Drug Tetracycline Hydrochloride Research Articles

Enhanced Fenton Degradation of Tetracycline over Cerium-Doped MIL88-A/g-C3N4: Catalytic Performance and Mechanism.

Since enormous amounts of antibiotics are consumed daily by millions of patients all over the world, tons of pharmaceutical residuals reach aquatic bodies. Accordingly, our study adopted the Fenton catalytic degradation approach to conquer such detrimental pollutants. (Ce0.33Fe) MIL-88A was fabricated by the hydrothermal method; then, it was supported on the surface of g-C3N4 sheets using the post-synthetic approach to yield a heterogeneous Fenton-like (Ce0.33Fe) MIL-88A/10%g-C3N4 catalyst for degrading the tetracycline hydrochloride drug. The physicochemical characteristics of the catalyst were analyzed using FT-IR, SEM-EDX, XRD, BET, SEM, and XPS. The pH level, the H2O2 concentration, the reaction temperature, the catalyst dose, and the initial TC concentration were all examined as influencing factors of TC degradation efficiency. Approximately 92.44% of the TC was degraded within 100 min under optimal conditions: pH = 7, catalyst dosage = 0.01 g, H2O2 concentration = 100 mg/L, temperature = 25 °C, and TC concentration = 50 mg/L. It is noteworthy that the practical outcomes revealed how the Fenton-like process and adsorption work together. The degradation data were well-inspected by first-order and second-order models to define the reaction rate. The synergistic interaction between the (Ce0.33Fe) MIL-88A/10%g-C3N4 components produces a continuous redox cycle of two active metal species and the electron-rich source of g-C3N4. The quenching test demonstrates that •OH is the primary active species for degrading TC in the H2O2-(Ce0.33Fe) MIL-88A/10%g-C3N4 system. The GC-MS spectrum elucidates the yielded intermediates from degrading the TC molecules.

Profiling of Modified Chitosan-Based Composites as Tetracycline Hydrochloride Drug Release Systems

Profiling of Modified Chitosan-Based Composites as Tetracycline Hydrochloride Drug Release Systems

Nanofiber-reinforced self-healing polysaccharide-based hydrogel dressings for pH discoloration monitoring and treatment of infected wounds

The escalating global health concern arises from chronic wounds induced by bacterial infections, posing a significant threat to individuals. Consequently, an imperative exist for the development of hydrogel dressings to facilitate prompt wound monitoring and efficacious wound management. To this end, pH-sensitive bromothymol blue (BTB) and pH-responsive drug tetracycline hydrochloride (TH) were introduced into the polysaccharide-based hydrogel to realize the integration of wound monitoring and controlled treatment. Polysaccharide-based hydrogels were formed via a Schiff base reaction by cross-linking carboxymethyl chitosan (CMCS) on an oxidized sodium alginate (OSA) skeleton. BTB was used as a pH indicator to monitor wound infection through visual color changes visually. TH could be dynamically released through the pH response of the Schiff base bond to provide effective treatment and long-term antibacterial activity for chronically infected wounds. In addition, introducing polylactic acid nanofibers (PLA) enhanced the mechanical properties of hydrogels. The multifunctional hydrogel has excellent mechanical, self-healing, injectable, antibacterial properties and biocompatibility. Furthermore, the multifaceted hydrogel dressing under consideration exhibits noteworthy capabilities in fostering the healing process of chronically infected wounds. Consequently, the research contributes novel perspectives towards the advancement of intelligent and expeditious bacterial infection monitoring and dynamic treatment platforms.

Synergistic integration of ZrO2-enriched reduced graphene oxide-based nanostructures for advanced photodegradation of tetracycline hydrochloride.

