Degradation of rhodamine B by persulfate activated with green tea iron nanoparticles.

Green iron tea nanoparticles (GT-Fe NPs) were used as persulfate(PS) activators to oxidize rhodamine B (RhB) in this study. Optimized oxidative degradation condition was 0.033 mM Fe, 5 mM PS at pH 3.0 and 298 K with an initial RhB content of 50 mg/L. After 120 min of RhB degradation utilizing GT-Fe NPs activated PS, 99% of RhB reduction was achieved, while 98% RhB reduction with PS activated by citric acid-Fe2+(CA-Fe) with the same amount of Fe2+. This RhB reduction was due to the delayed release of Fe(II) in the GT-Fe NPs. The addition of GT-Fe NPs enhanced the synthesis of OH· and SO4-· while inhibiting the formation of O2-·. A possible RhB degradation pathway was the chromophore destruction and ring-opening processes using GT-Fe NPs/PS, which produced a range of low molecular weight carboxylic acids (oxalic acid, lactic acid, acetic acid, and formic acid). GT-Fe NPs seem to be a promising persulfate activator in comparison to common activators such as CA-Fe.

Physiological synaptic activity and recognition memory require astroglial glutamine.

Presynaptic glutamate replenishment is fundamental to brain function. In high activity regimes, such as epileptic episodes, this process is thought to rely on the glutamate-glutamine cycle between neurons and astrocytes. However the presence of an astroglial glutamine supply, as well as its functional relevance in vivo in the healthy brain remain controversial, partly due to a lack of tools that can directly examine glutamine transfer. Here, we generated a fluorescent probe that tracks glutamine in live cells, which provides direct visual evidence of an activity-dependent glutamine supply from astroglial networks to presynaptic structures under physiological conditions. This mobilization is mediated by connexin43, an astroglial protein with both gap-junction and hemichannel functions, and is essential for synaptic transmission and object recognition memory. Our findings uncover an indispensable recruitment of astroglial glutamine in physiological synaptic activity and memory via an unconventional pathway, thus providing an astrocyte basis for cognitive processes.

Blinking Fluorescent Probes for Tubulin Nanoscopy in Living and Fixed Cells.

Here we report a small molecule tubulin probe for single-molecule localization microscopy (SMLM), stimulated emission depletion (STED) microscopy and MINFLUX nanoscopy, which can be used in living and fixed cells. We explored a series of taxane derivatives containing spontaneously blinking far-red dye hydroxymethyl silicon-rhodamine (HMSiR) and found that the linker length profoundly affects the probe permeability and off-targeting in living cells. The best performing probe, HMSiR-tubulin, is composed of cabazitaxel and the 6'-regioisomer of HMSiR bridged by a C6 linker. Microtubule diameter of ≤50 nm was routinely measured in SMLM experiments on living and fixed cells. HMSiR-tubulin allows a complementary use of different nanoscopy techniques for investigating microtubule functions and developing imaging methods. For the first time, we resolved the inner microtubule diameter of 16 ± 5 nm by optical nanoscopy and thereby demonstrated the utility of a self-blinking dye for MINFLUX imaging.

Photothermal-Enhanced Fenton-like Catalytic Activity of Oxygen-Deficient Nanotitania for Efficient and Safe Tooth Whitening.

The growing demand for charming smiles has led to the popularization of tooth bleaching procedures. Current tooth bleaching products with high-concentration hydrogen peroxide (HP, 30-40%) are effective but detrimental due to the increased risk of enamel destruction, tooth sensitivity, and gingival irritation. Herein, we reported a less-destructive and efficient tooth whitening strategy with a low-concentration HP, which was realized by the remarkably enhanced Fenton-like catalytic activity of oxygen-deficient TiO2 (TiO2-x). TiO2-x nanoparticles were synthesized with a modified solid-state chemical reduction approach with NaBH4. The Fenton-like activity of TiO2-x was optimized by manipulating oxygen vacancy (OV) concentration and further promoted by the near-infrared (NIR)-induced photothermal effect of TiO2-x. The TiO2-x sample named BT45 was chosen due to the highest methylene blue (MB) adsorption ability and Fenton-like activity among acquired samples. The photothermal property of BT45 under 808 nm NIR irradiation was verified and its enhancement on Fenton-like activity was also studied. The BT45/HP + NIR group performed significantly better in tooth whitening than the HP + NIR group on various discolored teeth (stained by Orange II, tea, or rhodamine B). Excitingly, the same tooth whitening performance as the Opalescence Boost, a tooth bleaching product containing 40% HP, was obtained by a self-produced bleaching gel based on this novel system containing 12% HP. Besides, negligible enamel destruction, safe temperature range, and good cytocompatibility of TiO2-x nanoparticles also demonstrated the safety of this tooth bleaching strategy. This work indicated that the photothermal-enhanced Fenton-like performance of the TiO2-x-based system is highly promising in tooth bleaching application and can also be extended to other biomedical applications.

