Electrochemical Approach for the Determination of Gatifloxacin Content in Eye Drops using a Carbon Paste Electrode Modified with Bismuth Vanadate

Objective To study the clinical efficacy of gatifloxacin eye drops for bacterial conjunctivitis.Methods A total of 240 cases that diagnosed as bacterial conjunctivitis were randomly divided into test group (gatifloxacin) and control group (floxacin).A random double-blind and paralled study was conducted on 120 cases with gatifloxacin and floxacin eye drops for bacterial conjunctivitis.The drug delivery into conjunctival sac was performed at 7-14 days (one-two drops per time, five times per day).Results Sixty-seven clinical common pathogenic bacteria were separated from the study.The antibacterial activity of gatifloxacin,floxacin, levofloxacin, ciprofloxacin was 98.51%, 85.07%, 95.52%, and 78.79% respectively.The antibacterial activity of gatifloxacin was the highest, and the statistic difference between gatifloxacin and floxacin was found.The effect of gatifloxacin eye drops was not worse than floxacin eye drops.Conclusions The gatifloxacin eye drops has characteristics with broad spectrum, powerfull antibacterial activity.The linical effect of gatifloxacin eye drops is the same with floxacin eye drops.Gatifloxacin eye drops are safe and can be used to treat bacterial conjunctivitis.It has comparatively theropic value of ocular surface disease with Gram-positive bacterial and Gram-negetive bacterial. Key words: Gatifloxacin eye drops; Bacterial conjunctivitis; Antibacterial activity

Cyclic voltammetry and differential pulse voltammetry were used to explore the adsorption behavior of three antibacterial agents at a carbon paste electrode. The drugs were accumulated on a carbon paste electrode, and a well-defined oxidation peak was obtained in acetate buffer (pH 5.0). The adsorptive stripping response was evaluated as a function of some variables such as the scan rate, pH and accumulation time. A simple, precise, inexpensive and sensitive voltammetric method has been developed for the determination of the cited drugs (Lomefloxacin (LFX), Sparfloxacin hydrochloride (SFX), and Gatifloxacin (GFX)). A linear calibration was obtained from 2 x 10(-7) M to 4 x 10(-5) M for LFX, 2 x 10(-7) M to 6 x 10(-5) M for SFX, and GFX. The limits of detection (LOD) were 4.2 x 10(-7), 7 x 10(-7) and 6.6 x 10(-7) M, while the limits of quantification (LOQ) were 1.4 x 10(-6), 2.3 x 10(-6) and 2.2 x 10(-6) M for LFX, SFX, and GFX, respectively. The R. S. D. of five measurements at the 1 x 10(-6) M level were 0.4, 0.5 and 0.3 for LFX, SFX and GFX, respectively. The method was applied to the determination of LFX, SFX and GFX in dilute urine samples and dosage forms, and compared with the HPLC method.

The In vitro Impact of Moxifloxacin and Gatifloxacin Concentration (0.5% vs 0.3%) and the Addition of Benzalkonium Chloride on Antibacterial Efficacy

A voltammetric determination of ofloxacin (OF), norfloxacin (NF), gatifloxacin (GF), and lomefloxacin (LF) at a β-cyclodextrin-modified carbon-paste electrode (CDMCPE) is described. A large increase in the peak currents was observed in cyclic voltammetry (CV) and differential pulse voltammetry (DPV) of OF, NF, GF, and LF at CDMCPE compared with a bare carbon-paste electrode (CPE). These increases in the peak currents were attributed to the complex formation of the quinone group of the drugs with β-cyclodextrin. CV studies indicate that the process is irreversible and adsorption-controlled. The experimental parameters which influence the peak current responses of OF, NF, GF, and LF were studied. The reduction peak currents of OF, NF, GF, and LF change linearly over the common concentration range from 3.2 × 10−8 to 2 × 10−5 M, with a common correlation coefficient and limit of detection of 0.9995 and 2.4 × 10−8 M, respectively, in pH 4.0 Britton-Robinson (BR) buffer at an accumulation time of 160 s. The interference of metal ions in the peak current response was also studied. The modified electrode exhibited good sensitivity and stability. The proposed method was applied to the determination of OF, NF, GF, and LF in both commercially available drugs and spiked human urine samples.

