Anticancer activity of mycobacterial DNA: effect of formulation as chitosan nanoparticles

Facile preparation of toluidine blue-loaded DNA nanogels for anticancer photodynamic therapy

Photodynamic therapy (PDT) provides an effective therapeutic option for different types of cancer in addition to surgery, radiation, and chemotherapy. The treatment outcome of PDT is largely determined by both the light and dark toxicity of photosensitizers (PSs), which can be technically improved with the assistance of a drug delivery system, especially the nanocarriers. Toluidine blue (TB) is a representative PS that demonstrates high PDT efficacy; however, its application is largely limited by the associated dark toxicity. Inspired by TB's noncovalent binding with nucleic acids, in this study, we demonstrated that DNA nanogel (NG) could serve as an effective TB delivery vehicle to facilitate anticancer PDT. The DNA/TB NG was constructed by the simple self-assembly between TB and short DNA segments using cisplatin as a crosslinker. Compared with TB alone, DNA/TB NG displayed a controlled TB-releasing behavior, effective cellular uptake, and phototoxicity while reducing the dark toxicity in breast cancer cells MCF-7. This DNA/TB NG represented a promising strategy to improve TB-mediated PDT for cancer treatments.

Microenvironmental Control of MUC1 Aptamer-Guided Acid-Labile Nanoconjugate within Injectable Microporous Hydrogels

Although aptamers are well-known as cell-specific membrane biomarkers for tumor-targeted therapy, it is important to avoid their degradation by nucleases in vivo. In this study, we developed a MUC1 aptamer-doxorubicin nanoconjugate (APT-DOX) through an acid-labile linkage and embedded APT-DOX into a thermosensitive hydrogel for antitumor therapy. The hydrogels exhibit a sol-gel transition upon intratumoral injection, resulting in the protection and controlled release control of APT-DOX with the shielding of the gel network. Moreover, the released APT-DOX was prone to be enriched at the tumor cells due to specific intracellular transport by the overexpressing MUC1 protein; however, APT-DOX regained the free DOX form via the rupture of the linkage under tumor cells lysosome acidic conditions and achieved increased concentration in the nucleus for antitumor treatment.

Controlling DNA-nanoparticle serum interactions

Understanding the interaction of molecularly assembled nanoparticles with physiological fluids is critical to their use for in vivo delivery of drugs and contrast agents. Here, we systematically investigated the factors and mechanisms that govern the degradation of DNA on the nanoparticle surface in serum. We discovered that a higher DNA density, shorter oligonucleotides, and thicker PEG layer increased protection of DNA against serum degradation. Oligonucleotides on the surface of nanoparticles were highly resistant to DNase I endonucleases, and degradation was carried out exclusively by protein-mediated exonuclease cleavage and full-strand desorption. These results enabled the programming of the degradation rates of the DNA-assembled nanoparticle system from 0.1 to 0.7 h^-1 and the engineering of superstructures that can release two different preloaded dye molecules with distinct kinetics and half-lives ranging from 3.3 to 9.8 h. This study provides a general framework for investigating the serum stability of DNA-containing nanostructures. The results advance our understanding of engineering principles for designing nanoparticle assemblies with controlled in vivo behavior and present a strategy for storage and multistage release of drugs and contrast agents that can facilitate the diagnosis and treatment of cancer and other diseases.

A study on biochemical changes during cultivation of Rhizopus oryzae in deproteinized whey medium in relation to chitosan production

The kinetics of cultivation of zygomycete filamentous fungus Rhizopus oryzae in deproteinized whey medium in relation to chitosan production was studied here to optimize chitosan production from R. oryzae as well as utilize whey, a by-product of sweetmeat industry as a cheap source of sugar in the cultivation process. Chitosan content of R. oryzae biomass was found to be increased with time during cultivation and reached maximum (13·6%) after 72 h and then declined steadily. Maximum 1·13 g of chitosan was obtained from one litre of deproteinized whey medium. Concentration of lactose in the medium was observed to be reduced from 45·0 to 11·7 g l(-1) during cultivation resulting in decrease in biochemical oxygen demand (BOD) of whey by approx. 60%, and this was important from environmental point of view before discharging whey into any water body. However, no significant change in pH or titratable acidity was noted during the entire course of cultivation, probably due to good buffering capacity of the medium. Molecular weight of chitosan varied from 130 to 230 kDa depending on the time of cultivation, but no significant change in degree of deacetylation of chitosan (approx. 87%) was found during cultivation.

