Significance of controlling crystallization mechanisms and kinetics in pharmaceutical systems

Nutraceutical approaches to metabolic syndrome

Metabolic Syndrome (MetS), affecting at least 30% of adults in the Western World, is characterized by three out of five variables, from high triglycerides, to elevated waist circumference and blood pressure. MetS is not characterized by elevated cholesterolemia, but is rather the consequence of a complex interaction of factors generally leading to increased insulin resistance. Drug treatments are of difficult handling, whereas well-characterized nutraceuticals may offer an effective alternative. Among these, functional foods, e.g. plant proteins, have been shown to improve insulin resistance and reduce triglyceride secretion. Pro- and pre-biotics, that are able to modify intestinal microbiome, reduce absorption of specific nutrients and improve the metabolic handling of energy-rich foods. Finally, specific nutraceuticals have proven to be of benefit, in particular, red-yeast rice, berberine, curcumin as well as vitamin D. All these can improve lipid handling by the liver as well as ameliorate insulin resistance. While lifestyle approaches, such as with the Mediterranean diet, may prove to be too complex for the single patient, better knowledge of selected nutraceuticals and more appropriate formulations leading to improved bioavailability will certainly widen the use of these agents, already in large use for the management of these very frequent patient groups. Key messages Functional foods, e.g. plant proteins, improve insulin resistance. Pro- and pre-biotics improve the metabolic handling of energy-rich foods. Nutraceutical can offer a significant help in handling MetS patients being part of lifestyle recommendations.

A Critical Review of Properties and Analytical Methods for the Determination of Oxytetracyline in Biological and Pharmaceutical Matrices

Antibiotics have an unquestionable importance in the treatment of many infections. Oxytetracycline is an antibiotic belonging to the class of tetracyclines, available for use in human and veterinary medicine. Development of analytical methods that prove the quality and efficacy of these drugs is fundamentally important to the pharmaceutical industry. In this context, the research presents an overview of the analytical profile of oxytetracycline, describing its chemical and pharmacological properties, and analytical methods for quantification of this drug in biological samples and pharmaceutical products. Oxytetracycline can be analyzed in these matrices by many types of methodologies. However, high-performance liquid chromatography is the most widely used, being recommended by official compendia. This kind of study can be useful to support the development of new efficient and sustainable analytical methods that may be utilized in the quality control routine of oxytetracycline in pharmaceutical products and pharmacokinetic monitoring in biological samples.

Dendrimer-mediated approaches for the treatment of brain tumor

Worldwide, the cancer appeared as one of the most leading cause of morbidity and mortality. Among the various cancer types, brain tumors are most life threatening with low survival rate. Every year approximately 238,000 new cases of brain and other central nervous system tumors are diagnosed. The dendrimeric approaches have a huge potential for diagnosis and treatment of brain tumor with targeting abilities of molecular cargoes to the tumor sites and the efficiency of crossing the blood brain barrier and penetration to brain after systemic administration. The various generations of dendrimers have been designed as novel targeted drug delivery tools for new therapies including sustained drug release, gene therapy, and antiangiogenic activities. At present era, various types of dendrimers like PAMAM, PPI, and PLL dendrimers validated them as milestones for the treatment and diagnosis of brain tumor as well as other cancers. This review highlights the recent research, opportunities, advantages, and challenges involved in development of novel dendrimeric complex for the therapy of brain tumor.

Ginger hexane extract suppresses RANKL-induced osteoclast differentiation

Osteoporosis is a debilitating disease caused by decreased bone density. Compounds with anti-osteoclastic activity, such as bisphosphonates, may help in the prevention and treatment of osteoporosis. Herein, we determined the inhibitory effects of ginger hexane extract (GHE) on receptor activator of nuclear factor kappa-B ligand (RANKL)-induced osteoclastogenesis in RAW264.7 cells. The results showed that GHE (1) suppressed osteoclast differentiation and the formation of actin rings; (2) inhibited the expression of Nfatc1, a master transcriptional factor for osteoclast differentiation, in a dose-dependent manner (10-20 μg/mL); and (3) inhibited other osteoclastogenesis-related genes, such as Oscar, Dc-stamp, Trap, and Mmp9. These findings suggest that GHE may be used to prevent and treat osteoporosis by inhibiting osteoclast differentiation.

