Encapsulation of zinc-rifampicin complex into transferrin-conjugated silver quantum-dots improves its antimycobacterial activity and stability and facilitates drug delivery into macrophages

Quantum Dot-Based Nanosensors for In Vitro Detection of Mycobacterium tuberculosis

Despite the existing effective treatment methods, tuberculosis (TB) is the second most deadly infectious disease, its carriers in the latent and active phases accounting for more than 20% of the world population. An effective method for controlling TB and reducing TB mortality is regular population screening aimed at diagnosing the latent form of TB and taking preventive and curative measures. Numerous methods allow diagnosing TB by directly detecting Mycobacterium tuberculosis (M.tb) biomarkers, including M.tb DNA, proteins, and specific metabolites or antibodies produced by the host immune system in response to M.tb. PCR, ELISA, immunofluorescence and immunochemical analyses, flow cytometry, and other methods allow the detection of M.tb biomarkers or the host immune response to M.tb by recording the optical signal from fluorescent or colorimetric dyes that are components of the diagnostic systems. Current research in biosensors is aimed at increasing the sensitivity of detection, a promising approach being the use of fluorescent quantum dots as brighter and more photostable optical tags. Here, we review current methods for the detection of M.tb biomarkers using quantum dot-based nanosensors and summarize data on the M.tb biomarkers whose detection can be made considerably more sensitive by using these sensors.

Design, synthesis and antimycobacterial activity of imidazo[1,5-a]quinolines and their zinc-complexes

Tuberculosis has remained one of the world's deadliest infectious diseases. The complexity and numerous adverse effects of current treatment options as well as the emergence of multi-drug resistant M. tuberculosis (Mtb) demand research and innovation efforts to yield new anti-mycobacterial agents. In this study, we synthesized a series of imidazo[1,5-a]quinolines, including 4 new analogs, and evaluated their activity against Mtb. Inspired by previous studies, we also designed 8 compounds featuring a coordinated metal ion, determined their absolute configuration by single-crystal X-ray diffraction and included them in the bioactivity study. Remarkably, the metal complexation of 5c with either Zn2+ or Fe2+ increased the Mtb inhibitory activity of the compound 12.5-fold and reduced its cytotoxicity. Ultimately, out of the 21 analyzed imidazo[1,5-a]quinoline analogs, two zinc complexes (C1 and C7) showed the strongest, specific activity against Mtb H37Rv in vitro (IC90 = 7.7 and 17.7 μM).

Essential considerations towards development of effective nasal antibiotic formulation: features, strategies, and future directions

INTRODUCTION

Intranasal antibiotic products are gaining popularity as a promising method of administering antibiotics, which provide numerous benefits, e.g. enhancing drug bioavailability, reducing adverse effects, and potentially minimizing resistance threats. However, some issues related to the antibiotic substances and nasal route challenges must be addressed to prepare effective formulations.

AREAS COVERED

This review focuses on the valuable points of nasal delivery as an alternative route for administering antibiotics, coupled with the challenges in the nasal cavity that might affect the formulations. Moreover, this review also highlights the application of nasal delivery to introduce antibiotics for local therapy, brain targeting, and systemic effects that have been conducted. In addition, this viewpoint provides strategies to maintain antibiotic stability and several crucial aspects to be considered for enabling effective nasal formulation.

EXPERT OPINION

In-depth knowledge and understanding regarding various key considerations with respect to the antibiotic substances and nasal route delivery requirement in preparing effective nasal antibiotic formulation would greatly improve the development of nasally administered antibiotic products, enabling better therapeutic outcomes of antibiotic treatment and establishing appropriate use of antibiotics, which in turn might reduce the chance of antibiotic resistance and enhance patient comfort.

