Fluorescence quenching and spectrophotometric methods for the determination of daunorubicin with meso-tera (4-sulphophenyl) porphyrin as probe

Less interference fluorescence analytical strategy: Bridging substance-triggered ratiometric sensor with convenient preparation and application

High interference and narrow application range are key of bottleneck of recent fluorescence analysis methods, which limit their wide application in the sensing field. Therefore, to overcome these disadvantages, a ratiometric fluorescence sensing system utilizing berberine (BER) and silver nanoclusters protected by dihydrolipoic acid (DHLA-AgNCs) was constructed for the first time in this work, to achieve determination of BER and daunorubicin (Dau). BER aqueous solution (non-planar conformation) has no fluorescence emission. When it was mixed with DHLA-AgNCs, the conformation of BER became planar, producing fluorescence emission at 515 nm besides the fluorescence emission peak of DHLA-AgNCs at 653 nm. With the increase of BER concentration added in system, the fluorescence intensity of BER (planar conformation) at 515 nm increased obviously and the fluorescence intensity of DHLA-AgNCs decreased slightly. Therefore, the dual emission fluorescence sensing system was constructed based on a fluorescence substance and non fluorescence substance, to achieve determination of BER. Meanwhile, based on the bridging effect of BER and fluorescence resonance energy transfer effect from Dau, the altering of two peaks intensity was utilized to achieve determination of Dau. Thus, this dual emission sensing system can not only be used for fluorescence analysis of BER and its analogues, but also based on the bridging effect of BER, allowing the determination of Dau and its analogues that could not be directly measured with silver nanoclusters, expanding the application range of traditional dual emission detection systems. Meanwhile, this system has strong anti-interference ability and low toxicity to the human body and less pollution to the sample and environment. This provides a new direction and universal research strategy for the construction of new fluorescence sensing systems in the future for the analysis of target substances that cannot be directly detected with conventional fluorescence analysis methods.

Sensitive determination of daunorubicin in plasma of children with leukemia using pH-switchable deep eutectic solvents and HPLC-UV analysis

An environmental friendly, fast, easy and inexpensive liquid-liquid microextraction (LLME) in combination with pH-switchable deep eutectic solvent (DES) method followed by HPLC was investigated for the separation and determination of daunorubicin (DNR) in human plasma samples. For this purpose, first, 9 DESs were prepared based on previous studies and their switchability in aqueous solution was evaluated by changing the pH. Non-switchable DESs were discarded and switchable DESs were used to extract DNR. The parameters affecting the extraction efficiency were optimized (DES type, volume of DES, concentration of KOH, volume of HCl, salt addition and extraction time). After optimizing the conditions and drawing the calibration curve, figures of merit were calculated. Relative standard deviations (%RSDs) based on 7 replicate with 50 μg L-1 of DNR in plasma were 2.7 for intra-day and 4.8 % for inter-day. A wide linear range from 0.15 to 200 μg L-1 was obtained. The detection limit of the method based on signal-to-noise 3 and the quantification limit of the method based on signal-to-noise 10 were 0.05 and 0.15, respectively. After spiking plasma samples with different concentrations of DNR, relative recoveries were obtained in the range of 91.0-107.8 %.

SERS Endoscopy for Monitoring Intracellular Drug Dynamics

Understanding the dynamics and distribution of medicinal drugs in living cells is essential for the design and discovery of treatments. The tools available for revealing this information are, however, extremely limited. Here, we report the application of surface-enhanced Raman scattering (SERS) endoscopy, using plasmonic nanowires as SERS probes, to monitor the intracellular fate and dynamics of a common chemo-drug, doxorubicin, in A549 cancer cells. The unique spatio-temporal resolution of this technique reveals unprecedented information on the mode of action of doxorubicin: its localization in the nucleus, its complexation with medium components, and its intercalation with DNA as a function of time. Notably, we were able to discriminate these factors for the direct administration of doxorubicin or the use of a doxorubicin delivery system. The results reported here show that SERS endoscopy may have an important future role in medicinal chemistry for studying the dynamics and mechanism of action of drugs in cells.

