Biodecolorization and biodegradation of Reactive Green 12 textile industry dye and their post-degradation phytotoxicity-genotoxicity assessments.

The employment of versatile bacterial strains for the efficient degradation of carcinogenic textile dyes is a sustainable technology of bioremediation for a neat, clean, and evergreen globe. The present study has explored the eco-friendly degradation of complex Reactive Green 12 azo dye to its non-toxic metabolites for safe disposal in an open environment. The bacterial degradation was performed with the variable concentrations (50, 100, 200, 400, and 500 mg/L) of Reactive Green 12 dye. The degradation and toxicity of the dye were validated by high-performance liquid chromatography, Fourier infrared spectroscopy analysis, and phytotoxicity and genotoxicity assay, respectively. The highest 97.8% decolorization was achieved within 12 h. Alternations in the peaks and retentions, thus, along with modifications in the functional groups and chemical bonds, confirmed the degradation of Reactive Green 12. The disappearance of a major peak at 1450 cm-1 corresponding to the -N=N- azo link validated the breaking of azo bonds and degradation of the parent dye. The 100% germination of Triticum aestivum seed and healthy growth of plants verified the lost toxicity of degraded dye. Moreover, the chromosomal aberration of Allium cepa root cell treatment also validated the removal of toxicity through bacterial degradation. Thereafter, for efficient degradation of textile dye, the bacterium is recommended for adaptation to the sustainable degradation of dye and wastewater for further application of degraded metabolites in crop irrigation for sustainable agriculture.

The global anaerobic metabolism regulator fnr is necessary for the degradation of food dyes and drugs by Escherichia coli.

IMPORTANCE: This work has broad relevance due to the ubiquity of dyes containing azo bonds in food and drugs. We report that azo dyes can be degraded by human gut bacteria through both enzymatic and nonenzymatic mechanisms, even from a single gut bacterial species. Furthermore, we revealed that environmental factors, oxygen, and L-Cysteine control the ability of E. coli to degrade azo dyes due to their impacts on bacterial transcription and metabolism. These results open up new opportunities to manipulate the azoreductase activity of the gut microbiome through the manipulation of host diet, suggest that azoreductase potential may be altered in patients suffering from gastrointestinal disease, and highlight the importance of studying bacterial enzymes for drug metabolism in their natural cellular and ecological context.

Nanobioremediation: a bacterial consortium-zinc oxide nanoparticle-based approach for the removal of methylene blue dye from wastewater.

Industrial effluents carrying dyes are considered a major environmental threat in the present era. Methylene blue (MB) dye is one of the key dyes of the thiazine group of dyes. It is broadly used in medical, textile, and various fields and is well known for its carcinogenicity and methemoglobin nature. Bacterial and other microbes-mediated bioremediation is becoming an emerging and significant section for the treatment of wastewater. Isolated bacteria were used for the bioremediation and nanobioremediation of methylene blue dye under varying conditions and parameters. A comparative study was conducted for the remediation of methylene blue dye using bacterial consortium, potential bacteria (isolated by scale-up method), and potential bacteria within zinc oxide nanoparticles. The decolorizing ability of bacteria was analyzed by UV visible spectrophotometer after stirring and static incubation in different time intervals of the isolates. Growth parameters and environmental parameters which include pH, initial dye concentration, and dose of nanoparticles were optimized with the minimal salt medium. An enzyme assay study was also done to check the effect of dye and nanoparticles on bacterial growth and the mode of action of degradation. The authors found that potential bacteria within ZnO nanoparticles showed enhanced decolorization efficiency (95.46% at pH 8) due to the properties of nanoparticles. On the other hand, the decolorization of MB dye by potential bacteria and the bacterial consortium was about 89.08 and 76.3%, respectively, for a 10-ppm dye concentration. During the enzyme assays study, the highest activity was observed for phenol oxidase, nicotinamide adenine dinucleotide (NADH), 2,6-Dichloroindophenol(DCIP), and laccase for nutrient broth having MB dye, MB dye, and ZnO NPs, while no such change was observed for manganese peroxidase enzyme activity. Nanobioremediation is a promising approach to removing such pollutants from the environment.