Nano vs Resistant Tuberculosis: Taking the Lung Route

Tuberculosis (TB) is among the top 10 infectious diseases worldwide. It is categorized among the leading killer diseases that are the reason for the death of millions of people globally. Although a standardized treatment regimen is available, non-adherence to treatment has increased multi-drug resistance (MDR) and extensive drug-resistant (XDR) TB development. Another challenge is targeting the death of TB reservoirs in the alveoli via conventional treatment. TB Drug resistance may emerge as a futuristic restraint of TB with the scarcity of effective Anti-tubercular drugs. The paradigm change towards nano-targeted drug delivery systems is mostly due to the absence of effective therapy and increased TB infection recurrent episodes with MDR. The emerging field of nanotechnology gave an admirable opportunity to combat MDR and XDR via accurate diagnosis with effective treatment. The new strategies targeting the lung via the pulmonary route may overcome the new incidence of MDR and enhance patient compliance. Therefore, this review highlights the importance and recent research on pulmonary drug delivery with nanotechnology along with prevalence, the need for the development of nanotechnology, beneficial aspects of nanomedicine, safety concerns of nanocarriers, and clinical studies.

Exploring the antimicrobial potential of isoniazid loaded Cu-based metal-organic frameworks as a novel strategy for effective killing of Mycobacterium tuberculosis

Tuberculosis (TB) remains one of the most infectious pathogens with the highest human mortality and morbidity. Biofilm formation during Mycobacterium tuberculosis (Mtb) infection is responsible for bacterial growth, communication, and, most essentially, increased resistance/tolerance to antibiotics leading to higher bacterial persistence. Thus, biofilm growth is presently considered a key virulence factor in the case of chronic disease. Metal-Organic Frameworks (MOFs) have recently emerged as a highly efficient system to improve existing antibiotics' therapeutic efficacy and reduce adverse effects. In this regard, we have synthesized Cu-MOF (IITI-3) using a solvothermal approach. IITI-3 was well characterized by various spectroscopic techniques. Herein, IITI-3 was first encapsulated with isoniazid (INH) to form INH@IITI-3 with 10 wt% loading within 1 hour. INH@IITI-3 was well characterized by PXRD, TGA, FTIR, and BET surface area analysis. Furthermore, the drug release kinetics studies of INH@IITI-3 have been performed at pH 5.8 and 7.4 to mimic the small intestine and blood pH, respectively. The results show that drug release follows first-order kinetics. Furthermore, the antimycobacterial activity of INH@IITI-3 demonstrated significant bacterial killing and altered the structural morphology of the bacteria. Moreover, INH@IITI-3 was able to inhibit the mycobacterial biofilm formation upon treatment and showed less cytotoxicity toward the murine RAW264.7 macrophages. Thus, this work significantly opens up new possibilities for the applications of INH@IITI-3 in biofilm infections in Mtb and further contributes to TB therapeutics.

Targeted intracellular delivery of antitubercular bioactive(s) to Mtb infected macrophages via transferrin functionalized nanoliposomes

The packaging of antimicrobials/chemotherapeutics into nanoliposomes can enhance their activity while minimizing toxicity. However, their use is still limited owing to inefficient/inadequate loading strategies. Several bioactive(s) which are non ionizable, and poorly aqueous soluble cannot be easily encapsulated into aqueous core of liposomes by using conventional means. Such bioactive(s) however could be encapsulated in the liposomes by forming their water soluble molecular inclusion complex with cyclodextrins. In this study, we developed Rifampicin (RIF) - 2-hydroxylpropyl-β-cyclodextrin (HP-β-CD) molecular inclusion complex. The HP-β-CD-RIF complex interaction was assessed by using computational analysis (molecular modeling). The HP-β-CD-RIF complex and Isoniazid were co-loaded in the small unilamellar vesicles (SUVs). Further, the developed system was functionalized with transferrin, a targeting moiety. Transferrin functionalized SUVs (Tf-SUVs) could preferentially deliver their payload intracellularly in the endosomal compartment of macrophages. In in vitro study on infected Raw 264.7 macrophage cells revealed that the encapsulated bioactive(s) could eradicate the pathogen more efficiently than free bioactive(s). In vivo studies further revealed that the Tf-SUVs could accumulate and maintain intracellular bioactive(s) concentrations in macrophages. The study suggests Tf-SUVs as a promising module for targeted delivery of a drug combination with improved/optimal therapeutic index and effective clinical outcomes.