A sensing platform based on zinc-porphyrin derinative in hexadecyl trimethyl ammonium bromide (CTAB) microemulsion for highly sensitive detection of theophylline

A new porphyrin-based sensing platform in hexadecyl trimethyl ammonium bromide (CTAB) microemulsion is developed for highly sensitive detection of theophylline. In this sensing system, the zinc-porphyrin-cinnamic acid conjugate (Zn-TPPCA) works as fluorescence probe while theophylline can decrease fluorescence intensity of the probe. Further studies indicate the linear relationship between the fluorescence quenching value and the concentration of theophylline within a given range. And the introduction of CTAB microemulsion can greatly enhance sensibility and stability of this detecting system and facilitate the detection of theophylline. On the basis above, a highly sensitive sensing platform for theophylline is created with a low limit of detection (LOD) of 0.0083 μg mL^-1 under the optimal detection conditions. And further application of this method in determination of commercially available theophylline preparation shows excellent results. Subsequent studies on quenching mechanism indicate that static quenching appears between Zn-TPPCA and theophylline. Therefore, this work provides not only a highly sensitive method for determination of theophylline but also further evidence for creation of biosensors for drugs with porphyrin derivatives.

pH-Responsive Polyketone/5,10,15,20-Tetrakis-(Sulfonatophenyl)Porphyrin Supramolecular Submicron Colloidal Structures

In this work, we prepared color-changing colloids by using the electrostatic self-assembly approach. The supramolecular structures are composed of a pH-responsive polymeric surfactant and the water-soluble porphyrin 5,10,15,20-tetrakis-(sulfonatophenyl)porphyrin (TPPS). The pH-responsive surfactant polymer was achieved by the chemical modification of an alternating aliphatic polyketone (PK) via the Paal–Knorr reaction with N-(2-hydroxyethyl)ethylenediamine (HEDA). The resulting polymer/dye supramolecular systems form colloids at the submicron level displaying negative zeta potential at neutral and basic pH, and, at acidic pH, flocculation is observed. Remarkably, the colloids showed a gradual color change from green to pinky-red due to the protonation/deprotonation process of TPPS from pH 2 to pH 12, revealing different aggregation behavior.

Porphyrin Derivative Nanoformulations for Therapy and Antiparasitic Agents

Porphyrins and analogous macrocycles exhibit interesting photochemical, catalytic, and luminescence properties demonstrating high potential in the treatment of several diseases. Among them can be highlighted the possibility of application in photodynamic therapy and antimicrobial/antiparasitic PDT, for example, of malaria parasite. However, the low efficiency generally associated with their low solubility in water and bioavailability have precluded biomedical applications. Nanotechnology can provide efficient strategies to enhance bioavailability and incorporate targeted delivery properties to conventional pharmaceuticals, enhancing the effectiveness and reducing the toxicity, thus improving the adhesion to the treatment. In this way, those limitations can be overcome by using two main strategies: (1) Incorporation of hydrophilic substituents into the macrocycle ring while controlling the interaction with biological systems and (2) by including them in nanocarriers and delivery nanosystems. This review will focus on antiparasitic drugs based on porphyrin derivatives developed according to these two strategies, considering their vast and increasing applications befitting the multiple roles of these compounds in nature.

A novel immobilization fluorescence capillary analysis method and its applications

Fluorescence capillary analysis (FCA) realizes trace-level analysis of micro-volume samples; it is easy to operate, extremely low in analytical cost and can significantly lessen environmental pollution from analytical chemistry waste. FCA has the characteristics of green analytical chemistry and has been applied in clinical, biochemical, pharmaceutical, food safety and other fields. FCA basically involves a micro-volume glass capillary, a capillary holder and an ordinary fluorescence detector. The capillary is not only a container for chemical reaction and detection but also functions as a carrier to immobilize enzymes, gene probes or reagents; it can be used repeatedly or can be disposable. In analysis, the capillary which is modified with functional reagents sucks in a measured liquid for the reaction and is then inserted into the holder within the fluorescent detector for measurement. The immobilized FCA method has been successfully used in the determination of reduced coenzyme I, ethanol in liqueur, lactic acid in dairy products, pyruvic acid and glucose in serum, trace-level sulfated bile acid in urine, the ratio of pyruvic/lactic acid in serum, and pyruvic acid in cells as well as in DNA end-labeling and dyeing methods. Further, FCA can also be extended to capillary arrays to complete multipurpose simultaneous determinations and can be combined with mobile phones as fluorescence detectors for use in mobile health analytical technology. FCA will produce considerable social benefits in medicine, pharmacy, fermentation of food, environmental protection and other fields. Therefore, the relevant contents are presented in this tutorial review.