Biodegradation of textile dye Rhodamine-B by Brevundimonas diminuta and screening of their breakdown metabolites.

The carcinogenic Rhodamine-B dye is recalcitrant which could cause serious hazards to human beings. Degradation with the application of unique bacterial strain is a sustainable technique. The bioremediation technique showed great potential to degrade a variety of recalcitrant pollutants like dyes. In this study, Brevundimonas diminuta, was selected for the breakdown of toxic textile dye Rhodamine-B. This bacterium showed 90-95% of degradation at the optimum conditions like 10 mg L-1 of concentration of dye, pH 7 and temperature of 30 °C. Further UV-Visible spectrophotometry, FT-IR spectral scan, GC-MS analysis depicted the breakdown products like Methyl 18-fluoro-octadec-9-enoate, Methyl 18-fluoro-octadec-9-enoate and d-Homo-24-nor-17-oxachola-20,22-diene-3,16-dione,7-(acetyloxy)-1, 23 tri-epoxy-4,4,8-trimethyl. The degradation was confirmed by the changes in the functional groups, change in molecular weight and charge to-mass ratio. These results suggested that this strain is a deserving organism for the degradation of dye compounds.

Characterization of Immobilized Magnetic Fe3O4 Nanoparticles on Raoultella Ornithinolytica sp. and Its Application for Azo Dye Removal.

A high-performance immobilized bacterial strain coated with magnetic iron oxide nanoparticles was used for Basic Blue 41 azo dye (BB 41 dye) decolorization. To create the coated bacterial strain, Raoultella Ornithinolytica sp. was isolated and identified under the accession number KT213695, then coated with manufactured magnetic iron oxide nanoparticles. SEM and SEM-EDX were used to characterize the coated bacteria and validate its morphological structure formation. The coated Raoultella Ornithinolytica sp. A1 (coated A1) generated a 95.20% decolorization for BB 41 dye at 1600 ppm starting concentration with an optimal dose of coated A1 5 mL/L, pH 8, under static conditions for 24 h at 37 °C. Continuous batch cycles were used, with BB 41 dye (1600 ppm) added every 24 h four times, to achieve a high decolorization efficiency of 80.14%. Furthermore, the metabolites of BB 41 dye biodegradation were investigated by gas chromatographic-mass spectrum analysis (GC-MS) and showed a less toxic effect on the bioindicator Artemia salina. Additionally, 5 mL/L of coated A1 demonstrated the highest decolorization rate (47.2%) when applied to a real wastewater sample after 96 h with a consequent reduction in COD from 592 to 494 ppm.

A Minority Population of Non-dye-decolorizing Bacillus subtilis enhances the Azo Dye-decolorizing Activity of Enterococcus faecalis.

Microbes live in communities in biological wastewater treatment plants and in the intestines. However, limited information is currently available on the mechanisms by which minority bacterial populations assist other bacteria besides syntrophic relationships as well as on the microbial food web. Therefore, the present study investigated the effects of non-dye-decolorizing Bacillus subtilis strain S4ga at population levels ranging between 0.04 and 4% on the activity of dye-decolorizing Enterococcus faecalis strain T6a1 using a dye decolorization assay. The results obtained revealed that the minority population of B. subtilis S4ga enhanced the dye-decolorizing activity of E. faecalis T6a1, resulting in a shorter lag time and longer active time of dye decolorization. These effects were related to redox potential values rather than O2 concentrations. Comparisons of the extracellular metabolites in individual incubations of E. faecalis T6a1 and B. subtilis S4ga and a co-incubation suggested a mutual relationship through the cross-feeding of specific amino acids (tyrosine, methionine, tryptophan, phenylalanine, valine, and leucine from B. subtilis S4ga to E. faecalis T6a1; glutamine, histidine, aspartic acid, and proline from E. faecalis T6a1 to B. subtilis S4ga). An ana-lysis of intracellular primary metabolites indicated that the arginine deiminase (ADI) pathway, an ATP-producing energy-generating process, was more strongly activated in co-incubated E. faecalis T6a1 than in E. faecalis T6a1 incubated alone. These results suggest that a co-incubation with B. subtilis S4ga promoted ATP production by E. faecalis T6a1 cells and enhanced its dye-decolorizing activity.