The escalating demand for the antibiotic drug tetracycline hydrochloride (TCH) contributes to an increased release of its residues into land and water bodies, which poses risks to both aquatic life and human health. Therefore, it is precedence to effectively degrade TCH residues to protect environment from their long-term impacts. In this aspect, the present study entails the synthesis of zirconia (ZrO2) nanostructures and focuses on the enhancement in the catalytic performance of ZrO2 nanostructures by employing reduced graphene oxide (RGO) as a solid support to synthesize ZrO2-enriched RGO-based photocatalysts (ZrO2-RGO) for the degradation of TCH. The study delves into comprehensive spectroscopic and microscopic investigations and their photodegradation assessments. Powder XRD and HR-TEM studies depicted the phase crystallinity and also displayed uniform distribution of ZrO2 nanostructures with spherical morphology within ZrO2-RGO. This corresponds to high surface-to-volume ratios, providing a substantial number of active sites for light absorption and generation of e--h+ pairs. Moreover, the heterojunctions created between RGO and ZrO2 nanostructures promoted the interspecies electron transfer which prolonged the recombination time of e- and h+ than pure ZrO2 nanostructures, accounted for enhanced degradation of TCH using ZrO2-RGO. The photocatalytic activity of as-synthesized materials were examined under visible and UV light irradiation.Thedegradation efficiency of ~ 73.82% was achieved using ZrO2-RGO-based photocatalystwith rate constant k = 0.007023 min-1 under visible-light illumination.Moreover, under UV-light, the degradation rate was explicated to be k = 0.01017 min-1 with ~ 85.56% degradation of TCH antibiotics within 180 mins. Hence, the synthesized ZrO2-enriched RGO-based photocatalysts represents a promising potential for the effective degradation of pharmaceutical compounds, particularly TCH under visible and UV-light irradiation.

Multifunctional Double-Layer and Dual Drug-Loaded Microneedle Patch Promotes Diabetic Wound Healing.

Chronic nonhealing diabetic wounds are a serious complication of diabetes, with a high morbidity rate that can cause disability or death. The long period of inflammation and dysfunctional angiogenesis are the main reasons for wound-healing difficulty in diabetes. In this study, a multifunctional double-layer microneedle (DMN) is constructed to control infection and promote angiogenesis, meeting the multiple demands of the healing process of a diabetic wound. The double-layer microneedle is consisted in a hyaluronic acid substrate and a mixture of carboxymethyl chitosan and gelatin as the tip. The antibacterial drug tetracycline hydrochloride (TH) is loaded into the substrate of the microneedle to achieve rapid sterilization and promote resistance to external bacterial infections. The microneedle tip loaded with recombinant human epidermal growth factor (rh-EGF) is inserted into the skin, in response to gelatinase produced by resident microbe and disassociate to achieve the enzymatic response release. The double-layer drug-loaded microneedles (DMN@TH/rh-EGF) have antibacterial and antioxidant effects, and promote cell migration and angiogenesis in vitro. In an in vivo diabetic wound model, using rats, the DMN@TH/rh-EGF patch is able to inhibit inflammation, promote angiogenesis, collagen deposition, and tissue regeneration during the wound healing process, promoting its healing.

Insights into Drug-Loading Capacity of Bio-Zirconium Metal-Organic Frameworks Nanoparticles for Tetracycline Hydrochloride

The discovery of a highly efficient drug delivery system with high biocompatibility and good loading/release properties is a key challenging issue. In the past decade, metal-organic frameworks (MOFs) have shown great interest as drug delivery systems (DDSs), due to their high porosity, tunable functionality, and large drug loading capacities. Herein, we report the potential use of a new family of biocompatible MOFs called bio-MOFs synthesized from bio-based ligands and water-based synthesis for drug delivery. We propose a facile method to synthesize MIP-202 (bio-based Zr-MOF) built from Zr metal nodes and aspartic acid as an amino acid ligand. The efficiency of loading tetracycline hydrochloride drug onto MIP-202 and UiO-66-NH2 has been carefully studied. Characterization techniques such as powder X-ray diffraction, and transmission electron microscopy have been used for structural and morphological confirmation. The loading capacity of tetracycline hydrochloride on UiO-66-NH2 was determined to be higher than MIP-202 reaching up to 50.3%. The results provide an investigated insight into the utilization of bio-based MOFs as drug carriers for tetracycline hydrochloride.