Determination of ultra trace amounts of metronidazole by 3-phenyl-N-[4-(10,15,20-triphenyl-porphyrin-5-yl)-phenyl]- acrylamide as the fluorescence spectral probe in CTAB microemulsion

In this work, 3-Phenyl-N-[4-(10,15,20-triphenyl-porphyrin-5-yl)-phenyl]- acrylamide (TPPCA) was synthesized for the determination of metronidazole (MTZ). It was found that the type of fluorescence quenching was static quenching determined by Stern-Volmer plot and UV absorption spectroscopy, and thermodynamic related parameters were also obtained. Furthermore, the corresponding measurement conditions: the acidity of the system, the type of surfactant, the concentration of TPPCA and the sequence of reagent addition were optimized. Under the optimal experimental conditions, the linear range of MTZ was determined to be 0.01-0.20 μg mL^-1, and the limit of detection (LOD) was 0.004 μg mL^-1. Importantly, this report provides a simple, fast, and sensitive probe for the determination of MTZ in pharmaceutical practice.

Determination of trace metallothioneins at nanomolar levels using phenanthroline-copper coordination by fluorescence spectra

A direct fluorescence spectra method was applied for the determination of metallothioneins at nanomolar levels. In Britton-Robison (B-R) buffer (pH 7.0), the interaction of bis(1,10-phenanthroline)copper(II) complex cation [Cu(phen)2](2+) and metallothioneins enhanced the fluorescence intensity of system. The fluorescence enhancement at 365 nm was proportional to the concentration of metallothioneins. The mechanism was studied and discussed in terms of the fluorescence and UV-absorption spectra. Under the optimal experimental conditions, at 365 nm, there was a linear relationship between the fluorescence intensity and the concentration of the metallothioneins in the range of 8.30 × 10(-9) - 7.70 × 10(-7) mol L(-1). The linear regression equation was ΔF = 8.96 + 38.01c (mol L(-1)), with a correlation coefficient of r = 0.998 and detection limit 2.50 × 10(-9) mol L(-1). The relative standard deviation was 0.47% (n = 11), and the average recovery 97.2%. The proposed method was successfully reliable, selective and sensitive in determining trace metallothioneins in fish visceral organ samples with the results in good agreement with those obtained by HPLC.

A highly sensitive fluorescence probe for metallothioneins based on tiron-copper complex

The fabrication of tiron-copper complex as a novel fluorescence probe for the sensitive directly detection of metallothioneins at nanomolar levels was demonstrated. In Britton-Robinson (B-R) buffer (pH 7.50), the interaction of bis(tiron)copper(II) complex cation [Cu(tiron)2](2+) and metallothioneins enhanced the fluorescence intensity of the system. The fluorescence enhancement at 347 nm was proportional to the concentration of metallothioneins. The mechanism was studied and discussed in terms of the fluorescence spectra. Under the optimal experimental conditions, at 347 nm, there was a linear relationship between the fluorescence intensity and the concentration of the metallothioneins in the range of 8.80 × 10(-9)-7.70 × 10(-7)mol L(-1), with a correlation coefficient of r=0.995 and detection limit 2.60 × 10(-9)mol L(-1). The relative standard deviation was 0.77% (n=11), and the average recovery 94.4%. The method proposed was successfully reliable, selective and sensitive in determining of trace metallothioneins in fish visceral organ samples with the results in good agreement with those obtained by HPLC.