A novel bimetallic (Fe/Bi)-povidone-iodine micro-flowers composite for photocatalytic and antibacterial applications.

The present work describes the synthesis of polyvinylpyrrolidone (PVP) assisted Fe-BiOI based Fe/Bi-povidone­iodine (Fe/Bi-P-I) micro-flowers based composite and its photocatalytic and antibacterial applications. The Fe/Bi-P-I micro-flowers-based composite material was synthesized using a simple co-precipitation method. The prepared Fe/Bi-P-I micro-flowers-based composite materials were characterized using various characterization techniques and tested against photocatalytic degradation of rhodamine B (RhB) dye and antibacterial analysis. The PVP or povidone­iodine provides more exposure of reactive sites and oxygen vacancies, which leads to a high separation rate of photoinduced charge carriers, and migration, thereby 100% of photodegradation efficiency at 1 mg/L initial concentration of RhB dye towards the synthesized P-Fe-BiOI based micro-flowers composite. Interestingly, Povidone-Iodine in Fe/Bi-P-I micro-flowers-based composite might be advantageous for antimicrobial activity against both gram-negative (E. coli), and gram-positive (S. aureus) bacterial strains. Therefore, the prepared Fe/Bi-P-I micro-flowers-based composite improved both photocatalytic degradation of organic pollutants as well as high antimicrobial activity. The method of synthesizing the Bi/Fe-P-I micro flower composite in the present study is novel, facile, and economically viable.

Oligonucleotide-capped nanoporous anodic alumina biosensor as diagnostic tool for rapid and accurate detection of Candida auris in clinical samples.

Candida auris has arisen as an important multidrug-resistant fungus because of several nosocomial outbreaks and elevated rates of mortality. Accurate and rapid diagnosis of C. auris is highly desired; nevertheless, current methods often present severe limitations and produce misidentification. Herein a sensitive, selective, and time-competitive biosensor based on oligonucleotide-gated nanomaterials for effective detection of C. auris is presented. In the proposed design, a nanoporous anodic alumina scaffold is filled with the fluorescent indicator rhodamine B and the pores blocked with different oligonucleotides capable of specifically recognize C. auris genomic DNA. Gate opening modulation and cargo delivery is controlled by successful DNA recognition. C. auris is detected at a concentration as low as 6 CFU/mL allowing obtaining a diagnostic result in clinical samples in one hour with no prior DNA extraction or amplification steps.

Mechanistic investigations of antitumor activity of a Rhodamine B­oleanolic acid derivative bioconjugate.

Cancer remains a major health problem worldwide due to its high mortality rate. New therapeutic options highlight the importance of discovering new compounds that target the tumor microenvironment, interrupt angiogenesis and act selectively. The present study assessed the antitumor effect and investigated the mechanism of action of a rhodamine B­conjugated oleanolic acid derivative (RhodOA). Consequently, the compound was tested on different human tumor cell lines (A375 melanoma, A549 lung adenocarcinoma and MDA­MB­231 breast adenocarcinoma) and on a non­tumor cell line HaCaT human keratinocyte. RhodOA produced a dose­dependent decrease in tumor cell viability especially in the melanoma cells while affecting the keratinocytes less. In melanoma cells, RhodOA reduced cell migration and produced condensation of cell nuclei and of actin fibers. Furthermore, an impairment in melanoma cell mitochondrial function was observed, while the mitochondrial function of keratinocytes was left intact. In the in ovo chorioallantoic membrane model, RhodOA elicited antiangiogenic effect, without showing irritation effect on the membrane. The study provides information on the selective antitumor effect of the derivative and its ability to inhibit cellular respiration, therefore RhodOA can be classified as 'MITOCAN'.