Expansion of Human Megakaryocyte-Lineage Progeny via Aryl Hydrocarbon Receptor Antagonism with CH223191.

Aryl hydrocarbon receptor (AhR) antagonism is known to expand human hematopoietic stem cells (HSCs). However, its regulatory effect on the lineage-skewed differentiation of HSCs has not been sufficiently studied. Here, we investigate the effect of the AhR-selective antagonist CH223191 on the regulation of HSC differentiation. Consistent with the well-known effects of AhR antagonists, CH223191 treatment increase phenotypic HSCs (Lin-CD34 + CD38-CD90 + CD45RA-) and preserves their functionality. On the other hand, CH223191 leads to an overall expansion of megakaryocyte (MK)-lineage populations, such as MK progenitors (MKps, CD34 + CD41 +), immature MKs (CD41 + CD42b-), and mature MKs (CD41 + CD42b +), and it also activates MK/platelet-associated signaling pathways. Furthermore, CH223191 expands MKps, mature MKs, and p-selectin (CD62p)-positive platelet-like particles in immune thrombocytopenia (ITP) patient bone marrow (BM). These results highlight the numerical expansion of human MK-lineage progeny through AhR antagonism with CH223191. This approach using CH2231291 may be applicable in the development of auxiliary treatment regimens for patients with abnormal thrombopoiesis.

Degradation and detoxification of reactive yellow dyes by Scedosporium apiospermum: a mycoremedial approach.

Textile industrial effluents have long enunciated the essentiality of ascertaining an efficient wastewater treatment for the removal of azo dyes given their potential disturbances on the ecosystem. Our study investigated the efficiency of the strain SKF2 among 14 other isolates, molecularly identified to be Scedosporium apiospermum, isolated by our research group from the textile effluent sludge in the degradation of two azo dyes, Reactive Yellow 145 and Remazol Yellow RR. Kinetic profiling of the degradation process revealed the decolourisation efficiency to be 94.8 and 86.9% for RY 145 and RYRR, respectively, during the declining growth phase. Laccase and polyphenol oxidase (RY 145-2.37 and RYRR-2.30 U/mL; RY 145-3.26 and RYRR-2.89 U/mL, respectively) were found to influence the biodegradation process in both the dyes than the other examined fungal degradative enzymes. The metabolic pathway predicted with the aid of GC-MS analysis identified the degraded metabolites to be smaller molecular weight non-toxic products. Assessment of toxicity via brine shrimp lethality assay (RY 145-23.3% and RYRR-16.7%, respectively) and seed germination assay (RY 145-96.7% and RYRR-83.3%) further solidified the detoxified status of both the dyes after biodegradation. The experimental data thus substantiated the expediency of S. apiospermum SKF2 in the degradation of textile azo dyes and its further employment in the bioremediation of textile wastewaters for agricultural applications and ecological recycling.

Role of human glutathione transferases in biotransformation of the nitric oxide prodrug JS-K.