The authors topically administered gatifloxacin (GFLX) into the eye before cataract surgery and measured the concentrations of this agent to determine its penetration into aqueous humor. Seventy-seven patients with age-related cataracts who underwent cataract surgery were enrolled in this study. They received 0.3% GFLX ophthalmic solution 4 times at 30-min intervals, beginning 2 h before surgery. Aqueous humor was aspirated from the anterior chamber and assayed for GFLX concentration using high-performance liquid chromatography. The mean intraoperative GFLX concentration in aqueous humor was 0.485 ± 0.328 μ g/mL. GFLX level was 0.573 ± 0.367 μ g/mL in elderly patients, at least 70 years of age, and was significantly higher than that (0.322 ± 0.135 μ g/mL) in the patients less than 70 years old. This concentration was close to or higher than the minimum inhibitory concentrations required to inhibit the growth of 90% of major pathogens of endophthalmitis (MIC90), such as Staphylococcus aureus, Streptococcus pneumoniae, and Enterococcus faecalis associated with poor prognosis, other than Staphylococcus epidermidis, Pseudomonas aeruginosa, and MRSA (methicillin-resistant S. aureus) in vitro. The GFLX concentrations found in aqueous humor samples were sufficient to kill bacteria other than S. epidermidis, P. aeruginosa, and MRSA in vitro.

A novel molecularly imprinted sensing platform based on MWCNTs/AuNPs decorated 3D starfish like hollow nickel skeleton as a highly conductive nanocomposite for selective and ultrasensitive analysis of a novel pan-genotypic inhibitor velpatasvir in body fluids

Shotgun metagenomics sequencing is a powerful tool for the characterization of complex biological matrices, enabling analysis of prokaryotic and eukaryotic organisms in a single experiment, with the possibility of de novo reconstruction of the whole metagenome or a set of genes of interest. One of the main factors limiting the use of shotgun metagenomics on wide scale projects is the high cost associated with the approach. However, we demonstrate that-for some applications-it is possible to use shallow shotgun metagenomics to characterize complex biological matrices while reducing costs. Here we compared the results obtained on full size, real datasets with results obtained by randomly extracting a fixed number of reads. The main statistics that were compared are alpha diversity estimates, species abundance, and ability of reconstructing the metagenome in terms of length and completeness. Our results show that a classification of the communities present in a complex matrix can be accurately performed even using very low number of reads. With samples of 100,000 reads, the alpha diversity estimates were in most cases comparable to those obtained with the full sample, and the estimation of the abundance of all the present species was in excellent agreement with those obtained with the full sample. On the contrary, any task involving the reconstruction of the metagenome performed poorly, even with the largest simulated subsample (1M reads). The length of the reconstructed assembly was sensibly smaller than the length obtained with the full dataset, and the proportion of conserved genes that were identified in the meta-genome was drastically reduced compared to the full sample. Shallow shotgun metagenomics can be a useful tool to describe the structure of complex matrices, but it is not adequate to reconstruct de novo-even partially-the metagenome.