Bioresource-Functionalized Quantum Dots for Energy Generation and Storage: Recent Advances and Feature Perspective

The exponential increase in global energy demand in daily life prompts us to search for a bioresource for energy production and storage. Therefore, in developing countries with large populations, there is a need for alternative energy resources to compensate for the energy deficit in an environmentally friendly way and to be independent in their energy demands. The objective of this review article is to compile and evaluate the progress in the development of quantum dots (QDs) for energy generation and storage. Therefore, this article discusses the energy scenario by presenting the basic concepts and advances of various solar cells, providing an overview of energy storage systems (supercapacitors and batteries), and highlighting the research progress to date and future opportunities. This exploratory study will examine the systematic and sequential advances in all three generations of solar cells, namely perovskite solar cells, dye-sensitized solar cells, Si cells, and thin-film solar cells. The discussion will focus on the development of novel QDs that are economical, efficient, and stable. In addition, the current status of high-performance devices for each technology will be discussed in detail. Finally, the prospects, opportunities for improvement, and future trends in the development of cost-effective and efficient QDs for solar cells and storage from biological resources will be highlighted.

Nanobiotics against antimicrobial resistance: harnessing the power of nanoscale materials and technologies

Given the spasmodic increment in antimicrobial resistance (AMR), world is on the verge of “post-antibiotic era”. It is anticipated that current SARS-CoV2 pandemic would worsen the situation in future, mainly due to the lack of new/next generation of antimicrobials. In this context, nanoscale materials with antimicrobial potential have a great promise to treat deadly pathogens. These functional materials are uniquely positioned to effectively interfere with the bacterial systems and augment biofilm penetration. Most importantly, the core substance, surface chemistry, shape, and size of nanomaterials define their efficacy while avoiding the development of AMR. Here, we review the mechanisms of AMR and emerging applications of nanoscale functional materials as an excellent substitute for conventional antibiotics. We discuss the potential, promises, challenges and prospects of nanobiotics to combat AMR.

Recent Developments in Drug Delivery for Treatment of Tuberculosis by Targeting Macrophages

Tuberculosis (TB) is among the greatest public health and safety concerns in the 21st century, Mycobacterium tuberculosis, which causes TB, infects alveolar macrophages and uses these cells as one of its primary sites of replication. The current TB treatment regimen, which consist of chemotherapy involving a combination of 3-4 antimicrobials for a duration of 6-12 months, is marked with significant side effects, toxicity, and poor compliance. Targeted drug delivery offers a strategy that could overcome many of the problems of current TB treatment by specifically targeting infected macrophages. Recent advances in nanotechnology and material science have opened an avenue to explore drug carriers that actively and passively target macrophages. This approach can increase the drug penetration into macrophages by using ligands on the nanocarrier that interact with specific receptors for macrophages. This review encompasses the recent development of drug carriers specifically targeting macrophages actively and passively. Future directions and challenges associated with development of effective TB treatment is also discussed.

Highly Porous Composite Scaffolds Endowed with Antibacterial Activity for Multifunctional Grafts in Bone Repair

The present study deals with the development of multifunctional biphasic calcium phosphate (BCP) scaffolds coated with biopolymers—poly(ε-caprolactone) (PCL) or poly(ester urea) (PEU)—loaded with an antibiotic drug, Rifampicin (RFP). The amounts of RFP incorporated into the PCL and PEU-coated scaffolds were 0.55 ± 0.04 and 0.45 ± 0.02 wt%, respectively. The in vitro drug release profiles in phosphate buffered saline over 6 days were characterized by a burst release within the first 8h, followed by a sustained release. The Korsmeyer–Peppas model showed that RFP release was controlled by polymer-specific non-Fickian diffusion. A faster burst release (67.33 ± 1.48%) was observed for the PCL-coated samples, in comparison to that measured (47.23 ± 0.31%) for the PEU-coated samples. The growth inhibitory activity against Escherichia coli and Staphylococcus aureus was evaluated. Although the RFP-loaded scaffolds were effective in reducing bacterial growth for both strains, their effectiveness depends on the particular bacterial strain, as well as on the type of polymer coating, since it rules the drug release behavior. The low antibacterial activity demonstrated by the BCP-PEU-RFP scaffold against E. coli could be a consequence of the lower amount of RFP that is released from this scaffold, when compared with BCP-PCL-RFP. In vitro studies showed excellent cytocompatibility, adherence, and proliferation of human mesenchymal stem cells on the BCP-PEU-RFP scaffold surface. The fabricated highly porous scaffolds that could act as an antibiotic delivery system have great potential for applications in bone regeneration and tissue engineering, while preventing bacterial infections.