The release kinetic of drug encapsulated poly(L-lactide-co-ɛ-caprolactone) core-shell nanofibers fabricated by emulsion electrospinning

Core-shell nanofibers for biomedical applications have been successfully prepared by emulsion electrospinning, utilizing the model drug Tetracycline hydrochloride (TCH) water solution as the “aqueous phase” and hydrophobic polymer solution as the “organic phase.” The morphology of nanofibers was assessed by scanning electron microscopy (SEM) and the core-shell structure was confirmed by inverted fluorescence microscopy and transmission electron microscopy (TEM). The improved hydrophilicity might be caused by the presence of the emulsifier Span 80 on the surface of the nanofibers. The mechanical properties study showed that core-shell nanofibers membranes were softer and more elastic than blended nanofibers. In vitro drug release study showed that the TCH could release continuously for 34 days. The release mechanism of the nanofibers followed Fickian diffusion at low drug efficiency, but drug diffusion was the best fit with the First-order kinetic model when increasing drug loading rates. Overall, emulsion core-shell nanofibers could be used as a promising drug reservoir for sustained and continuous drug release behaviors. Meanwhile, the study of drug release kinetics was used in conjunction with model drug properties to develop a wider range of nanofibers carriers and biomaterials.

Zein-polycaprolactone core–shell nanofibers for wound healing

In a previous study, we developed electrospun antimicrobial microfiber scaffolds for wound healing composed of a core of zein protein and a shell containing polyethylene oxide. While providing a promising platform for composite nanofiber design, the scaffolds showed low tensile strengths, insufficient water stability, as well as burst release of the antimicrobial drug tetracycline hydrochloride, properties which are not ideal for the use of the scaffolds as wound dressings. Therefore, the aim of the present study was to develop fibers with enhanced mechanical strength and water stability, also displaying sustained release of tetracycline hydrochloride. Zein was chosen as core material, while the shell was formed by the hydrophobic polymer polycaprolactone, either alone or in combination with polyethylene oxide. As compared to control fibers of pristine polycaprolactone, the zein-polycaprolactone fibers exhibited a reduced diameter and hydrophobicity, which is beneficial for cell attachment and wound closure. Such fibers also demonstrated sustained release of tetracycline hydrochloride, as well as water stability, ductility, high mechanical strength and fibroblast attachment, hence representing a step towards the development of biodegradable wound dressings with prolonged drug release, which can be left on the wound for a longer time.

Vanadium(IV) coordination complexes with excellent biological activities: a synthetic, characterization, and density functional theory approach

A set of new oxidovanadium(IV) complexes, [VO(4-NO2C6H4CH = CHCONHO)2] (1), [VO(4-NO2C6H4CH = CHCONHO)2(2–CNC5H4N)] (2) and [VO(4-NO2C6H4CH = CHCONHO)2(4-CNC6H4NH2)] (3), have been synthesized and characterized by different analytical techniques (magnetic susceptibility, molar conductivity, elemental analysis) and spectroscopic techniques, viz. FTIR, UV–vis, EPR, and mass spectrometry. The magnetic susceptibility, EPR, and ESI-MS data indicate that 1 exists as monomer and a distorted square pyramidal geometry around vanadium is ascertained. The electrochemical study of 1 has shown that it is electrochemically active exhibiting VOV/VOIV quasi-reversible redox couple. The biological activity of 1–3 has been studied against various pathogenic bacteria Staphylococcus epidermidis, Klebsiella pneumoniae, Staphylococcus aureus, Escherichia coli, Salmonella paratyphi, and Salmonella typhi, and fungi Brachypsectra fulva, Candida albicans, and Fusarium oxysporum by minimum inhibitory concentration (MIC) method. In some cases, the synthesized complexes showed superior antibacterial and antifungal activity than the well-known standard drugs tetracycline hydrochloride and fluconazole. The cytotoxicity of 1–3 has been studied on a human cervix carcinoma HeLa cell derivative (mammalian transformed cell line Hep2c) by MTT assay. Density functional theory (DFT) studies have been carried out to determine their relative free energy of formation and optimized molecular structures of 1–3. Time-dependent density functional theory (TD-DFT) based calculations have been performed to find out the frontier molecular orbitals and corroborate with the experimentally observed electronic transitions of 1. Other parameters like HOMO, LUMO energies, and global reactivity descriptors clearly support higher biological activity of 2 and 3 than 1.