Shotgun metagenomics sequencing is a powerful tool for the characterization of complex biological matrices, enabling analysis of prokaryotic and eukaryotic organisms and viruses in a single experiment, with the possibility of reconstructing de novo the whole metagenome or a set of genes of interest. One of the main factors limiting the use of shotgun metagenomics on wide scale projects is the high cost associated with the approach. However, we demonstrate that—for some applications—it is possible to use shallow shotgun metagenomics to characterize complex biological matrices while reducing costs. We measured the variation of several summary statistics simulating a decrease in sequencing depth by randomly subsampling a number of reads. The main statistics that were compared are alpha diversity estimates, species abundance, detection threshold, and ability of reconstructing the metagenome in terms of length and completeness. Our results show that a classification of prokaryotic, eukaryotic and viral communities can be accurately performed even using very low number of reads, both in mock communities and in real complex matrices. With samples of 100,000 reads, the alpha diversity estimates were in most cases comparable to those obtained with the full sample, and the estimation of the abundance of all the present species was in excellent agreement with those obtained with the full sample. On the contrary, any task involving the reconstruction of the metagenome performed poorly, even with the largest simulated subsample (1M reads). The length of the reconstructed assembly was smaller than the length obtained with the full dataset, and the proportion of conserved genes that were identified in the meta-genome was drastically reduced compared to the full sample. Shallow shotgun metagenomics can be a useful tool to describe the structure of complex matrices, but it is not adequate to reconstruct—even partially—the metagenome.

Paracetamol (PCT), or acetaminophen, is an important drug used worldwide for various clinical purposes. However, the excessive or indiscriminate use of PCT can provoke liver and kidney dysfunction; hence, it is essential to determine the amount of this target in biological samples. In this work, we develop a quick, simple, and sensitive voltammetric method using chemically modified electrodes to determine PCT in complex matrices, including human serum and commercial solid formulations. We modify the carbon paste electrode with stevensite monoclinic clay mineral (Stv-CPE), using cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy to characterise and detect PCT. The kinetics study provides a better electrochemical characterisation of the electrode behaviour, finding the detection and quantitation limits of 0.2 μM and 0.5 μM under favourable conditions. Further, the best linear working concentration range is 0.6-100 μM for PCT, applying the proposed method to the quantitative determination of PCT content in reference tablet formulations and biological samples for validation.

Melatonin (N‐acetyl‐5‐methoxytryptamine) is a neuroendocrine hormone produced in the pineal gland and distributed throughout the body. It has an important role in human physiology in synchronizing biological processes in neuroscience for regulating sleep and mood, and in clinical diagnosis for managing sleep disorders and exploring its therapeutics. However, melatonin recently received special attention because it has been proposed as an adjuvant in treating SARS‐CoV‐2 (severe acute respiratory syndrome coronavirus 2), the coronavirus responsible for the COVID‐19 pandemic. Therefore, the sensitive detection of melatonin in pharmaceutical samples and biological fluids (such as blood, saliva, breast milk, and urine) is important to ensure proper dosage or optimize treatment and to determine endogenous levels, even in pharmacological research and safety. In that sense, this review focuses on the recent development of electrochemical sensors for melatonin, emphasizing the use of modified electrodes to enhance sensitivity and selectivity. Different electrode materials, including screen‐printed carbon (SPE), glassy carbon (GC), boron‐doped diamond (BDD), and carbon paste electrodes (CPE), are explored for their effectiveness in melatonin detection. Additionally, the application of voltammetric techniques, such as differential pulse voltammetry (DPV) and square wave voltammetry (SWV) is highlighted for their ability to provide high‐resolution detection with minimal interference. Other electrochemical techniques, including cyclic voltammetry (CV) and chronoamperometry (CA), are also discussed in their role for melatonin sensing. These electrochemical techniques provide significant benefits, such as fast, sensitive, and affordable detection, making them essential tools in pharmaceuticals, clinical diagnostics, and biological research. On the other hand, this article explores the detection of synthetic melatonin, both individually and in the presence of interfering substances, such as serotonin, dopamine, and acetaminophen, with a focus on the challenges and techniques for distinguishing melatonin from other compounds in complex biological matrices, such as urine, blood, saliva, and pharmaceutical tablets.