A versatile luminescent resonance energy transfer (LRET)-based ratiometric upconversion nanoprobe for intracellular miRNA biosensing.

Rational design and fabrication of bio-nanoprobes for intracellular miRNA biosensing are highly desired for early clinical diagnosis and prognosis. Herein, we have developed a versatile LRET-based ratiometric (LBRU) nanoprobe of NaYF4:Yb,Er@NaYF4@NH2-mSiO2/rhodamine B/C-DNA sandwich-structured nanocomposites for intracellular miRNA biosensing. The nanoprobe was composed of NaYF4:Yb,Er@NaYF4 upconversion nanoparticles (energy donor) with an amino functionalized mesoporous silica shell (NH2-mSiO2), rhodamine B (acceptor) loaded into the mesopores of NH2-mSiO2, and the complementary sequences of target miRNA (denoted as C-DNA) acting as recognition species wrapped on the nanocomposite. Due to the LRET behavior between donors and acceptors, the loaded rhodamine B can quench the green upconversion emission of NaYF4:Yb,Er@NaYF4 at 540 nm completely. Moreover, it can be released from the nanocomposite in the presence of target miRNA, which blocked the LRET behavior to "turn on" the green upconversion luminescence. Besides, as the unaffected red upconversion luminescence (at 660 nm) can be used as an internal standard to provide built-in correction for environmental effects, the intensity ratio of upconversion luminescence at 540 and 660 nm (I540/I660) was employed as the output signal to afford an accurate detection of target miRNA. Due to the biocompatibility, high photostability and low auto-fluorescence background, the nanoprobe was successfully utilized to diagnose the intracellular miRNA-21 expression in MCF-7 cells via upconversion fluorescence imaging. We envision that the proposed LBRU nanoprobe has great potential applications in early cancer diagnosis.

Magnetite nanoparticle embedded Pectin-graft-poly(N-hydroxyethylacrylamide) hydrogel: Evaluation as adsorbent for dyes and heavy metal ions from waste water.

A pectin (Pec) based gel has been made by grafting N-hydroxyethylacrylamide (HEAA) on pectin using potassium peroxodisulphate as initiator and N,N-methylenebisacrylamide as crosslinker under microwave irradiation. The magnetite (Fe3O4) nanoparticles were incorporated within this gel via in situ diffusion of Fe2+ and Fe3+ followed by reaction with ammonia solution. The synthesized gel, pectin-graft-poly(N-hydroxyethylacrylamide) (Pec-g-PHEAA); and the magnetite containing composite (Pec-g-PHEAA/Fe3O4) were characterized by FTIR, TGA, XRD, BET and SEM techniques. The magnetic property measurement indicated ferromagnetic nature of the nanocomposite. The Pec-g-PHEAA and Pec-g-PHEAA/Fe3O4 systems were evaluated for removal of dye and metal ions from aqueous solution using Rhodamine 6G (R6G), a cationic dye; Cu(II) and Hg(II) ions. Both adsorbents showed significant adsorption capacity towards these species, with greater adsorption capacity in case of Pec-g-PHEAA/Fe3O4. Adsorption process is observed to follow both Langmuir and Freundlich isotherm models for R6G dye and Freundlich isotherm model for Cu(II) and Hg(II) ions. The adsorption was found to be a pseudo first order process for R6G and pseudo second order process for Cu(II) and Hg(II) ions. The positive values of ∆H0 and the negative values of ∆G0 indicated the adsorption process to be endothermic and spontaneous.

Photocatalytic degradation of Rhodamine B by zinc oxide nanoparticles synthesized using the leaf extract of Cyanometra ramiflora.