Morphological Structures and Drug Release Effect of Multiple Electrospun Nanofibre Membrane Systems Based on PLA, PCL, and PCL/Magnetic Nanoparticle Composites

Biopolymers are good carrier materials in relation to efficient release sustainability for encapsulated drugs. In particular, electrospun polymer/composite fibre membranes can offer greater benefits owing to their competitive release features as well as large specific surface areas. In this study, multiple electrospun nanofibre membrane systems were utilised including different material systems such as poly(lactic acid) (PLA), poly(ε‐caprolactone) (PCL), and PCL/magnetic nanoparticle (MP) composites loaded with tetracycline hydrochloride (TCH) as a therapeutic compound for their potential use in drug delivery applications. Such electrospun nanofibres were investigated to understand how composite constituents could tailor surface morphology for drug release control and biodegradation effect of PCL electrospun nanofibers on a long term for different drug release systems. Fibre diameter appeared to be decreased considerably with the addition of TCH drug. It was also evident that average fibre diameter was reduced when embedding MPs owing to the enhancement of solution conductivity. The encapsulation of TCH drug was found to be effective, as evidenced by Fourier transform infrared (FTIR) spectra. Thermogravimetric analysis (TGA) data revealed no significant change in the thermal stability of PCL with the inclusion of TCH and MPs. However, the use of TCH to PLA delayed the thermal degradation. Glass transition temperature (Tg) and melting temperature (Tm) of PCL were decreased with the inclusion of MPs and TCH. The degree of crystallinity (Xc) for PCL diminished when incorporated with MPs. Additional TCH to PLA, PCL, and PCL/MP nanocomposites resulted in a moderate decrease in Xc. TCH might be dispersed in an amorphous state within nanofibre membranes. Over the short‐term periods, it was clearly seen that TCH release from PCL nanofibre membranes was higher as opposed to PLC/MP and PLA counterparts. On the contrary, such a drug release from PLC membranes became relatively slow owing to its high Xc. Further, the mass loss results were consistent with those obtained from in vitro drug release. Overall, TCH release kinetics of PCL/TCH nanofibre membranes were better estimated by Zeng model as opposed to PLA/TCH counterparts.

Improvement of Drug Release and Compatibility between Hydrophilic Drugs and Hydrophobic Nanofibrous Composites.

Electrospinning is a flexible polymer processing method to produce nanofibres, which can be applied in the biomedical field. The current study aims to develop new electrospun hybrid nanocomposite systems to benefit the sustained release of hydrophilic drugs with hydrophobic polymers. In particular, electrospun hybrid materials consisting of polylactic acid (PLA):poly(ε-caprolactone) (PCL) blends, as well as PLA:PCL/halloysite nanotubes-3-aminopropyltriethoxysilane (HNT-ASP) nanocomposites were developed in order to achieve sustained release of hydrophilic drug tetracycline hydrochloride (TCH) using hydrophobic PLA:PCL nanocomposite membranes as a drug carrier. The impact of interaction between two commonly used drugs, namely TCH and indomethacin (IMC) and PLA:PCL blends on the drug release was examined. The drug release kinetics by fitting the experimental release data with five mathematical models for drug delivery were clearly demonstrated. The average nanofiber diameters were found to be significantly reduced when increasing the TCH concentration due to increasing solution electrical conductivity in contrast to the presence of IMC. The addition of both TCH and IMC drugs to PLA:PCL blends reduced the crystallinity level, glass transition temperature (Tg) and melting temperature (Tm) of PCL within the blends. The decrease in drug release and the impairment elimination for the interaction between polymer blends and drugs was accomplished by mobilising TCH into HNT-ASP for their embedding effect into PLA:PCL nanofibres. The typical characteristic was clearly identified with excellent agreement between our experimental data obtained and Ritger–Peppas model and Zeng model in drug release kinetics. The biodegradation behaviour of nanofibre membranes indicated the effective incorporation of TCH onto HNT-ASP.