SIGNIFICANCE AND IMPACT OF THE STUDY

Whey is the largest by-product of dairy industries, and its disposal is a big environmental issue because of its high biological oxygen demand (BOD) value. This study will help to lower BOD value of whey by using it as a cultivation medium for fungus R. oryzae that contains chitosan, a very commercially important material on its cell wall. Moreover, the study on biochemical changes in whey during cultivation process with R. oryzae will help to understand the exact changes occurring in the medium and optimize cultivation process to isolate chitosan in larger extent with better and uniform physicochemical properties.

Pulmonary delivery of inhalable nanoparticles: dry powder inhalers

Pulmonary administration of inhalable nanoparticles (NPs) is an emerging area of interest. Dry powder inhalers may offer particular advantages for pulmonary administration of NPs. This article reviews research performed on the formulation of inhalable NPs as dry powder to achieve deep-lung deposition and enhance NP redispersibility. Moreover, the article summarizes up-to-date in vivo applications of inhalable NPs as dry powder inhalers.

Biodegradable nano-micro carrier systems for sustained pulmonary drug delivery: (I) self-assembled nanoparticles encapsulated in respirable/swellable semi-IPN microspheres

Design of appropriate inhaled carriers with adequate aerodynamic properties, drug release, biodegradation and evasion of macrophage uptake is a major challenge for controlled release pulmonary drug delivery. In this study, PEG graft copolymerized onto N-phthaloyl chitosan (NPHCs) was synthesized then characterized using FTIR, EA, DSC and 2D-XRD. The resulting PEG-g-NPHCs copolymers were self-assembled into drug-loaded nanoparticles and encapsulated in respirable/swellable sodium alginate semi-IPN hydrogel microspheres as novel biodegradable carriers for controlled release pulmonary drug delivery. The developed nano-/microspheres carrier systems were formed via spray drying followed by ionotropic crosslinking in mild aqueous medium. The size of the developed self-assembled nanoparticles and the microspheres was measured using dynamic light scattering and laser diffraction, respectively. Morphology, moisture content, in vitro biodegradation and dynamic swelling studies were also investigated for the developed carriers. A model protein was entrapped and the in vitro release profiles were determined in PBS, pH 7.4 at 37 degrees C. A dry powder aerosolization study was conducted using a Next Generation Impactor (NGI). The developed microspheres had suitable aerodynamic diameters (1.02-2.63 microm) and an excellent fine particle fraction, FPF of 31.52%. The microspheres showed also a very fast initial swelling within the first 2 min and started to enzymatically degrade within the first 2h. Moreover, the microspheres entrapped up 90% of the model drug and showed promising in vitro sustained release profiles as compared to the control formulation.

Nonviral delivery of cancer genetic vaccines

The potential use of genetic vaccines to address numerous diseases including cancer is promising, but currently unrealized. Here, we review advances in the nonviral delivery of antigen-encoded plasmid DNA for the purpose of treating cancer through the human immune system, as this disease has drawn the most attention in this field to date. Brief overviews of dendritic cell immunobiology and the mechanism of immune activation through genetic vaccines set the stage for the desirability of delivery technology. Several promising nonviral delivery techniques are discussed along with a mention of targeting strategies aimed at improving the potency of vaccine formulations. Implications for the future of genetic vaccines are also presented.