In the current study, the green synthesis of zinc oxide nanoparticles (ZnONPs) using the leaf extract of Cyanometra ramiflora and zinc acetate precursor is presented. The phyto-components of the extract aided the reduction and the formation of nanoparticles. The purified ZnONPs were characterized by UV-Vis spectroscopy, SEM, EDS, XRD, BET, and FTIR techniques. A sharp absorption maximum at 360 nm in the UV-Vis data affirmed the formation of ZnONPs. SEM image revealed the nanoflower morphology and EDS showed strong signals for zinc and oxygen elements. XRD spectrum confirmed the hexagonal wurtzite crystalline structure of size 13.33 nm. A significant large surface area of 16.27 m2/g with mesopores, was affirmed using BET analysis. FTIR substantiated the existence of the characteristic zinc and oxygen bonding vibrations at 557 cm-1, 511 cm-1 and 433 cm-1. The photocatalytic activity of the ZnONPs was examined using the pollutant dye, Rhodamine B. A remarkable degradation efficiency of 98% within 200 min was achieved under sunlight irradiation and a degradation constant of 0.017 min-1 was obtained. Therefore, ZnONPs synthesized using a cheap and abundant source - the leaf extract of C.ramiflora possibly will play a promising part in the degradation of toxic dyes present in the wastewater.

Development of a red absorbing Se-rhodamine photosensitizer and its application for bio-orthogonally activatable photodynamic therapy.

A π-extended red absorbing Se-rhodamine (Se-NR) was synthesised and characterized. By masking the amine of Se-NR as an azide, we successfully constructed a bio-orthogonally activatable photosensitizer (Se-NR-Az). Se-NR-Az was not photocytotoxic, but when activated by the Staudinger reaction, photocytotoxicity was restored.

A new colorimetric and fluorescent probe based on Rhodamine B hydrazone derivatives for cyanide and Cu2+ in aqueous media and its application in real life.

A simple selective colorimetric and fluorimetric chemosensor RD based on Rhodamine B hydrazone derivatives was designed and synthesized, which showed both colorimetric and fluorescence responses for cyanide and Cu2+ in aqueous solution with specific selectivity and high sensitivity. In the presence of cyanide, the sensor exhibited a visible color change from colorless to pale yellow by naked-eyes and rapidly produced a strong yellow fluorescence in aqueous solution. The detection limit on fluorescence response of RD sensor to CN- is down to 3.54×10-7M. In addition, compared to other metal ions such as Fe3+, Hg2+, Ag+, Ca2+, Cu2+, Co2+, Ni2+, Cd2+, Pb2+, Cr3+, Zn2+ and Mg2+ in aqueous solutions, RD could show both colorimetric and fluorescence responses rapidly for Cu2+. Notably, this sensor can be used as a molecular switch controlled by CN- and H+ cyclically. Test strips based on RD were fabricated that could be used as a convenient and efficient CN- and Cu2+ test kits. RD could detect cyanide in germinated potato, bitter almond and tap water. This chemosensor enabled detection of two ions, which do not need to rely on two different sensors.

Facile Transfer of Reverse Micelles from the Organic to the Aqueous Phase for Mimicking Enzyme Catalysis and Imaging-Guided Cancer Therapy.

Reverse micelles (RMs) with confined water pools have been applied in many fields. However, the water insolubility of RMs seriously limits the scope of their application, especially those needed to operate in aqueous environments. Here, we report the first successful transfer of RMs from the organic phase to water phase without disturbing their confined water pools and hydrophobic alkyl region. This transfer was achieved by virtue of a mild host-guest interaction between the hydrophobic tails of interfacial cross-linked reverse micelles (ICRMs) and the hydrophobic cavity of (2-hydroxypropyl)-ß-cyclodextrin (HP-ß-CD). Benefitting from the maintained confined water pools and the hydrophobic scaffold, the obtained water-soluble ICRMs served as multifunctional nanoplatforms for enzyme-mimicking catalysis and image-guided cancer therapy, which were impossible for normal RMs lacking water solubility or confined pool-buried water-soluble nanoparticles without a hydrophobic alkyl chain. This mild transfer approach thus surmounts the application obstacle of RMs and opens up new avenues for their application in aqueous environments.

Targeted and Synergic Glioblastoma Treatment: Multifunctional Nanoparticles Delivering Verteporfin as Adjuvant Therapy for Temozolomide Chemotherapy.