This study aimed to develop and apply a novel zeolite-modified electrode (ZME), integrating Cu-exchanged zeolite Y (Cu-ZY) with a conductive carbon matrix composed of multi-walled carbon nanotubes (MWCNTs), for the sensitive and selective voltammetric determination of agomelatine (AGO), an important antidepressant, the accurate determination of which in pharmaceutical and biological samples is critical for therapeutic monitoring and quality control. Drop-casting the Cu-ZY/MWCNTs composite onto the surface of a glassy carbon electrode (GCE) resulted in the formation of a unique sensing platform, which exhibited a significantly improved electrochemical response for the oxidation of AGO. The enhanced activity of Cu-ZY/MWCNTs-GCE, attributed to the synergistic combination of Cu-ZY and MWCNTs, was confirmed by morphological, textural, and voltammetric analyses. Differential pulse voltammetry (DPV) was utilized for the quantitative determination of AGO, with optimization performed on instrumental parameters, supporting electrolyte pH, and preconcentration time (tacc). Using the Britton–Robinson buffer (BRB) solution at pH 3.0, the Cu-ZY/MWCNTs-GCE exhibited a linear response to AGO concentrations ranging from 8.2 × 10−9–9.6 × 10−7 mol L−1 (0.002–0.23 mg L−1), achieving a detection limit (LOD) of 4.3 × 10−9 mol L−1 (1.04 µg L−1) with a preconcentration time of 60 s. The successful determination of AGO in pharmaceutical formulations, wastewater, and biological fluids, with recoveries ranging from 98.0 to 113.0%, demonstrates the effectiveness and practical applicability of the Cu-ZY/MWCNT-GCE-based voltammetric method for agomelatine analysis in complex matrices.

Background Infectious keratitis is common blinding eye disease in China. Inflammatory runaway reaction often occurs in infectious keratitis, and its mechanism and treating approach are worthy of research. Objective This study was to investigate the clinical manifestation, mechanism and treatment outcome of doxycycline in overwhelming inflammation induced by Pseudomonas aeruginosa keratitis. Methods Pseudomonas aeruginosa suspension was intrastromal injected in 60 right eyes of 60 New Zealand white rabbits, and gatifloxacin eye drops was frequent instilled for consecutive 3 days to establish corneal inflammatory runaway reaction models, and 42 eyes with worse keratitis were defined as overwhelming inflammation. Then the models were randomly divided into gatifloxacin treatment group (15 rabbits), combined treatment group (gatifloxacin with doxycycline treatment, 15 rabbits) and balance salt solution (BSS) control group (12 rabbits), and corresponding eye drops was topically administered in the rabbits 8 times per day for 14 days. The symptoms of the models were observed under the slit lamp microscope on day 1, 3, 7 and 14 after treatment, and the corneal infiltration area was calculated. The corneal morphology was examined by using hematoxylin-eosin staining. The expressions of matrix metalloproteinase-2 (MMP-2) and MMP-9 in the corneal tissue were examined by immunohistochemistry. The contents of tumor necrosis factor α (TNF-α) and interleukin-1β (IL-1β) in corneal homogenate were detected by ELISA. The use and care of the animals complied with the ARVO Statement. Results The inflammatory scores were lower and infiltration area of cornea was smaller 7 days after treatment than those before treatment in the combined treatment group and gatifloxacin treatment group (both at P<0.05). Hematoxylin-eosin staining result showed that the inflammation response of cornea subsided 14 days in comparison with 5 days after treatment in the combined treatment group, with the proliferation and rearrangement of fiberal tissue. The MMP-2 and MMP-9 were strongly expressed in corneal tissue with overwhelming inflammation in day 5 after treatment, however, the expression intensity weakened in 14 days after treatment in the combined treatment, showing significant differences in the absorbance between them (all at P<0.05). ELISA assay showed that the contents of TNF-α and IL-1β in corneal tissue were significantly lower in the combined treatment group than those in the BSS group (P=0.00, 0.03). In addition, contents of TNF-α and IL-1β in corneal tissue were significantly declined at day 14 in comparison with day 5 and day 7 after treatment in the combined treatment group (all at P<0.05). Conclusions Overwhelming inflammatory keratitis models can be successfully established by corneal intrastromal injection of Pseudomonas aeruginosa suspension and immediately frequent 3-day instillation of gatifloxacin eye drops in rabbits. The topical application of doxycycline plays treating effect on overwhelming inflammatory keratitis by inhibiting the release of pro-inflammatory cytokines and MMPs. Key words: [Key words] Infectious eye disease, corneal; Bacteria; Pseudomonas aeruginosa; Antibacterial agents; Overwhelming inflammation; Keratitis/drug therapy; Doxycycline; Disease models, animal; Rabbits