Recent advances in testing of microsphere drug delivery systems

INTRODUCTION

This review discusses advances in the field of microsphere testing.

AREAS COVERED

In vitro release-testing methods such as sample and separate, dialysis membrane sacs and USP apparatus IV have been used for microspheres. Based on comparisons of these methods, USP apparatus IV is currently the method of choice. Accelerated in vitro release tests have been developed to shorten the testing time for quality control purposes. In vitro-in vivo correlations using real-time and accelerated release data have been developed, to minimize the need to conduct in vivo performance evaluation. Storage stability studies have been conducted to investigate the influence of various environmental factors on microsphere quality throughout the product shelf life. New tests such as the floating test and the in vitro wash-off test have been developed along with advancement in characterization techniques for other physico-chemical parameters such as particle size, drug content, and thermal properties.

EXPERT OPINION

Although significant developments have been made in microsphere release testing, there is still a lack of guidance in this area. Microsphere storage stability studies should be extended to include microspheres containing large molecules. An agreement needs to be reached on the use of particle sizing techniques to avoid inconsistent data. An approach needs to be developed to determine total moisture content of microspheres.

New diterpenoids from Sapium discolor

Chemical fractionation of the ethanolic extract generated from the twigs and leaves of Sapium discolor led to the isolation and identification of four new macrocyclic diterpenoids including three members of the rare casbane family, sapidisins A-C (1-3), and an analog of the cembrane class, sapidisin D (4), a new 3,4-seco ent-kaurane diterpenoid (5), and 18 known phenolic compounds. Their structures were elucidated by comprehensive spectroscopic analyses especially 1D NMR (1)H-(1)H couplings and 2D NMR ROESY data. The discovery of 1-4 from S. discolor provides a clue for further study on the biogenetic evolution of the widely existent tigliane-type diterpenoids in the Sapium species.

Three new monoterpenoid indole alkaloids from Vinca major

Three new monoterpenoid indole alkaloids, 19-hydroxyl-10-methoxy-19, 20-dihydrovinorine (1), 19-O-acetyl-10-methoxy-19, 20-dihydrovinorine (2), and 19, 21α-dihydroxyl-10-methoxy-19, 20-dihydrovinorine (3), along with five known analogues (4-8), were isolated from the whole plants of Vinca major. The new structures were elucidated by extensive NMR and MS analysis and comparison with known compounds. In addition, compounds 1-3 were evaluated for their cytotoxicities against five human cancer cell lines.

New α-glucosidase inhibiting anthracenone from the barks of Harungana madagascariensis Lam

Two new 10-hydroxy-9(10H)-anthracenone, madagascenone A (1) and B (2), were isolated from the barks of Harungana madagascariensis Lam. The structures of the compounds were determined using 1D- and 2D-NMR and mass spectroscopic techniques. Both of the compounds showed an in vitro α-glucosidase inhibition with IC₅₀ = 69.9 ± 4.21 and 122.3 ± 1.13 μM, respectively, more potent than the standard acarbose (IC₅₀ = 840 ± 1.23 μM).

Secondary metabolites extracted from marine sponge associated Comamonas testosteroni and Citrobacter freundii as potential antimicrobials against MDR pathogens and hypothetical leads for VP40 matrix protein of Ebola virus: an in vitro and in silico investigation