Preparation of Curdlan sulphate - Chitosan nanoparticles as a drug carrier to target Mycobacterium smegmatis infected macrophages

In this study, curdlan sulphate - chitosan nanoparticles were prepared through polyelectrolyte complexing at a mass ratio of 2:1 respectively. The curdlan was produced by fermentation with Agrobacterium sp. ATCC 31750, which was then sulphated to form the polyanionic polymer. A first-line tuberculosis drug, Rifampicin and a phytochemical, DdPinitol, were encapsulated into Curdlan Sulphate (CS) - Chitosan Nanoparticles (C) (CSC NPs) of size 205.41 ± 7.24 nm. The drug release kinetics followed a Weibull model with initial burst release (48 % Rifampicin and 27 % d-Pinitol within 6 h), followed by a sustained release. The prepared CSC: d-PIN + RIF NPs was cytocompatible and entered the M.smegmatis infected macrophages through multiple endocytic pathways including clathrin, caveolae and macropinocytosis. They showed superior bactericidal activity (2.4-2.7 fold) within 4 h when compared to free drug Rifampicin (1.6 fold). The drug encapsulated CSC: RIF suppressed the pro-inflammatory gene (TNF-α by 3.66 ± 0.19 fold) and CSC: d-PIN + RIF increased expression of the anti-inflammatory gene (IL-10 by 13.09 ± 0.47 fold). Expression of TGF- β1 gene also increased when treated with CSC: d-PIN + RIF (13.00 ± 0.19 fold) which provided the immunomodulatory activity of the encapsulated CSC NPs. Thus, curdlan sulphate - chitosan polyelectrolyte complex can be a potential nanocarrier matrix for intracellular delivery of multiple drugs.

Fused deposition modelling for the development of drug loaded cardiovascular prosthesis

Cardiovascular diseases constitute a number of conditions which are the leading cause of death globally. To combat these diseases and improve the quality and duration of life, several cardiac implants have been developed, including stents, vascular grafts and valvular prostheses. The implantation of these vascular prosthesis has associated risks such as infection or blood clot formation. In order to overcome these limitations medicated vascular prosthesis have been previously used. The present paper describes a 3D printing method to develop medicated vascular prosthesis using fused deposition modelling (FDM) technology. For this purpose, rifampicin (RIF) was selected as a model molecule as it can be used to prevent vascular graft prosthesis infection. Thermoplastic polyurethane (TPU) and RIF were combined using hot melt extrusion (HME) to obtain filaments containing RIF concentrations ranging between 0 and 1% (w/w). These materials are capable of providing RIF release for periods ranging between 30 and 80 days. Moreover, TPU-based materials containing RIF were capable of inhibiting the growth of Staphylococcus aureus. This behaviour was observed even for TPU-based materials containing RIF concentrations of 0.1% (w/w). TPU containing 1% (w/w) of RIF showed antimicrobial properties even after 30 days of RIF release. Alternatively, these methods were used to prepare dipyridamole containing TPU filaments. Finally, using a dual extrusion 3D printer vascular grafts containing both drugs were prepared.

The Role of Metallic Nanoparticles in Inhibition of Mycobacterium Tuberculosis and Enhances Phagosome Maturation into the Infected Macrophage

This review focuses on the role of gallium (Ga) nanoparticles (NPs) to enhance phagosome maturation into the Mycobacterium tuberculosis-infected macrophage and the role of magnetic iron NPs as nanocarriers of antituberculosis drugs. The literature shows that silver (Ag) and zinc oxide (ZnO) NPs with dimensions less than 10 nm can penetrate directly through the macrophage bilayer membrane. Ag NPs increase the permeability membrane by motiving the aggregation of proteins in the periplasmic space and forming nano-sized pores. ZnO NPs can interact with the membrane of M. tuberculosis, which leads to the formation of surface pores and the release of intracellular nucleotides. The colloidal Ag:ZnO mixture NPs with 1:1 ratio can eliminate M. tuberculosis and shows the lowest cytotoxicity effects on MCF-7 and THP-1 cell lines. Ag/ZnO nanocrystals are not able to kill M. tuberculosis alone ex-vivo. Hence, bimetallic gold (Au)/Ag NPs possessed high efficiency to inhibit M. tuberculosis in an ex-vivo THP-1 infection model. Co-delivery of mixed MeNPs into a polymeric carrier collaborated to selective uptake by macrophages through passive targeting, initial burst release of ions from the encapsulated metallic (Me) NPs, and eventually, reduction of MeNPs toxicity, and plays a pivotal role in increasing the antitubercular activity compared to use alone. In addition, Ga NPs can import drugs to the macrophage, inhibit M. tuberculosis growth, and reduce the inhibition of phagosome maturation. Magnetic encapsulated NPs exhibited good drug release properties and might be suitable as carriers of antituberculosis drugs.