Nitric oxide (NO) plays a prominent physiological role as a low-molecular-mass signal molecule involved in diverse biological functions. Great attention has been directed to pharmacologically modulating the release of NO for various therapeutic applications. We have focused on O2-(2,4-dinitrophenyl) 1-[(4-ethoxycarbonyl)piperazin-1-yl]diazen-1-ium-1,2-diolate (JS-K) as an example of diazeniumdiolate prodrugs with potential for cancer chemotherapy. JS-K is reportedly activated by glutathione conjugation by glutathione transferase (GST), but the scope of activities among the numerous members of the GSTome is unknown. We demonstrate that all human GSTs tested except GST T1-1 are active with JS-K as a substrate, but their specific activities are notably spanning a > 100-fold range. The most effective enzyme was the mu class member GST M2-2 with a specific activity of 273 ± 5 µmol min-1 mg-1 and the kinetic parameters Km 63 µM, kcat 353 s-1, kcat/Km 6 × 106 M-1 s-1. The abundance of the GSTs as an ensemble and their high catalytic efficiency indicate that release of NO occurs rapidly in normal tissues such that this influence must be considered in clarification of the tumor-killing effect of JS-K.

Photoswitches for controllable RNA binding: a future approach in the RNA-targeting therapy.

RNA is an emerging drug target that opens new perspectives in the treatment of viral and bacterial infections, cancer and a range of so far incurable genetic diseases. Among the various strategies towards the design and development of selective and efficient ligands for targeting and detection of therapeutically relevant RNA, photoswitchable RNA binders represent a very promising approach due to the possibility to control the ligand-RNA and protein-RNA interactions by light with high spatiotemporal resolution. However, the field of photoswitchable RNA binders still remains underexplored due to challenging design of lead structures that should combine high RNA binding selectivity with efficient photochemical performance. The aim of this highlight article is to describe the development of photoswitchable noncovalent RNA binders and to outline the current situation and perspectives of this emerging interdisciplinary field.

Study of photocatalytic activity of green synthesized nickel oxide nanoparticles in the degradation of acid orange 7 dye under visible light.

Environmental pollution is one of the most important problems that human beings face. Today, nanotechnology has played an important role in green chemistry and the use of nanoparticles in the removal of environmental pollutants is one of the newest methods of removing pollutants in the world. So, in this study, Nickel oxide nanoparticles (NiO NPs) of this work were successfully synthesized via a green method by the usage of nickel nitrate hexahydrate as the source of metal and Biebersteinia multifida extract as the stabilizing agent throughout different annealing temperatures. The physicochemical properties of the obtained NiO NPs were characterized through the application of scanning electron microscopy (SEM), energy dispersive X-ray (EDX), powder X-ray diffraction (PXRD), ultraviolet visible (UV-vis), and Raman analysis. According to the results of SEM and PXRD, the prepared product contained a satisfying distribution and very fine cubic structure with minimal accumulation. The average crystal size of prepared nanoparticles was obtained 54-58 nm. The energy band gap of synthesized NiO NPs was calculated 3-3.7 using Tauc equation. The photocatalytic performance of NiO NPs was investigated under visible light through the decolourization reaction of acid orange 7 (AO7) dye in aqueous solution. Being composed at 300 °C of annealing temperature, these nanoparticles exhibited excellent adsorption and photocatalytic activity (90.2%) toward AO7 dye. Therefore, it can be indicated that the synthesized NiO NPs demonstrated an excellent dispersion in dye solution, as well as considerable photocatalytic activity.

In-Situ Encapsulation of Protein into Nanoscale Hydrogen-Bonded Organic Frameworks for Intracellular Biocatalysis.

Hydrogen-bonded organic frameworks (HOFs) are porous materials with great potential for biological applications. The self-assembly of HOFs and biomacromolecules, however, is challenging. We report herein the self-assembly of nanoscale HOFs (nHOFs) to encapsulate protein for intracellular biocatalysis. The self-assembly of tetrakis(4-amidiniumphenyl)methane and azobenzenedicarboxylate can encapsulate protein in situ to form protein@nHOFs under mild conditions. This strategy is applicable to proteins with different surface charge and molecular weight, showing a high protein encapsulation efficiency and minimal effect on protein activity. A cellular delivery study shows that the protein@TA-HOFs can efficiently enter cells and retain enzyme activity for biochemical catalysis in living cells for neuroprotection. Our strategy paves new avenues for interfacing nHOFs with biological settings and sheds light on expanding nHOFs as a platform for biomacromolecule delivery and disease treatment.