The current study explores therapeutic potential of metabolites extracted from marine sponge (Cliona sp.)-associated bacteria against MDR pathogens and predicts the binding prospective of probable lead molecules against VP40 target of Ebola virus. The metabolite-producing bacteria were characterized by agar overlay assay and as per the protocols in Bergey's manual of determinative bacteriology. The antibacterial activities of extracted metabolites were tested against clinical pathogens by well-diffusion assay. The selected metabolite producers were characterized by 16S rDNA sequencing. Chemical screening and Fourier Transform Infrared (FTIR) analysis for selected compounds were performed. The probable lead molecules present in the metabolites were hypothesized based on proximate analysis, FTIR data, and literature survey. The drug-like properties and binding potential of lead molecules against VP40 target of Ebola virus were hypothesized by computational virtual screening and molecular docking. The current study demonstrated that clear zones around bacterial colonies in agar overlay assay. Antibiotic sensitivity profiling demonstrated that the clinical isolates were multi-drug resistant, however; most of them showed sensitivity to secondary metabolites (MIC-15 μl/well). The proximate and FTIR analysis suggested that probable metabolites belonged to alkaloids with O-H, C-H, C=O, and N-H groups. 16S rDNA characterization of selected metabolite producers demonstrated that 96% and 99% sequence identity to Comamonas testosteroni and Citrobacter freundii, respectively. The docking studies suggested that molecules such as Gymnastatin, Sorbicillactone, Marizomib, and Daryamide can designed as probable lead candidates against VP40 target of Ebola virus.

Chemical composition of the pods of Albizia polyphylla

In this study, we report for the first time the presence of alkaloids belonging to β-carboline type in the pods of the endemic Albizia polyphylla from Madagascar. Three major alkaloids were isolated and structurally identified as: 1-methyl-β-carboline, (+)-(R)-1-methyl-1,2,3,4-tetrahydro-β-carboline and (-)-(S)-1,2-dimethyl-1,2,3,4-tetrahydro-β-carboline.

Preparation and characterization of bioadhesive controlled-release gels of cidofovir for vaginal delivery

The aim of this study was to develop mucoadhesive and thermosensitive gels for vaginal delivery that would be able to provide a controlled release of the model drug, cidofovir. The study also monitored the drug's potential antiviral properties. Cidofovir was put into the form of a vaginal gel, using mucoadhesive and thermosensitive polymers such as chitosan, Carbopol 974P, HPMC, and poloxamer 407. The physicopharmaceutical properties and stability of the vaginal gel formulations were evaluated. The gel formulation which was prepared with HPMC K100M exhibited the highest viscosity, as well as maximum adhesiveness, cohesiveness, and mucoadhesion values. The results of antiviral activity studies, which used the bovine herpes virus type 1 virus infection in vitro model using Vero cells, demonstrated the antiherpetic effect of the cidofovir gel containing HPMC K100M, at least under in vitro conditions. The study found that a mucoadhesive vaginal gel containing cidofovir can be a promising and innovative alternative therapeutic system for the treatment of genital herpes simplex virus and human papilloma virus induced infections in women.

Synthesis of dual-functional targeting probes for cancer theranostics based on iron oxide nanoparticles coated by centipede-like polymer connected with pH-responsive anticancer drug

A tumor-targeted and pH-responsive drug release system based on superparamagnetic iron oxide nanoparticles (IONPs) coated by poly(ethylene glycol) (PEG) and dodecylamine (DDA)-modified polyitaconic acid (PIA) connecting with bortezomib (BTZ) (PIA-PEG-DDA-BTZ@IOs) has been constructed and characterized. The anticancer drug BTZ was first conjugated using dopamine as the linker via catechol borate ester bond, which is acid cleavable and used as an ideal pH-responsive drug release system. The IONPs were then coated by PIA-PEG-DDA-BTZ to form micelles with good biocompatibility. The conjugates were further designed to target liver cancer cells overexpressing vascular endothelial growth factor (VEGF) by the targeting molecule anti-vascular endothelial growth factor (anti-VEGF). The magnetic resonance imaging showed that the targeting capability of IONPs-anti-VEGF conjugates to Hep G2 cells was more significant than that of non-anti-VEGF IONPs. From the above, this kind of novel dual-functional targeting probe could provide a new idea for the diagnosis and treatment of cancer.