Breast intraductal nanoformulations for treating ductal carcinoma in situ I: Exploring metal-ion complexation to slow ciclopirox release, enhance mammary persistence and efficacy

INTRODUCTION

Ductal Carcinoma In Situ (DCIS) represents a significant fraction (~20-25%) of all newly diagnosed breast cancer cases and, if left untreated, a significant fraction of patients will progress to invasive disease. Surgery is the only treatment option. Ciclopirox (CPX), an FDA-approved antifungal drug, has exhibited promising antitumor activity by down-regulating the expression of vital antiapoptotic cellular proteins and inhibiting the genetic expression of several oncogenic pathways. In this study, the feasibility of using nanoscale delivery systems to control release and prolong mammary tissue persistence of a lipophilic metal complex of CPX and Zinc (CPXZn) after intraductal administration was investigated.

METHODS

CPX and CPX-Zn nanosuspensions (NSs) were prepared using an evaporative nanoprecipitation-ultra-sonication method. Flash nanoprecipitation was used to prepare PLGA nanoparticles (NPs) loaded with CPXZn. Our established orthotopic DCIS rat model was used to evaluate efficacy. Briefly, two days after 13762 Mat B III cell intraductal inoculation, rats were divided into treatment groups and a single intraductal injection of CPX NS, CPX-Zn NS or CPX-Zn NPs was administered. In the first study arm, the efficacy of CPX NS (1, 3, 5 mg/duct) was evaluated. In the second arm, the in vivo efficacy of CPX NS, CPX-Zn NS and CPX-Zn loaded NPs was evaluated and compared at equivalent CPX doses. The mammary persistence of CPX from CPX NS, CPX-Zn NS, and CPX-Zn PLGA NPs was also assessed.

RESULTS

CPX-Zn complex was successfully synthesized and characterized by several spectral analyses. CPX release was slowed from the CPX-Zn NS and further slowed by incorporating CPX-Zn into PLGA NPs as compared to the CPX NS with release half times following the order: CPX NS < CPX-Zn NS << CPX-Zn NP. Intraductal CPX NS administration was dose and time dependent in suppressing tumor initiation suggesting prolonged mammary exposure may improve efficacy. In the second arm, mammary tissue persistence of CPX followed the rank order CPX NS < CPX-Zn NS << CPX-Zn NP at 6 h and 48 h post-administration. Prolonged mammary CPX exposure was highly correlated to improved efficacy. Prolonged CPX tissue persistence, attributed to slower release from the zinc complex and the PLGA NPs, resulted in a 5-fold dose reduction compared to the CPX NS.

CONCLUSIONS

The current results demonstrate that slowing drug release in the mammary duct after intraductal administration overcomes the rapid ductal clearance of CPX, prolongs mammary tissue persistence, improves efficacy against DCIS lesions in vivo, and requires 5-fold less CPX to achieve equivalent efficacy. The studies also provide a strategic path forward for developing a locally administered drug delivery system for treating DCIS, for which no primary chemotherapy option is available.

