (Ag/ZnMOF) nanozyme with the peroxidase mimetic enzyme property for sensitive detection of bleomycin (BLM). In particular, Au/WS2 and Ag/ZnMOF were linked by thiolate DNA1 and DNA2 strand, respectively, and the Au/WS2-Ag/ZnMOF probe was prepared via hybridization reaction between the two DNAs. The introduction of Ag/ZnMOF in the probe offers two functions: i) the steric hindrance effect can effectively impede electron transport and reduce the photocurrent; ii) Ag/ZnMOF nanozyme can also be used as mimic peroxidase to effectively catalyze 3,3-diaminobenzidine (DAB) to produce the relevant precipitation, which will further reduce photocurrent and eliminate false positive signals. When BLM exists, BLM with Fe2+ as irreversible cofactor can specifically recognize and cleave of the 5'-GC-3' active site of DNA2, resulting in reduced precipitation deposited on the electrode and recovery of PEC signal. The highly sensitive PEC biosensor exhibits a the linear strategy from 0.5 nM to 500 nM with a detection limit down to 0.18 nM. Further, the unique strategy was conducted in biological samples for BLM detection with satisfactory consequence, offering available and efficient pathway for disease diagnosis.

An efficient procedure for preparing high-purity pingyangmycin and boanmycin from Streptomyces verticillus var. pingyangensis fermentation broth via macroporous cation-exchange resin and subsequent reversed-phase preparative chromatography.

Pingyangmycin (PYM) and boanmycin (BAM), two individual components of bleomycin (bleomycin A5 and bleomycin A6), are glycopeptide antitumor antibiotics. An efficient procedure for the preparation of PYM and BAM from Streptomyces verticillus var. pingyangensis fermentation broth using macroporous cation-exchange (MCE) resin followed by medium-pressure preparative liquid chromatography (MPLC) based on monodisperse poly(styrene-co-divinylbenzene) (p(st-dvb)) microspheres was investigated in this paper. Nine frequently used MCE resins were screened by static adsorption and desorption to enrich PYM and BAM fromthe fermentation broth, and D157 resin was found to be the most effective. After one run of column-based dynamic adsorption and desorption, the contents of PYM and BAM were increased by factors of 13.8 and 12.1 with recovery yields of 84.21% and 81.47%, respectively. The enriched samples were subjected to MPLC with columns prepacked with the PolyRP 10-300 microspheres. The operational parameters of the MPLC, including the stationary phase and mobile phase compositions, sample/stationary phase ratio, sample loading scale and flow rate, were screened and optimized. The results showed that the separation and purification for PYM and BAM by MPLC were dramatically improved with a mobile phase modifier of 0.15 mol/L ammonium chloride aqueoussolution, a flow rate of 10 mL/min and a sample/stationary phase ratio of 1.0:100 (m/v, g/mL), and PYM and BAM with purities of more than 98.65% and 99.12% were obtained, respectively. The total recoveries of PYM and BAM reached 75.38% and 70.31%. The separation and purification method is simple, efficient, energy-saving, environmentally friendly and suitable for the large-scale preparation of high-purity PYM and BAM from Streptomyces verticillus var. pingyangensis fermentation broth.

Dual-mode visible light-induced aptasensing platforms for bleomycin detection based on CdS-In2S3 heterojunction.

CdS-In2S3 heterojunction with enhanced photoelectrochemical (PEC) performance was synthesized to construct dual-mode visible light-induced biosensors for highly sensitive and selective detection of bleomycin (BLM). Due to improved absorption in the visible region and suppressed recombination of electron-hole pairs in the heterojunction, CdS-In2S3 composite exhibited enhanced photocurrent response under visible light illumination. Using CdS-In2S3 as photoactive materials and BLM-binding aptamer as recognition element, a PEC aptasensor displaying a declined photocurrent response to BLM was facilely constructed, which was linear to BLM concentration in the range of 5.0-250 nM. On the other hand, the CdS-In2S3 photoanode was employed to construct a photofuel cell (PFC). In such a PFC, the oxidation of water on CdS-In2S3 photoanode under visible light illumination and the reduction of oxygen on Pt cathode led to the generation of electricity. When BLM-binding aptamer was immobilized on CdS-In2S3 photoanode, the output power of the PFC was inversely proportional to the logarithm of BLM concentration from 10 to 250 nM, offering a visible light-induced self-powered sensing platform for BLM detection. Both of the proposed sensors showed high selectivity, good reproducibility and high stability. They were successfully applied to the determination of BLM in human serum samples.

Copper(II)-based metal affinity chromatography for the isolation of the anticancer agent bleomycin from Streptomyces verticillus culture.