Azo modified hyaluronic acid based nanocapsules: CD44 targeted, UV-responsive decomposition and drug release in liver cancer cells.

Herein, we demonstrate a novel UV-induced decomposable nanocapsule of natural polysaccharide (HA-azo/PDADMAC). The nanocapsules are fabricated based on layer-by-layer co-assembly of anionic azobenzene functionalized hyaluronic acid (HA-azo) and cationic poly diallyl dimethylammonium chloride (PDADMAC). When the nanocapsules are exposed to 365 nm light, ultraviolet photons can trigger the photo-isomerization of azobenzene groups in the framework. The nanocapsules could decompose from large-sized nanocapsules to small fragments. Due to their optimized original size (~180 nm), the nanocapsules can effectively avoid biological barriers, provide a long blood circulation and achieve high tumor accumulation. It can fast eliminate nanocapsules from tumor and release the loaded drugs for chemotherapy after UV-induced dissociation. Besides, HA is an endogenous polysaccharide that shows intrinsic targetability to CD44 receptors on surface of cancer cells. The intracellular experiment shows that the HA-azo/PDADMAC nanocapsules with CD44 targeting ability and UV-controlled intracellular drug release are promising for cancer chemotherapy.

Novel photochromic inhibitor for mitotic kinesin Eg5 which forms multiple isomerization states.

The mitotic kinesin Eg5 is a plus-end directed homotetrameric molecular motor essential for the formation of bipolar spindles during cell division. Kinesin Eg5 is overexpressed in cancer cells and hence considered as a target for cancer therapy; the inhibitors specific for Eg5 have been developed as anticancer drugs. In this study, we synthesized a novel functional photoresponsive inhibitor composed of spiropyran and azobenzene derivatives to control Eg5 function with multistage inhibitory activity accompanied by the formation of different isomerization states. The photochromic inhibitor spiropyran-sulfo-azobenzene (SPSAB) exhibited three isomerization states: spiro (SP)-trans, merocyanine (MC)-cis and MC-trans, upon exposure to visible light, ultraviolet and in the dark, respectively. SPSAB-induced reversible changes in the inhibitory activity of ATPase and motor activities correlating with photoisomerization among the three states. Among the three isomerization states of SPSAB, the SP-trans isomer showed potent inhibitory activity at an IC50 value of 30 µM in the basal ATPase assay. MC-trans and MC-cis exhibited less inhibitory activity at IC50 values of 38 and 86 µM, respectively. The results demonstrated that the novel photochromic inhibitor enabled precise control of Eg5 function at three different levels using light irradiation.

Decolorization and detoxification of different azo dyes by Phanerochaete chrysosporium ME-446 under submerged fermentation.

Azo dyes are widely used in the textile industry due to their resistance to light, moisture, and oxidants. They are also an important class of environmental contaminant because of the amount of dye that reaches natural water resources and because they can be toxic, mutagenic, and carcinogenic. Different technologies are used for the decolorization of wastewater containing dyes; among them, the biological processes are the most promising environmentally. The aim of this study was to evaluate the potential of Phanerochaete chrysosporium strain ME-446 to safely decolorize three azo dyes: Direct Yellow 27 (DY27), Reactive Black 5 (RB5), and Reactive Red 120 (RR120). Decolorization efficiency was determined by ultraviolet-visible spectrophotometry and the phytotoxicity of the solutions before and after the fungal treatment was analyzed using Lactuca sativa seeds. P. chrysosporium ME-446 was highly efficient in decolorizing DY27, RB5, and RR120 at 50 mg L-1, decreasing their colors by 82%, 89%, and 94% within 10 days. Removal of dyes was achieved through adsorption on the fungal mycelium as well as biodegradation, inferred by the changes in the dyes' spectral peaks. The intensive decolorization of DY27 and RB5 corresponded to a decrease in phytotoxicity. However, phytotoxicity increased during the removal of color for the dye RR120. The ecotoxicity tests showed that the absence of color does not necessarily translate to an absence of toxicity.