Despite advances in cancer therapies, glioblastoma multiforme treatment remains inefficient due to the brain-blood barrier (BBB) inhibitory activity and to the low temozolomide (TMZ) chemotherapeutic selectivity. To improve therapeutic outcomes, in this work we propose two strategies, (i) photodynamic therapy (PDT) as adjuvant treatment and (ii) engineering of multifunctional theranostic/targeted nanoparticles ( m-NPs) that integrate biotin as a targeting moiety with rhodamine-B as a theranostic agent in pluronic P85/F127 copolymers. These smart m-NPs can surmount the BBB and coencapsulate multiple cargoes under optimized conditions. Overall, the present study conducts a rational m-NP design, characterization, and optimizes the formulation conditions. Confocal microscopy studies on T98-G, U87-MG, and U343 glioblastoma cells and on NIH-3T3 normal fibroblast cells show that the m-NPs and the encapsulated drugs are selectively taken up by tumor cells presenting a broad intracellular distribution. The formulations display no toxicity in the absence of light and are not toxic to healthy cells, but they exert a robust synergic action in cancer cells in the case of concomitant PDT/TMZ treatment, especially at low TMZ concentrations and higher light doses, as demonstrated by nonlinear dose-effect curves based on the Chou-Talalay method. The results evidenced different mechanisms of action related to the disjoint cell cycle phases at the optimal PDT/TMZ ratio. This effect favors synergism between the PDT and the chemotherapy with TMZ, enhances the antiproliferative effect, and overcomes cross-resistance mechanisms. These results point out that m-NP-based PDT adjuvant therapy is a promising strategy to improve TMZ-based glioblastoma multiforme treatments.

Interaction of the anti-tuberculous drug bedaquiline with artificial membranes and rat erythrocytes.

Bedaquiline (BDQ) is a new drug from the family of diarylquinolines, which has a potent bactericidal activity against Mycobacterium tuberculosis. This paper has examined the interaction of BDQ with model membranes (liposomes and BLM) and rat erythrocytes. It was shown that BDQ (1-10 mol%) changed the thermotropic phase behavior of DMPC liposomes, leading to the lateral phase separation in the lipid bilayer and the formation of membrane microdomains. BDQ (10-50 µM) was also demonstrated to cause permeabilization of lecithin liposomes loaded with the fluorescent dye sulforhodamine B. At the same time, it did not alter the ionic conductivity of BLM. A dynamic light scattering study showed that BDQ led to the emergence of two populations of light-scattering particles in the suspension of lecithin liposomes, suggesting that an aggregation of the vesicles took place. In rat erythrocytes, BDQ was found to induce changes in their size and shape, as well as aggregation and lysis of the cells.

Silver and gold nanoparticles biosynthesized by aqueous extract of burdock root, Arctium lappa as antimicrobial agent and catalyst for degradation of pollutants.

This study presents an efficient and facile method for biosynthesis of silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) using aqueous extract of burdock root (BR), A. lappa, and their applications. The nanoparticles were characterized by ultraviolet-visible spectrophotometry, X-ray diffraction, transmission electron microscopy, energy dispersive X-ray, thermogravimetry, and differential thermal analysis. AgNPs capped the BR extract (BR-AgNPs) possessed roughly spherical geometry with an average diameter of 21.3 nm while uneven geometry of AuNPs capped the BR extract (BR-AuNPs) showed multi shapes in average size of 24.7 nm. The BR-AgNPs strongly inhibited five tested microorganism strains. In particular, the nanoparticles showed excellent catalytic activity for the conversion of pollutants within wastewater. Pseudo-first-order rate constants for the degradation of 4-nitrophenol, methyl orange, and rhodamine B were respectively found 6.77 × 10-3, 3.70 × 10-3, and 6.07 × 10-3 s-1 for BR-AgNPs and 6.87 × 10-3, 6.07 × 10-3, and 7.07 × 10-3 s-1 for BR-AuNPs. Graphical abstract ᅟ.

Biogenic synthesis of gold nanoparticles and their application in photocatalytic degradation of toxic dyes.