Antimicrobial Activity and Mechanism of Functionalized Quantum Dots

An essential characteristic of quantum dots (QDs) is their antimicrobial activity. Compared with conventional antibiotics, QDs not only possess photoluminescence properties for imaging and photodynamic therapy but also have high structural stability. To enhance their antimicrobial efficiency, QDs usually are functionalized by polymers, including poly(ethylene glycol), polyethyleneimine, and poly-l-lysine. Also, QDs conjugated with polymers, such as poly(vinylpyrrolidone) and polyvinylidene fluoride, are prepared as antimicrobial membranes. The main antimicrobial mechanisms of QDs are associated with inducing free radicals, disrupting cell walls/membranes, and arresting gene expression. The different mechanisms from traditional antibiotics allow QDs to play antimicrobial roles in multi-drug-resistant bacteria and fungi. Since the toxicity of the QDs on animal cells is relatively low, they have broad application in antimicrobial research as an effective alternative of traditional antibiotics.

In Vitro and In Vivo Activities of Zinc Linolenate, a Selective Antibacterial Agent against Helicobacter pylori

Helicobacter pylori is a major global pathogen, and its infection represents a key factor in the etiology of various gastric diseases, including gastritis, peptic ulcers, and gastric carcinoma. The efficacy of current standard treatment for H. pylori infection including two broad-spectrum antibiotics is compromised by toxicity toward the gut microbiota and the development of drug resistance, which will likely only be resolved through novel and selective antibacterial strategies. Here, we synthesized a small molecule, zinc linolenate (ZnLla), and investigated its therapeutic potential for the treatment of H. pylori infection. ZnLla showed effective antibacterial activity against standard strains and drug-resistant clinical isolates of H. pyloriin vitro with no development of resistance during continuous serial passaging. The mechanisms of ZnLla action against H. pylori involved the disruption of bacterial cell membranes and generation of reactive oxygen species. In mouse models of multidrug-resistant H. pylori infection, ZnLla showed in vivo killing efficacy comparable and superior to the triple therapy approach when use as a monotherapy and a combined therapy with omeprazole, respectively. Moreover, ZnLla treatment induces negligible toxicity against normal tissues and causes minimal effects on both the diversity and composition of the murine gut microbiota. Thus, the high degree of selectivity of ZnLla for H. pylori provides an attractive candidate for novel targeted anti-H. pylori treatment.

Antibacterial Activity of combinatorial treatments composed of transition-metal/antibiotics against Mycobacterium tuberculosis

Notwithstanding evidence that tuberculosis (TB) is declining, one of the greatest concerns to public health is the emergence and spread of multi-drug resistant strains of Mycobacterium tuberculosis (MDR-TB). MDR-TB are defined as strains which are resistant to at least isoniazid (INH) and rifampicin, the two most potent TB drugs, and their increasing incidence is a serious concern. Recently, notable efforts have been spent on research to pursue novel treatments against MDR-TB, especially on synergistic drug combinations as they have the potential to improve TB treatment. Our research group has previously reported promising synergistic antimicrobial effects between transition-metal compounds and antibiotics in Gram-negative and Gram-positive bacteria. In this work, we evaluated antimycobacterial activity of transition-metals/antibiotics combinatorial treatments against first-line drug resistant strains of Mycobacterium tuberculosis. Our data showed that INH/AgNO₃ combinatorial treatment had an additive effect (bactericidal activity) in an isoniazid-resistant clinical strain of Mycobacterium tuberculosis. Moreover, in vitro evaluation of cytotoxicity induced by both, the individual tratments of AgNO₃ and INH and the combinatorial treatment of INH/AgNO₃ in murine RAW 264.7 macrophages and human A549 lung cells; showed no toxic effects. Together, this data suggests that the INH/AgNO₃ combinatorial treatment could be used in the development of new strategies to treat resistant strains of Mycobacterium tuberculosis.

Zinc phosphate-based nanoparticles as a novel antibacterial agent: in vivo study on rats after dietary exposure

Background

Development of new nanomaterials that inhibit or kill bacteria is an important and timely research topic. For example, financial losses due to infectious diseases, such as diarrhea, are a major concern in livestock productions around the world. Antimicrobial nanoparticles (NPs) represent a promising alternative to antibiotics and may lower antibiotic use and consequently spread of antibiotic resistance traits among bacteria, including pathogens.