Cellulose nanofibrils composite hydrogel with polydopamine@zeolitic imidazolate framework-8 encapsulated in used as efficient vehicles for controlled drug release

Herein, we report a nanocellulose hydrogel that has a packaging structure for on-demand drug release. Zeolitic imidazolate frameworks-8 (ZIF-8) were grown on the surface of polydopamine (PDA) to produce PDA@ZIF-8 nanoparticles. The obtained PDA@ZIF-8 nanoparticles were then incorporated into a network of cellulose nanofibrils (CNFs) to fabricate a PDA@ZIF-8/CNFs composite hydrogel. The loading ratio of the drug tetracycline hydrochloride (TH) was 58%. A slight burst release behavior was observed at the beginning, and the composite hydrogel presented a significant pH-dependent release behavior. The drug delivery time of the PDA@ZIF-8/CNFs composite hydrogel was 3.5 times longer than that of the PDA/CNFs composite hydrogel. Furthermore, NIR light radiation accelerated the drug delivery rate. The drug release mechanism was mainly driven by anomalous transport. Importantly, the novel PDA@ZIF-8/CNFs composite hydrogel was found to be biocompatible according to in vitro cytotoxicity test. Because of its unique multiple drug release responses, the PDA@ZIF-8/CNFs composite hydrogel may be used in future clinical applications as a promising drug delivery carrier.

Antibactericidal nanoclay-based biomaterial for sustained delivery of tetracycline hydrochloride

Nanoclay-based drug delivery vehicle has acquired immense recognition owing to its unique physico-chemical properties. In this study, tetracycline hydrochloride (TCH) drug was intercalated into the interlayer gallery of montmorillonite (Mt) clay by a cation exchange process. The intercalated nanocomposites were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, energy dispersive X-ray and thermogravimetric study. It was evident from the characterization that TCH drug was successfully intercalated into the interlayer gallery of Mt clay. These clay-based formulations exhibited antibacterial activity against both Gram-positive and Gram-negative bacteria on analyses via zone inhibition methods. An in-vitro drug release study was performed in phosphate buffer at physiological temperature and interestingly it exhibited sustained and controlled release of TCH from the nanocomposites, after an initial burst-out effect. Overall, this study showed that these nanocomposite materials have immense potential for use in controlled drug delivery strategies for antibacterial treatment.

Controlled Hydration, Transition, and Drug Release Realized by Adjusting Layer Thickness in Alginate-Ca2+/poly(N-isopropylacrylamide) Interpenetrating Polymeric Network Hydrogels on Cotton Fabrics.

The controlled hydration, transition, and drug release are realized by adjusting layer thickness in thermoresponsive interpenetrating polymeric network (IPN) hydrogels on cotton fabrics. IPN hydrogels are synthesized by sodium alginate (SA) and poly(N-isopropylacrylamide) (PNIPAM) with a ratio of 1:5/% (w/v). The cotton-fabric-supported IPN hydrogels with a thickness of 1000 μm exhibit a transition temperature (TT) at 35.2 °C. When the hydrogel thicknesses are thinned to 500 and 250 μm, the TTs are reduced to 34.8 and 34.1 °C, respectively. Interestingly, the morphology of IPN hydrogels switches from a well-defined honeycomb-like network structure (1000 μm) to a densely packed layer structure (250 μm). The thinner layers not only present a smaller extent of hydration and collapse but also require longer time to reach an equilibrium state, which can be attributed to the more pronounced hindrance of the chain rearrangement by the cotton fabrics. To address the influence of layer thickness on the drug release, we compare the release rate and cumulative release percentage of the test drugs tetracycline hydrochloride (TCH) and levofloxacin hydrochloride (LH) between pure IPN hydrogels and cotton-fabric-supported IPN hydrogels (250, 500, and 1000 μm) at 25 °C (below the TT) and 37 °C (above the TT). Because of the compressive stress from the collapsed hydrogels, a higher release is observed in both hydrogels when the temperature is above TT. The cotton fabric induces a slower and less prominent drug release in IPN hydrogels. Thus, combining the obtained correlation between the transition and hydrogels layer thickness, the drug release in cotton-fabric-supported IPN hydrogels can be regulated by the layer thickness, which appears especially suitable for a controlled release in wound dressing applications.