Programmed cell delivery from biodegradable microcapsules for tissue repair

Injectable and resorbable hydrogels are an extremely attractive class of biomaterials. They make it possible to fill tissue defects accurately with an undoubtedly minimally invasive approach and to locally deliver cells that support repair or regeneration processes. However, their use as a cell carrier is often hindered by inadequate diffusion in bulk. A possible strategy for overcoming this transport limitation might be represented by injection of rapidly degradable cell-loaded microcapsules, so that maximum material thickness is limited by sphere radius. Here, the possibility of achieving programmable release of viable cells from alginate-based microcapsules was explored in vitro, by evaluating variations in material stability resulting from changes in hydrogel composition and assessing cell viability after encapsulation and in vitro release from microcapsules. Degradation of pure alginate microspheres was varied from a few days to several weeks by varying sodium alginate and calcium chloride concentrations. The addition of poloxamer was also found to accelerate degradation significantly, with capsule breakdown almost complete by two weeks, while chitosan was confirmed to strengthen alginate cross-linking. The presence of viable cells inside microspheres was revealed after encapsulation, and released cells were observed for all the formulations tested after a time interval dependent on bead degradation speed. These findings suggest that it may be possible to fine tune capsule breakdown by means of simple changes in material formulation and regulate, and eventually optimize, cell release for tissue repair.

In silico optimization of pharmacokinetic properties and receptor binding affinity simultaneously: a 'parallel progression approach to drug design' applied to β-blockers

The present work exploits the potential of in silico approaches for minimizing attrition of leads in the later stages of drug development. We propose a theoretical approach, wherein 'parallel' information is generated to simultaneously optimize the pharmacokinetics (PK) and pharmacodynamics (PD) of lead candidates. β-blockers, though in use for many years, have suboptimal PKs; hence are an ideal test series for the 'parallel progression approach'. This approach utilizes molecular modeling tools viz. hologram quantitative structure activity relationships, homology modeling, docking, predictive metabolism, and toxicity models. Validated models have been developed for PK parameters such as volume of distribution (log Vd) and clearance (log Cl), which together influence the half-life (t1/2) of a drug. Simultaneously, models for PD in terms of inhibition constant pKi have been developed. Thus, PK and PD properties of β-blockers were concurrently analyzed and after iterative cycling, modifications were proposed that lead to compounds with optimized PK and PD. We report some of the resultant re-engineered β-blockers with improved half-lives and pKi values comparable with marketed β-blockers. These were further analyzed by the docking studies to evaluate their binding poses. Finally, metabolic and toxicological assessment of these molecules was done through in silico methods. The strategy proposed herein has potential universal applicability, and can be used in any drug discovery scenario; provided that the data used is consistent in terms of experimental conditions, endpoints, and methods employed. Thus the 'parallel progression approach' helps to simultaneously fine-tune various properties of the drug and would be an invaluable tool during the drug development process.

Label-free detection and characterization of the binding of hemagglutinin protein and broadly neutralizing monoclonal antibodies using terahertz spectroscopy

Hemagglutinin (HA) is the main surface glycoprotein of the influenza A virus. The H9N2 subtype influenza A virus is recognized as the most possible pandemic strain as it has crossed the species barrier, infecting swine and humans. We use terahertz spectroscopy to study the hydration shell formation around H9 subtype influenza A virus's HA protein (H9 HA) as well as the detection of antigen binding of H9 HA with the broadly neutralizing monoclonal antibody. We observe a remarkable concentration dependent nonlinear response of the H9 HA, which reveals the formation process of the hydration shell around H9 HA molecules. Furthermore, we show that terahertz dielectric properties of the H9 HA are strongly affected by the presence of the monoclonal antibody F10 and that the terahertz dielectric loss tangent can be used to detect the antibody binding at lower concentrations than the standard ELISA test.

Diagnose human colonic tissues by terahertz near-field imaging

Based on a terahertz (THz) pipe-based near-field imaging system, we demonstrate the capability of THz imaging to diagnose freshly surgically excised human colonic tissues. Through THz near-field scanning the absorbance of the colonic tissues, the acquired images can clearly distinguish cancerous tissues from healthy tissues fast and automatically without pathological hematoxylin and eosin stain diagnosis. A statistical study on 58 specimens (20 healthy tissues and 38 tissues with tumor) from 31 patients (mean age: 59 years; range: 46 to 79 years) shows that the corresponding diagnostic sensitivity and specificity on colonic tissues are both 100%. Due to its capability to perform quantitative analysis, our study indicates the potential of the THz pipe-based near-field imaging for future automation on human tumor pathological examinations.