Results

Four formulations of zinc nanoparticles (ZnA, ZnB, ZnC, and ZnD) based on phosphates with spherical (ZnA, ZnB) or irregular (ZnC, ZnD) morphology were prepared. The highest in vitro inhibitory effect of our NPs was observed against Staphylococcus aureus (inhibitory concentration values, IC₅₀, ranged from 0.5 to 1.6 mmol/L), followed by Escherichia coli (IC₅₀ 0.8-1.5 mmol/L). In contrast, methicillin resistant S. aureus (IC₅₀ 1.2-4.7 mmol/L) was least affected and this was similar to inhibitory patterns of commercial ZnO-based NPs and ZnO. After the successful in vitro testing, the in vivo study with rats based on dietary supplementation with zinc NPs was conducted. Four groups of rats were treated by 2,000 mg Zn/kg diet of ZnA, ZnB, ZnC, and ZnD, for comparison two groups were supplemented by 2,000 mg Zn/kg diet of ZnO-N and ZnO, and one group (control) was fed only by basal diet. The significantly higher (P < 0.05) Zn level in liver and kidney of all treated groups was found, nevertheless Zn NPs did not greatly influence antioxidant status of rats. However, the total aerobic and coliform bacterial population in rat feces significantly decreased (P < 0.05) in all zinc groups after 30 d of the treatment. Furthermore, when compared to the ZnO group, ZnA and ZnC nanoparticles reduced coliforms significantly more (P < 0.05).

Conclusions

Our results demonstrate that phosphate-based zinc nanoparticles have the potential to act as antibiotic agents.

Expression and significance of quantum dots in RAW 264.7 macrophages

The aim of the present study was to investigate the clinical application and utility of CdSe/ZnS quantum dots (QDs) in tracing RAW 264.7 macrophages. RAW 264.7 cells and QDs at various concentrations were co-cultured for 24 h, and the fluorescence intensity of the macrophages was determined at various time points. The mRNA expression levels of genes encoding inflammatory cytokines [tumor necrosis factor (TNF)-α and interleukin (IL)-1β] were determined, and cellular assays were performed to investigate the activation, proliferation and apoptosis of RAW 264.7 cells. The QDs were engulfed by the macrophages, and the fluorescence intensity of RAW 264.7 cells increased with increasing concentration and time. The IL-1β mRNA level increased significantly at 50 µg/ml QDs, and that of TNF-α increased significantly at 100 µg/ml QDs. Accelerated proliferation of RAW 264.7 cells was observed at 50 and 100 µg/ml QDs; however, no increase in apoptosis of RAW 264.7 cells was observed in co-culture. CdSe/ZnS QDs may be used as tracers due to the fluorescence intensity of RAW 264.7 cells increasing with increasing QD concentration and time, resulting in the activation of macrophages and significant increases in proliferation at 50 and 100 µg/ml QDs compared with in the absence of QDs. The change in QD concentration was not significantly associated with the proliferation and apoptosis of RAW 264.7 macrophages.

Enhancing Whole Phage Therapy and Their Derived Antimicrobial Enzymes through Complex Formulation

The resurgence of research into phage biology and therapy is, in part, due to the increasing need for novel agents to treat multidrug-resistant infections. Despite a long clinical history in Eastern Europe and initial success within the food industry, commercialized phage products have yet to enter other sectors. This relative lack of success is, in part, due to the inherent biological limitations of whole phages. These include (but are not limited to) reaching target sites at sufficiently high concentrations to establish an infection which produces enough progeny phages to reduce the bacterial population in a clinically meaningful manner and the limited host range of some phages. Conversely, parallels can be drawn between antimicrobial enzymes derived from phages and conventional antibiotics. In the current article the biological limitations of whole phage-based therapeutics and their derived antimicrobial enzymes will be discussed. In addition, the ability of more complex formulations to address these issues, in the context of medical and non-medical applications, will also be included.

Modulation of quantum dots and clearance of Helicobacter pylori with synergy of cell autophagy

Helicobacter pylori (Hp) is one type of Gram-negative pathogenic bacterium that colonizes and causes a wide range of gastric diseases. Once Hp penetrates into cells, the currently recognized triple or quadruple therapy often loses effectiveness. Recent evidence suggests that autophagy is closely associated with Hp infection, and can play an important role in the eradication of Hp. More importantly, certain types of quantum dots (QDs) can induce and modulate cellular autophagy, and can be developed into conjugates making QDs potential candidates as new anti-Hp agents.