Biodegradation and decolourization of methyl red by Aspergillus versicolor LH1.

Azo dyes constitute a significant environmental burden due to its toxicity, carcinogenicity, and hard biodegradation. The report here is focused on the decolorization and degradation treatment of azo dye methyl red (MR). Decolorization of MR using Aspergillus versicolor LH1 isolated from activated sludge was investigated. The maximum decolorization rate of 92.3% was obtained under the optimized conditions of sucrose as carbon source, 5d incubation age, pH 6.0, 140 mg/L initial concentration of MR and 2.5 g/L initial concentration of NaNO3. Biodegradation products of MR were investigated using HPLC-MS, FTIR, and GC-MS assays. It was revealed the three bonds of -C-N = in MR aromatic nucleus were disrupted, and benzoic acid was detected. Micronucleus test with Glycine max L. and Vicia faba L. demonstrated that MCN‰ (micronucleus permillage) of MR metabolites was less than MR solution. These findings provided evidence that A. versicolor LH1 is a candidate for MR degradation in industrial wastewater treatment.

NADPH diaphorase detects S-nitrosylated proteins in aldehyde-treated biological tissues.

NADPH diaphorase is used as a histochemical marker of nitric oxide synthase (NOS) in aldehyde-treated tissues. It is thought that the catalytic activity of NOS promotes NADPH-dependent reduction of nitro-blue tetrazolium (NBT) to diformazan. However, it has been argued that a proteinaceous factor other than NOS is responsible for producing diformazan in aldehyde-treated tissues. We propose this is a NO-containing factor such as an S-nitrosothiol and/or a dinitrosyl-iron (II) cysteine complex or nitrosated proteins including NOS. We now report that (1) S-nitrosothiols covalently modify both NBT and TNBT, but only change the reduction potential of NBT after modification, (2) addition of S-nitrosothiols or ß- or α-NADPH to solutions of NBT did not elicit diformazan, (3) addition of S-nitrosothiols to solutions of NBT plus ß- or α-NADPH elicited rapid formation of diformazan in the absence or presence of paraformaldehyde, (4) addition of S-nitrosothiols to solutions of NBT plus ß- or α-NADP did not produce diformazan, (5) S-nitrosothiols did not promote NADPH-dependent reduction of tetra-nitro-blue tetrazolium (TNBT) in which all four phenolic rings are nitrated, (6) cytoplasmic vesicles in vascular endothelial cells known to stain for NADPH diaphorase were rich in S-nitrosothiols, and (7) procedures that accelerate decomposition of S-nitrosothiols, markedly reduced NADPH diaphorase staining in tissue sections subsequently subjected to paraformaldehyde fixation. Our results suggest that NADPH diaphorase in aldehyde-fixed tissues is not enzymatic but is due to the presence of NO-containing factors (free SNOs or nitrosated proteins such as NOS), which promote NADPH-dependent reduction of NBT to diformazan.

Biological treatment of non-biodegradable azo-dye enhanced by zero-valent iron (ZVI) pre-treatment.