Advanced nursing recovery therapy in the field of nanotechnology based on tetracycline hydrochloride type drugs

With the development of wound care theory and practice methods, the development of new materials and the improvement of sustained release and controlled release technologies, medical dressings will develop in the direction of multi-functionality, diversification and intelligence. This has also promoted the development of clinical care, better service for wound patients, new dressings, and new methods for wound care. Among many new dressings, nanotechnology-based polymer nanogels have good application prospects due to their good water retention properties and micelle stability properties. At present, a large number of researchers have developed a variety of wound care materials, which are widely used in clinical settings. However, due to the shape of the material or its characteristics, the mechanism of action of many materials has not been studied in detail. How to prepare a new type of wound dressing, which has multiple functions - integrating haemostasis, bacteriostatic, stimulating cell division and differentiation, accelerating tissue healing, moisturising and phlegm, etc., so as to achieve a good evaluation of patients' post-care recovery is. China's long-standing and urgent problem in the medical device market. Therefore, this study used the tetracycline hydrochloride drug doxycycline as an antibiotic drug for nano-modified dressings. Under the theoretical guidance of the interaction between wound healing and pH of microenvironment, a polyethylene glycol (PEG) modified PEG-doxycycline hydrogel nanocomposite dressing was prepared to study the stability of nanoparticles in the dressing. Physical and pH responsiveness, swelling behaviour of composite dressings, and physicochemical properties of drug release behaviour were studied. At the same time, in order to study the effect of the PEG-doxycycline nanocomposite hydrogel on the recovery of wound care in patients, this study applied the composite nano dressing to the clinic. Through the comparative study of patients' quality of life, wound healing, nursing satisfaction and treatment effect, the innovative application of tetracycline hydrochloride in the recovery of wound care of patients under nanotechnology is realised. The results of this study indicate that PEG-doxycycline nanocomposite hydrogel prepared under the guidance of nanotechnology can promote wound healing, shorten hospital stay and reduce complications. At the same time, the use of the dressing can also reduce the work of nursing, alleviate the suffering of the patient, improve the comfort of the patient, and greatly improve the nursing effect and effect on the patient. This has certain promotion and research value for the implementation of continuous nursing methods for patients with chronic wounds, which can be popularised in clinical practice.

Solid drug particles encapsulated bead-on-string nanofibers: the control of bead number and its corresponding release profile

Bead-on-string nanofibers are explored as potential carriers of micro-level solid drug particles in recent years in drug release and tissue engineering. The special alternating distribution of nanoscale fiber and micro beads satisfied the fully encapsulation of particle drugs and the corresponding sustained release. Antibiotic drug tetracycline hydrochloride (TCH) was used as solid model drug particles. The present study fabricated poly (lactic-co-glycolic acid) (PLG A) bead-on-string nanofibers with different TCH loading rates for the controlled drug delivery. Bead number (BN), as one of the crucial factors that determine the encapsulation capability, was successfully controlled by tailoring the electrospinning parameters: voltage, flow rate and distance. The in vitro release experiment analyze by UV-Visible light spectrophotometer indicated that the bead-on-string nanofiber with more BN would increase the total release quantity of TCH. The drug released from bead-on-string nanofibers was mainly driven by classical Fickian diffusion. PLGA bead-on-string nanofibers suggest the potential as promising substrate for solid drug particles delivery applications.

Fabrication of patterned three-dimensional micron scaled core-sheath architectures for drug patches

Recent advances in selective integration of micro and nano-scaled features towards material design have paved way to enhance desirable properties or functions of biomaterials. For drug delivery applications these include improved active component encapsulation, controlled drug release and managed interaction with the intended host environment. Electrohydrodynamic (EHD) direct-printing technique is a one-step on demand fiber deposition method which enables precise micron-scaled topographic and structural enhancement during material fabrication. In this study, core-sheath composite fibers comprising polycaprolactone, polyvinyl pyrrolidone and the drug tetracycline hydrochloride were prepared using the coaxial format of EHD direct-printing. Once positioned and aligned; multi-stacked fibers gave rise to patches. Coaxial fiber (diameter range ~13–25 μm) optimization (deposition and integrity) involved parameter-structure (e.g. collector speed, flow rate, working distance and applied voltage) impact analysis. Water contact angle measurements, tensile testing and Fourier transform infrared spectroscopy were used to analyze core-sheath integrated patches. In-vitro drug release studies clearly elude to the impact of core-shell and patterned architectures; demonstrating their viability and the forming method as emerging tools for advanced drug delivery system design and fabrication.