Adsorption Kinetics and Thermodynamics of Acid Dyes on a Carboxymethylated Chitosan-Conjugated Magnetic Nano-Adsorbent

The monodisperse chitosan-conjugated Fe(3)O(4) nanoparticles with a mean diameter of 13.5 nm were fabricated by the carboxymethylation of chitosan and its covalent binding onto Fe(3)O(4) nanoparticles via carbodiimide activation. The carboxymethylated chitosan (CMCH)-conjugated Fe(3)O(4) nanoparticles with about 4.92 wt.-% of CMCH had an isoelectric point of 5.95 and were shown to be quite efficient as anionic magnetic nano-adsorbent for the removal of acid dyes. Both the adsorption capacities of crocein orange G (AO12) and acid green 25 (AG25), as the model compounds, decreased with increasing pH, and the decreasing effect was more significant for AO12. On the contrary, the increase in the ionic strength decreased the adsorption capacity of AG25 but did not affect, obviously, the adsorption capacity of AO12. By the addition of NaCl and NaOH, both AO12 and AG25 could desorb and their different desorption behavior could be attributed to the combined effect of pH and ionic strength. From the adsorption kinetics and thermodynamics studies, it was found that both the adsorption processes of AO12 and AG25 obeyed the pseudo-second-order kinetic model, Langmuir isotherm, and might be surface reaction-controlled. Furthermore, the time required to reach the equilibrium for each one was significantly shorter than those using the micro-sized adsorbents due to the large available surface area. Also, based on the weight of chitosan, the maximum adsorption capacities were 1 883 and 1 471 mg x g(-1) for AO12 and AG25, respectively, much higher than the reported data. Thus, the anionic magnetic nano-adsorbent could not only be magnetically manipulated but also possessed the advantages of fast adsorption rate and high adsorption capacity. This could be useful in the fields of separation and magnetic carriers. [formula in text].

Preparation and adsorption properties of monodisperse chitosan-bound Fe3O4 magnetic nanoparticles for removal of Cu(II) ions

Monodisperse chitosan-bound Fe(3)O(4) nanoparticles were developed as a novel magnetic nano-adsorbent for the removal of heavy metal ions. Chitosan was first carboxymethylated and then covalently bound on the surface of Fe(3)O(4) nanoparticles via carbodiimide activation. Transmission electron microscopy micrographs showed that the chitosan-bound Fe(3)O(4) nanoparticles were monodisperse and had a mean diameter of 13.5 nm. X-ray diffraction patterns indicated that the magnetic nanoparticles were pure Fe(3)O(4) with a spinel structure, and the binding of chitosan did not result in a phase change. The binding of chitosan was also demonstrated by the measurement of zeta potential, and the weight percentage of chitosan bound to Fe(3)O(4) nanoparticles was estimated to be about 4.92 wt%. The chitosan-bound Fe(3)O(4) nanoparticles were shown to be quite efficient for the removal of Cu(II) ions at pH>2. In particular, the adsorption rate was so fast that the equilibrium was achieved within 1 min due to the absence of internal diffusion resistance. The adsorption data obeyed the Langmuir equation with a maximum adsorption capacity of 21.5 mg g(-1) and a Langmuir adsorption equilibrium constant of 0.0165 L mg(-1). The pH and temperature effects revealed that the adsorption capacity increased significantly with increasing pH at pH 2-5, and the adsorption process was exothermic in nature with an enthalpy change of -6.14 kJ mol(-1) at 300-330 K.

Trojan particles: large porous carriers of nanoparticles for drug delivery

We have combined the drug release and delivery potential of nanoparticle (NP) systems with the ease of flow, processing, and aerosolization potential of large porous particle (LPP) systems by spray drying solutions of polymeric and nonpolymeric NPs into extremely thin-walled macroscale structures. These hybrid LPPs exhibit much better flow and aerosolization properties than the NPs; yet, unlike the LPPs, which dissolve in physiological conditions to produce molecular constituents, the hybrid LPPs dissolve to produce NPs, with the drug release and delivery advantages associated with NP delivery systems. Formation of the large porous NP (LPNP) aggregates occurs via a spray-drying process that ensures the drying time of the sprayed droplet is sufficiently shorter than the characteristic time for redistribution of NPs by diffusion within the drying droplet, implying a local Peclet number much greater than unity. Additional control over LPNPs physical characteristics is achieved by adding other components to the spray-dried solutions, including sugars, lipids, polymers, and proteins. The ability to produce LPNPs appears to be largely independent of molecular component type as well as the size or chemical nature of the NPs.