Zero-valent iron (ZVI) pre-treatment in sequential strategy for removal of non-biodegradable azo-dye Orange II by activated-sludge was quantitatively examined. The decolorization and TOC (total organic carbon) removal of Orange II by ZVI pre-treatment were examined in the ranges of pH from 3 to 11 and ZVI dosage from 500 to 2000 mgL-1. While the decolorization was enhanced with decreasing pH and the optimal pH for decolorization was found at pH 3, the TOC removal rate at pH 3 remained at 22.2% and the maximum TOC removal rate of 78.2% was obtained at pH 4. The decolorization and TOC removal of Orange II were monotonously increased with increasing ZVI dosage. To quantify the ZVI pre-treatment, the contributions of redox degradation, complexation/precipitation and adsorption to TOC removal by ZVI were defined. Novel kinetic models for the ZVI pre-treatment and activated-sludge post-treatment were developed. The proposed kinetic models satisfactorily predicted the transitional behaviors of the ZVI pre-treatment and activated-sludge post-treatment and the contributions of redox degradation, complexation/precipitation and adsorption to TOC removal by the ZVI pre-treatment. The complete removal of non-biodegradable azo-dye Orange II of 300 mgL-1 was accomplished by 78.2% removal after 360 min ZVI pre-treatment with the ZVI dosage of 1000 mgL-1 at pH 4 and subsequently 21.8% removal after 480 min activated-sludge post-treatment. The ZVI pre-treatment integrated with activated-sludge post-treatment was proved to be an effective strategy for treating non-biodegradable pollutants.

Characterization of the biosorption of fast black azo dye K salt by the bacterium Rhodopseudomonas palustris 51ATA strain

BACKGROUND: Removal of dyes from wastewater by microorganisms through adsorption, degradation, or accumulation has been investigated. Biological methods used for dye treatment are generally always effective and environmentally friendly. In this study, biosorption of the Fast Black K salt azo dye by the bacterium Rhodopseudomonas palustris 51ATA was studied spectrophotometrically, at various pH (2­10), temperatures (25°C, 35°C, and 45°C) and dye concentrations (25­400 mg L-1). RESULTS: The bacterial strain showed extremely good dye-removing potential at various dye concentrations. IR studies at different temperatures showed that the dye was adsorbed on the bacterial surface at lower temperatures. Characteristics of the adsorption process were investigated by Scatchard analysis at 25°C and 35°C. Scatchard analysis of the equilibrium binding data for the dye on this bacterium gave rise to linear plots, indicating that the Langmuir model could be applied. The regression coefficients obtained for the dye from the Freundlich and Langmuir models were significant and divergence from the Scatchard plot was observed. CONCLUSION: The adsorption behavior of the dye on this bacterium was expressed by the Langmuir, Freundlich, and Temkin isotherms. The adsorption data with respect to various temperatures provided an excellent fit to the Freundlich isotherm. However, when the Langmuir and Temkin isotherm models were applied to these data, a good fit was only obtained for the dye at lower temperatures, thus indicating that the biosorption ability of R. palustris 51ATA is dependent on temperature, pH, and dye concentration.

Precisely Traceable Drug Delivery of Azoreductase-Responsive Prodrug for Colon Targeting via Multimodal Imaging.

We report the development of an azoreductase-responsive prodrug AP-N═N-Cy in which the precursor compound AP, a readily available podophyllotoxin derivative, is linked with a NIR fluorophore (Cy) via a multifunctional azobenzene group. This type of azo-based prodrug can serve as not only an azoreductase-responsive NIR probe to real-time tracking of the drug delivery process but also a delivery platform for an anticancer compound (AdP). We have shown that cleavage of the multifunctional azobenzene group in AP-N═N-Cy only occurred in the presence of azoreductase, which specifically secretes in the colon, resulting in direct release of AdP through an in situ modification of a phenylamino group on the precursor AP. Moreover, introduction of the azobenzene group endows the prodrug with an unique fluorescence "off-on" property and served as a switch to "turn on" the fluorescence of Cy as consequence of a self-elimination reaction with breakage of an azo bond. Such a prodrug can be administered orally and exhibit high stability and low toxicity before arriving at the colon. In view of the synchronism of drug release and the fluorescence turn-on process, the fluorescence imaging method was utilized to precisely trace drug delivery in vitro, ex vivo, and in vivo. Distinguishingly, the biodistribution of AdP and Cy in various tissues was further precisely mapped at the molecular level using imaging mass spectrometry. To the best of our knowledge, this is the first time that the in vivo real-time precise tracking of the colon-specific drug release and biodistribution was reported via a multimodal imaging method.