Plants and their extracts play an important role in the green synthesis of nanoparticles mainly because of their environmental benignity. Based on plant extracts number of metal nanoparticles have been synthesized. In our study, we report a green technique for the synthesis of gold nanoparticles using the aqueous extracts of Alpinia nigra leaves and their photocatalytic activities. The antioxidant, antibacterial and antifungal potential of the synthesized nanoparticles were also evaluated. The aqueous extract of the plant is rich in flavonoids with Total Flavonoid Content of 491mgRE/g extract. The presence of flavonoids was further confirmed through analytical High Performance Liquid Chromatography (HPLC) analysis. The A. nigra mediated syntheses of gold nanoparticles (ANL-AuNPs) were characterized by UV-Vis spectrophotometer, Fourier Transform Infrared (FTIR) Spectroscopy, X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). The crystalline nature of the ANL-AuNPs was confirmed by the powder XRD analysis. The TEM micrographs showed that the ANL-AuNPs was predominantly spherical in shape and the average particle size was 21.52 nm. The polyphenolics and other functional groups present in the aqueous extract that acted as reducing and capping agent in the synthesis of the Au-NPs were identified via FTIR spectral analysis. These green synthesized nanoparticles exhibited antioxidant activity with IC50 value of 52.16 µg/ml and showed inhibition in the growth of both gram-positive and gram-negative bacteria. The pathogenic fungus, Candida albicans was also susceptible to these nanoparticles. The ANL-AuNPs in the presence of sunlight catalyzed the degradation of the anthropogenic pollutant dyes, Methyl Orange and Rhodamine B with percent degradation of 83.25% and 87.64% respectively. The photodegradation process followed pseudo first order kinetic model. These results confirm that Alpinia nigra is a potential bioresource for the synthesis of Au-NPs with versatile applications.

A label-free fluorescent aptasensor for detection of kanamycin based on dsDNA-capped mesoporous silica nanoparticles and Rhodamine B.

Kanamycin is an aminoglycoside antibiotic that can be useful against both gram negative and positive bacteria. However, if its serum levels are not controlled properly, it can cause serious side effects like ototoxicity and nephrotoxicity. The aim of this study was to design a simple and rapid fluorescent aptasensor for detection of kanamycin, based on Aptamer/Complementary strand (dsDNA)-capped mesoporous silica nanoparticles (MSNs) and Rhodamine B as a fluorescent probe. The MSNs pores were filled with Rhodamine B and then gated with dsDNA. In the presence of kanamycin, the aptamer sequence was separated from its complementary strand (CS), so that, uncovered the pores and leading to leakage of Rhodamine B. Thus, a significant increase in the fluorescence intensity was observed. The relative fluorescence intensity showed a linearity range from 24.75 nM to 137.15 nM of kanamycin with a detection limit of 7.5 nM. The aptasensor also showed to be useful for detection of kanamycin in serum samples and was able to distinguish kanamycin from other antibiotics, resulting in a sensitive, rapid and inexpensive method for kanamycin detection.

3'-End labeling of nucleic acids by a polymerase ribozyme.

A polymerase ribozyme can be used to label the 3' end of RNA or DNA molecules by incorporating a variety of functionalized nucleotide analogs. Guided by a complementary template, the ribozyme adds a single nucleotide that may contain a fluorophore, biotin, azide or alkyne moiety, thus enabling the detection and/or capture of selectively labeled materials. Employing a variety of commercially available nucleotide analogs, efficient labeling was demonstrated for model RNAs and DNAs, human microRNAs and natural tRNA.

Solvothermal synthesis, characterization and photocatalytic property of zirconium dioxide doped titanium dioxide spinous hollow microspheres with sunflower pollen as bio-templates.

Zirconium dioxide (ZrO2) doped titanium dioxide (TiO2) spinous hollow microspheres were successfully prepared through a facile solvothermal method using sunflower pollen as bio-templates. The products were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), N2 adsorption-desorption isotherms and UV-Vis diffuse reflectance spectroscopy. It was found that the products have spinous microsphere morphology with an approximate diameter of 12 µm. The ZrO2 doped TiO2 hollow microspheres exhibited a higher photocatalytic activity in the degradation of Rhodamine B (RhB) in aqueous solutions under UV-light irradiation compared with TiO2 hollow microspheres and ZrO2-doped TiO2 particles. In particular, the removal of RhB followed pseudo-first-order kinetics, and 96.3% of RhB was degraded in 60 min under UV-light irradiation when ZrO2 doped TiO2 spinous hollow microspheres were used as the photocatalysts. Neutral and alkaline conditions were found to favor over acidic conditions for the photocatalytic degradation of RhB. Furthermore, scavenging experiments indicated that photogenerated holes (h+) and radicals (OH and O-2) were the main reactive species in the photocatalytic process using ZrO2 doped TiO2 hollow microspheres as the catalysts under UV light irradiation.