Fabrication and optimization of a sensitive tetracycline fluorescent nano-sensor based on oxidized starch polysaccharide biopolymer-capped CdTe/ZnS quantum dots: Box–Behnken design

A novel optical nano-sensor for tetracycline hydrochloride (TH) detection as a small molecule model was prepared by modifying the surface of CdTe/ZnS QDs with a biopolymer based cap, called poly ((2-dimethylaminoethyl) methacrylate) grafted onto oxidized starch (OS-g- PDMAEMA), via a facile method. The preparation of the nano-sensor was optimized by employing a 4-factor Box–Behnken statistical design to achieve a nano-sensor with maximum fluorescence intensity for sensitive determination of TH in real samples. The optimized nano-sensor based on CdTe/ZnS QDs were characterized by fluorescence spectroscopy, UV–vis spectrophotometry, transmission electron microscopy (TEM), Fourier transforms infrared (FTIR) and thermo-gravimetric (TG) analysis techniques. It was found that the fluorescence intensity of modified QDS (CdTe/ZnS-OS-g-PDMAEMA QDs) at 520 nm (excitation at 375 nm) was selectively quenched in the presence of trace amounts of TH drug. In this method, a simple, highly sensitive, selective and rapid analytical approach was used for the determination of TH in the concentration range of 9.14 × 10−9 mol L−1–7.23 × 10−6 mol L−1 with a detection limit of 2.74 × 10−9 mol L−1. The designed nano-sensor can be successfully applied for the determination of TH in complex matrixes (pharmaceutical formulations, urine, saline and glucose serums) with satisfactory analytical results.

Antenna effect and phosphorescence spectra to find the location of drug tetracycline in bovine β-lactoglobulin A

A ternary system comprising of a Eu(III) complex of the drug Tetracycline hydrochloride (Eu3TC) bound to bovine β-lactoglobulin variant A (BLGA) in aqueous buffer at physiological pH (pH = 7.4) has been investigated to exploit the enhanced "antenna effect" to locate the bound drug and find the microenvironment of the binding site. Steady-state and time-resolved emission studies at room temperature as well as at 77K have been carried out to evaluate the binding parameters in the binary system consisting of BLGA and tetracycline hydrochloride (TC). Low-temperature phosphorescence studies at 77K of pure BLGA confirm Trp 19 to be the emitting residue, while Trp 61 is silent. Enhancement of BLGA phosphorescence emission in the ternary system at 77K indicates that Trp 19 is very close to Eu(III) in the Eu3TC complex. The molecular docking results further confirm that TC binds close to Trp 19 in a hydrophobic domain. The results thus obtained can provide guidelines to design and synthesize target-oriented drugs as well as suitable bio-probes.

Porous Laponite/Poly(L-lactic acid) Membrane with Controlled Release of TCH and Efficient Antibacterial Performance

Fabrication of porous polymer membrane with controlled drug release and efficient antibacterial performances is of great interest in biomedical fields. In this study, Laponite (LAP) nanodisks were first used to encapsulate a model antibiotic drug, tetracycline hydrochloride (TCH). Then, drug-loaded LAP nanodisks with an optimized loading efficiency (85.3 %) were mixed with poly(L-lactic acid) (PLLA) polymer to form drug-loaded composite porous membrane via solvent coasting. The structure, morphology and swelling property of the porous membranes formed with varied solvent ratio of methylene dichloride (DCM) and dimethyl formamide (DMF) in the mixture solvent were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy and swelling test. In vitro drug release behavior, the cytotoxicity and the antibacterial activity of drug-loaded composite membranes were evaluated. Results showed that the TCH release was dependent on the physical structure of PLLA membrane and the presence of LAP nanodisks effectively weakened the initial burst release of TCH, and improved the sustained release property of porous PLLA membrane. The released TCH of TCH/LAP/PLLA3:1 and TCH/LAP/PLLA4:1 was 10.0 % and 5.3 % within initial 1 h, respectively. More importantly, the porous TCH/LAP/PLLA membrane was cytocompatible and displayed considerable antibacterial activity, solely associated with the loaded TCH drug, confirming its potential utility in wound dressings and tissue engineering.