The glycopeptide-based bleomycins are structurally complex natural products produced by Streptomyces verticillus used in combination therapy against testicular and other cancers. Bleomycin has a high affinity towards a range of transition metal ions with the 1:1 Fe(II) complex relevant to its mechanism of action in vivo and the 1:1 Cu(II) complex relevant to its production from culture. The affinity between Cu(II) and bleomycin was the underlying principle for using Cu(II)-based metal affinity chromatography in this work to selectively capture bleomycin from crude S. verticillus culture. A solution of standard bleomycin was retained at a binding capacity of 300 nmol mL(-1) on a 1-mL bed volume of Cu(II)-loaded iminodiacetate (IDA) resin at pH 9 via the formation of the heteroleptic immobilized complex [Cu(IDA)(bleomycin)]. Bleomycin was eluted from the resin at pH 5 as the metal-free ligand under conditions where pK(a) (IDA)

Isolation and characterization of antibiotic NC0604, a new analogue of bleomycin.

NC0604, a new analogue of bleomycin, was isolated from fermentation broth of Streptomyces verticillus var. pingyangensis n.var. The structure of NC0604 was elucidated by spectroscopic analyses. NC0604 had the same kernel structure as bleomycin, but a different terminal amine moiety determined as amidepropyl spermidine. NC0604 exhibited antibacterial activity against a wide range of bacterial species and showed cytotoxicity in vitro against human HepG(2), KB, MCF-7, HCT116, BGC-823 and MCF-7/DOX cells with IC(50) values of 1.18, 1.21, 1.41, 1.83, 2.02, 1.45 muM, respectively. The antitumor activity of NC0604 against these cells was 3~9 times higher than that of bleomycin; and the pulmonary toxicity of NC0604 was much lower than that of bleomycin.

Bleomycin A2 and B2 purification by flash chromatography for chemical and biochemical studies.

The clinically used formulation of the anticancer antibiotic, Blenoxane, is a mixture of bleomycin congeners. A new approach to separating the major A2 and B2 congeners has been developed utilizing the flash chromatography technique. A 5-6-inch column of fine mesh silica gel with a solvent system of 1% ammonium formate:methanol (2:3) was used. Low air pressure was applied to the column to increase the flow rate such that separation was complete in approximately 20 min. Reverse phase size exclusion gravity chromatography with Sephadex G-15 column bedding was an effective, rapid procedure for removal of the 1% ammonium formate, the lowest percentage practical for separating the bleomycins. This separation approach does not damage the antibiotics, as demonstrated by NMR spectroscopy, thin layer chromatography, and DNA cleaving activity. Although not as useful for detection of trace amounts of the drug in biological systems as some of the known HPLC methods, this method is excellent for separating large quantities of the drug (8-32 mg) in order to obtain congeners pure enough for synthetic, biochemical, and biophysical studies.

Stable [57Co]-bleomycin complex with a very high specific radioactivity for use at very low concentrations.

A method for the preparation of 57Co-labelled bleomycin (BLM) possessing very high specific radioactivity and suitable for use at the nanomolar concentration range is described, and validated using a biological assay. Chelation of BLM with Co(II) results in a very stable complex. However, association does not occur below the micromolar concentration range. A nanomolar [57Co]BLM solution with maximal specific radioactivity can be easily prepared, without handling unreasonable amounts of radioactivity, provided that: equimolar solutions of BLM and [57Co]Cl2 are first mixed at the micromolar concentration range and that the mixture is then diluted a thousand times to reach the nanomolar concentration range.

Demethylation and auto-oxidation of different cobalt-=bleomycin complexes.

Demethylation of Co-bleomycin A2 by heating yields three different complexes: form I and form II and "orange" Co-bleomycin-demethyl A2. These complexes can be separated by HPLC and show different 1H NMR spectra. Preparation of Co-bleomycin-demethyl A2 by chelation of bleomycin-demethyl A2 with cobalt yields a Co-bleomycin-demethyl A2, which is auto-oxidized into Co-bleomycin A1.

SF-1771, a new antibiotic related to bleomycin.

A new antibiotic, substance SF-1771, has been isolated for the fermentation broth of Streptomyces toyocaensis SF-1771. The antibiotic is highly active against Gram-positive and -negative bacteria and effective against sarcoma 180 cells of ascites type in mice. It belonged to the phleomycin-bleomycin group antibiotics, but has been differentiated from the known antibiotics by the physiochemical properties, chromatographic behaviors and amino acid analysis.

SF-1961, a new antibiotic related to bleomycin.

A new type of bleomycin group antibiotic, SF-1961 was isolated from the fermentation broth of Streptomyces species. SF-1961 possessed beta-amino-beta-(4-amino-6-carboxypyrimidin-2-yl)-propionic acid instead of its 5-methyl derivative which was a common component of bleomycins and phleomycins.