Computational classification models for predicting the interaction of drugs with P-glycoprotein and breast cancer resistance protein

P-glycoprotein (P-gp/ABCB1) and breast cancer resistance protein (BCRP/ABCG2) are two members of the adenosine triphosphate (ATP) binding cassette (ABC) family of transporters which function as membrane efflux transporters and display considerable substrate promiscuity. Both are known to significantly influence the absorption, distribution and elimination of drugs, mediate drug-drug interactions and contribute to multiple drug resistance (MDR) of cancer cells. Correspondingly, timely characterization of the interaction of novel leads and drug candidates with these two transporters is of great importance. In this study, several computational classification models for prediction of transport and inhibition of P-gp and BCRP, respectively, were developed based on newly compiled and critically evaluated experimental data. Artificial neural network (ANN) and support vector machine (SVM) ensemble based models were explored, as well as knowledge-based approaches to descriptor selection. The average overall classification accuracy of best performing models was 82% for P-gp transport, 88% for BCRP transport, 89% for P-gp inhibition and 87% for BCRP inhibition, determined across an array of different test sets. An analysis of substrate overlap between P-gp and BCRP was also performed. The accuracy, simplicity and interpretability of the proposed models suggest that they could be of significant utility in the drug discovery and development settings.

KAISO inhibition: an atomic insight

In today's world, the pursuit of a novel anti-cancer agent remains top priority because of the fact that the global burden of this malady is continuously increasing. Our work is no different from others in searching for new therapeutic solutions. To achieve this, we are looking into Epigenetics, the phenomenon governed by hypermethylation and hypomethylation of tumor suppressor genes and oncogenes, respectively. Our target for this study is an important intermediary methyl-CpG binding protein named kaiso. In our study, we have used the X-ray crystallographic structure of Kaiso for virtual screening and molecular dynamics simulations to study the binding modes of possible inhibitors. The C2H2 domain comprising LYS539 was used for screening the inter bio screen Database having 48,531 natural compounds. Our approach of using computer-aided drug designing methods helped us to remove the execrable compounds and narrowed our focus on a selected few for molecular simulation studies. The top ranked compound (chem. ID 28127) exhibited the highest binding affinity and was also found to be stable throughout the 20 ns timeframe. This compound is therefore a good starting point for developing strong inhibitors.

Aptamer-gelatin composite for a trigger release system mediated by oligonucleotide hybridization

Nucleic acid aptamers not only specifically bind to their target proteins with high affinity but also form intermolecular hybridization with their complementary oligonucleotides (CO). The hybridization can interrupt aptamer/protein interaction due to the changes of aptamer secondary structure which rely on hybridization length and base-pairing positions. Herein we aim to use this unique property of the aptamers, when combined with gelatin to develop a novel composite with desirable protein release profiles. Platelet-derived growth factor-BB (PDGF-BB) and its aptamer were used as target molecules. Prior to performing the release study, the effects of CO on aptamer-protein interaction were observed by surface plasmon resonance (SPR). The SPR sensorgram indicated that the aptamer dissociated from the bounded proteins when it hybridized with the CO. The aptamer was then immobilized onto streptavidin coated polystyrene particles via biotin/streptavidin interaction. Then, PDGF-BB and aptamer functionalized particles were mixed with gelatin solution and cast as small pieces of composite. The success of the composite preparation was confirmed by flow cytometry and microscopy. PDGF-BB release at several time points was quantified by ELISA. The results showed that the aptamer-gelatin composite could slow the release rate of the proteins from the composite due to strong binding of proteins and aptamers. Once the CO was added to the system, the release rate was significantly enhanced because the aptamer hybridized with the CO and lost its active secondary structure. Therefore, the proteins were triggered to release out from the composite. This work suggests a promising strategy for controlling the release of bioactive molecules in medical treatments.

Polygodial: a contact active antifouling biocide

Ongoing investigation of the candidate antifouling (AF) biocide polygodial (PG) has revealed that this compound may be contact active, whereby it can confer effect while remaining bound within a stable matrix. To test this hypothesis, the AF activity of PG-laced coatings was compared to that of seawater in which PG-laced coatings had been soaked. Four coating types spanning high to low affinity for PG were examined and AF activity was assessed based on inhibition of settlement and metamorphosis of larvae of three fouling organisms: Ciona savignyi Herdman, Mytilus galloprovincialis Lamarck and Spirobranchus caraniferus Gray. Direct exposure to the coatings had a significantly greater impact on larval metamorphosis than indirect exposure to seawater in which the coatings had been soaked. In particular, metamorphosis was almost completely inhibited by high-affinity coatings containing ≥ 200 ng of PG per replicate, while corresponding soaking waters had no detectable effect. These findings support the assertion that PG is contact active.