Monitoring the acetaminophen in biological samples and also in pharmaceutical formulations is important due to the concerns of public health care and drug safety. In this work a carbon paste electrode modified with BaTiO3 nanoparticle (BTO NPs) and room-temperature ionic liquid (IL) (n-hexyl-3-methylimidazolium hexafluoro phosphate) was fabricated. The direct electro-oxidation behavior of acetaminophen (AC) was carefully studied by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and chronoamperometry (CHA) and the diffusion coefficient, D of acetaminophen at the BTOILCPE surface was estimated. The results exhibited remarkable increase in the electron transfer rate and significant decrease in the overpotential for acetaminophen oxidation reaction in contrast to that on the bare carbon paste electrode (CPE). Under the optimal conditions, using DPV the oxidation peak current was linear to the acetaminophen concentration over the range of 1.0 to 600.0 μM with a detection limit of 0.46 μM. The proposed sensor was successfully applied in pharmaceutical and urine samples with satisfactory results.

Nucleic acid probes in living organisms play an essential role in therapeutics and diagnosis. Through the imaging and sensing of nucleic acid probes in complex biological matrices, a variety of diseases-related biological process, pathogenic process, or pharmacological responses to a therapeutic intervention have been discovered. However, a critical challenge of nucleic acid probes applied in complex matrices lies in enhancing the stability of nucleic acid probes, especially when it suffers from nuclease degradation and protein adsorption. In order to enhance the application of nucleic acid nanoprobes in complex matrices, great efforts have been devoted to improving the stability of probes operated in complex media, including construction of nucleic acid nanoprobes with nuclease resistance and protein adsorption resistance, sample pretreatment, anti-biofouling and signal correction. In this review, we aim to summarize recent advances in the stability of nucleic acid nanoprobes in complex matrices, including the methods of enhancing the stability of probes or signals, and the application of nucleic acid nanoprobes for disease diagnosis.

Quantifying and monitoring the level of N-acylethanolamines (NAEs) in biological fluids is becoming increasingly important to better understand their role in health and disease. The complexity of biological matrices, however, poses significant challenges for accurate quantification, with traditional pretreatment methods often proving insufficient in certain cases. This study introduces a novel approach utilizing Online Solid Phase Extraction (SPE) to quantify NAEs in equine plasma, specifically Palmitoyl Ethanolamide (PEA) and Oleoyl Ethanolamide (OEA). In the original analytical method here developed and validated, established toluene liquid-liquid extraction was used to isolate the lipid-like fraction, followed by an innovative Time-Controlled Online SPE coupled to HPLC-MS/MS. This strategic temporal approach allows target analytes to rapidly elute to the analytical column while retaining lipidic interferents, preventing matrix contamination and ensuring selective analysis. The method validation demonstrated excellent linearity, while providing high recovery and suitable matrix effects. The limits of detection (LOD) and quantification (LOQ) were determined as 0.27 ng/mL and 0.83 ng/mL for PEA; 0.04 ng/mL and 0.11 ng/mL for OEA. The innovative approach here presented allowed for reliable NAE quantification in equine plasma and provided unprecedented data on the endogenous levels of PEA and OEA in this species. This method has potential applications for the analysis of other complex biological matrices with high levels of interferents that share chemical similarities with the target compounds. This novel approach significantly advances the understanding of the endocannabinoid system in equines and serves as a valuable tool for future research in this domain.