Immunoadjuvant activity of the nanoparticles' surface modified with mannan

Mannan (MN) is the natural ligand for mannose receptors, which are widely expressed on dendritic cells (DCs). The purpose of this study was to assess the effect of formulation parameters on the immunogenicity of MN-decorated poly (D, L-lactide-co-glycolide) (PLGA) nanoparticles (NPs) in terms of their ability to stimulate DC phenotypic as well as functional maturation. For this purpose, NPs were formulated from either ester-terminated or COOH-terminated PLGA. Incorporation of MN in NPs was achieved through encapsulation, physical adsorption or chemical conjugation. Murine bone marrow derived DCs (BMDCs) were treated with various NP formulations and assessed for their ability to up-regulate DC cell surface markers, secrete immunostimulatory cytokines and to activate allogenic T cell responses. DCs treated with COOH-terminated PLGA-NPs containing chemically conjugated MN (MN-Cov-COOH) have shown superior performance in improving DC biological functions, compared to the rest of the formulations tested. This may be attributed to the higher level of MN incorporation in the former formulation. Incorporation of MN in PLGA NPs through chemical conjugation can lead to enhanced DC maturation and stimulatory function. This strategy may be used to develop more effective PLGA-based vaccine formulations.

Effects of dosing protocol on distribution of propranolol in periocular tissues after topical ocular instillation

PURPOSE

Our previous study demonstrated that topical ocular instillation can deliver effective concentrations of propranolol in the periocular tissues, and may be superior to oral propranolol in the treatment of periocular capillary hemangiomas. The objective of this study was to investigate the effects of dosing protocol on the distribution of propranolol in the periocular tissues and plasma after topical ocular instillation.

METHODS

Each rabbit received propranolol 0.5% ophthalmic solution using one of the following dosing protocols: three drops of 50 μL, one drop of 50 μL, or one drop of 25 μL. The periocular tissues (e.g. eyelids and extraocular muscles) and blood were collected and assayed for propranolol at 1 h after dosing.

RESULTS

Decreasing the concentration of eye drops (1% to 0.5%), decreasing the number of eye drops during dosing (three drops to one drop), or decreasing the instilled volume (50 µL to 25 µL) generally lowered the concentration of propranolol in the periocular tissues. Nevertheless, therapeutic levels of propranolol (> 0.4 μg/g) were delivered to the periocular tissues at 1 h after dosing using any of the three protocols examined. Dose-dependent concentrations in some periocular tissues and plasma were observed over the dose range of 0.125 mg to 1.5 mg. The plasma concentration of propranolol was not measurable when a single 25 μL of propranolol 0.5% was instilled in the eye.

CONCLUSIONS

The dosing protocol of topical ocular instillation can be tailored to achieve the desired therapeutic concentrations of propranolol in the periocular tissues while minimizing systemic exposure.

pH-responsive polymer-drug conjugates as multifunctional micelles for cancer-drug delivery

We developed a novel linear pH-sensitive conjugate methoxy poly(ethylene glycol)-4β-aminopodophyllotoxin (mPEG-NPOD-I) by a covalently linked 4β-aminopodophyllotoxin (NPOD) and PEG via imine bond, which was amphiphilic and self-assembled to micelles in an aqueous solution. The mPEG-NPOD-I micelles simultaneously served as an anticancer drug conjugate and as drug carriers. As a drug conjugate, mPEG-NPOD-I showed a significantly faster NPOD release at a mildly acidic pH of 5.0 and 4.0 than a physiological pH of 7.4. Notably, it was confirmed that this drug conjugate could efficiently deliver NPOD to the nuclei of the tumor cells and led to much more cytotoxic effects to A549, Hela, and HepG2 cancer cells than the parent NPOD. The half maximal inhibitory concentration (IC₅₀) of mPEG-NPOD-I was about one order magnitude lower than that of the NPOD. In vivo, mPEG-NPOD-I reduced the size of the tumors significantly, and the biodistribution studies indicated that this drug conjugate could selectively accumulate in tumor tissues. As drug carriers, the mPEG-NPOD-I micelles encapsulated hydrophobic PTX with drug-loading efficiencies of 57% and drug-loading content of 16%. The loaded PTX also showed pH-triggered fast release behavior, and good additive cytotoxicity effect was observed for the PEG-NPOD-I/PTX. We are convinced that these multifunctional drug conjugate micelles have tremendous potential for targeted cancer therapy.

Terahertz science and technology of carbon nanomaterials

The diverse applications of terahertz (THz) radiation and its importance to fundamental science makes finding ways to generate, manipulate and detect THz radiation one of the key areas of modern applied physics. One approach is to utilize carbon nanomaterials, in particular, single-wall carbon nanotubes and graphene. Their novel optical and electronic properties offer much promise to the field of THz science and technology. This article describes the past, current, and future of THz science and technology of carbon nanotubes and graphene. We will review fundamental studies such as THz dynamic conductivity, THz nonlinearities and ultrafast carrier dynamics as well as THz applications such as THz sources, detectors, modulators, antennas and polarizers.

Synthesis and surface immobilization of antibacterial hybrid silver-poly(l-lactide) nanoparticles

Infections associated with medical devices are a substantial healthcare problem. Consequently, there has been increasing research and technological efforts directed toward the development of coatings that are capable of preventing bacterial colonization of the device surface. Herein, we report on novel hybrid silver loaded poly(L-lactic acid) nanoparticles (PLLA-AgNPs) with narrowly distributed sizes (17 ± 3 nm) prepared using a combination of solvent evaporation and mini-emulsion technology. These particles were then immobilized onto solid surfaces premodified with a thin layer of allylamine plasma polymer (AApp). The antibacterial efficacy of the PLLA-AgNPs nanoparticles was studied in vitro against both gram-positive (Staphylococcus epidermidis) and gram-negative (Escherichia coli) bacteria. The minimal inhibitory concentration values against Staphylococcus epidermidis and Escherichia coli were 0.610 and 1.156 μg · mL(-1), respectively. The capacity of the prepared coatings to prevent bacterial surface colonization was assessed in the presence of Staphylococcus epidermidis, which is a strong biofilm former that causes substantial problems with medical device associated infections. The level of inhibition of bacterial growth was 98%. The substrate independent nature and the high antibacterial efficacy of coatings presented in this study may offer new alternatives for antibacterial coatings for medical devices.

Biological characterization of cetuximab-conjugated gold nanoparticles in a tumor animal model

Gold nanoparticles (AuNPs) are widely applied to the diagnosis and treatment of cancer and can be modified to contain target-specific ligands via gold-thiolate bonding. This study investigated the pharmacokinetics and microdistribution of antibody-mediated active targeting gold nanoparticles in mice with subcutaneous lung carcinoma. We conjugated AuNPs with cetuximab (C225), an antibody-targeting epidermal growth factor receptor (EGFR), and then labeled with In-111, which created EGFR-targeted AuNPs. In vitro studies showed that after a 2 h incubation, the uptake of C225-conjugated AuNPs in high EGFR-expression A549 cells was 14.9-fold higher than that of PEGylated AuNPs; furthermore, uptake was also higher at 3.8-fold when MCF7 cells with lower EGFR-expression were used. MicroSPECT/CT imaging and a biodistribution study conducted by using a A549 tumor xenograft mouse model provided evidence of elevated uptake of the C225-conjugated AuNPs into the tumor cells as a result of active targeting. Moreover, the microdistribution of PEGylated AuNPs revealed that a large portion of AuNPs remained in the tumor interstitium, whereas the C225-conjugated AuNPs displayed enhanced internalization via antibody-mediated endocytosis. Our findings suggest that the anti-EGFR antibody-conjugated AuNPs are likely to be a plausible nano-sized vehicle for drug delivery to EGFR-expressing tumors.