Magnetic PECA nanoparticles as drug carriers for targeted delivery: Synthesis and release characteristics

Targeted delivery of silibinin via magnetic niosomal nanoparticles: potential application in treatment of colon cancer cells

Introduction: In recent years, various nanoparticles (NPs) have been discovered and synthesized for the targeted therapy of cancer cells. Targeted delivery increases the local concentration of therapeutics and minimizes side effects. Therefore, NPs-mediated targeted drug delivery systems have become a promising approach for the treatment of various cancers. As a result, in the current study, we aimed to design silibinin-loaded magnetic niosomes nanoparticles (MNNPs) and investigate their cytotoxicity property in colorectal cancer cell treatment. Methods: MNPs ferrofluids were prepared and encapsulated into niosomes (NIOs) by the thin film hydration method. Afterward, the morphology, size, and chemical structure of the synthesized MNNPs were evaluated using the TEM, DLS, and FT-IR techniques, respectively. Results and Discussion: The distribution number of MNNPs was obtained at about 50 nm and 70 nm with a surface charge of -19.0 mV by TEM and DLS analysis, respectively. Silibinin loading efficiency in NIOs was about 90%, and the drug release pattern showed a controlled release with a maximum amount of about 49% and 70%, within 4 h in pH = 7.4 and pH = 5.8, respectively. To investigate the cytotoxicity effect, HT-29 cells were treated with the various concentration of the drugs for 24 and 48 h and evaluated by the MTT as well as flow cytometry assays. Obtained results demonstrated promoted cell cytotoxicity of silibinin-loaded MNNPs (5-fold decrease in cell viability) compared to pure silibinin (3-fold decrease in cell viability) while had no significant cytotoxic effect on HEK-293 (normal cell line) cells, and the cellular uptake level of MNNPs by the HT-29 cell line was enhanced compared to the control group. In conclusion, silibinin-loaded MNNPs complex can be considered as an efficient treatment approach for colorectal cancer cells.

Metal and Metal Oxides Nanoparticles and Nanosystems in Anticancer and Antiviral Theragnostic Agents

The development of antiviral treatment and anticancer theragnostic agents in recent decades has been associated with nanotechnologies, and primarily with inorganic nanoparticles (INPs) of metal and metal oxides. The large specific surface area and its high activity make it easy to functionalize INPs with various coatings (to increase their stability and reduce toxicity), specific agents (allowing retention of INPs in the affected organ or tissue), and drug molecules (for antitumor and antiviral therapy). The ability of magnetic nanoparticles (MNPs) of iron oxides and ferrites to enhance proton relaxation in specific tissues and serve as magnetic resonance imaging contrast agents is one of the most promising applications of nanomedicine. Activation of MNPs during hyperthermia by an external alternating magnetic field is a promising method for targeted cancer therapy. As therapeutic tools, INPs are promising carriers for targeted delivery of pharmaceuticals (either anticancer or antiviral) via magnetic drug targeting (in case of MNPs), passive or active (by attaching high affinity ligands) targeting. The plasmonic properties of Au nanoparticles (NPs) and their application for plasmonic photothermal and photodynamic therapies have been extensively explored recently in tumor treatment. The Ag NPs alone and in combination with antiviral medicines reveal new possibilities in antiviral therapy. The prospects and possibilities of INPs in relation to magnetic hyperthermia, plasmonic photothermal and photodynamic therapies, magnetic resonance imaging, targeted delivery in the framework of antitumor theragnostic and antiviral therapy are presented in this review.

Two cationic iron-based crystalline porous materials for encapsulation and sustained release of 5-fluorouracil

Iron-based crystalline porous materials (CPMs) emerged as a new class of biodegradable and non-toxic materials of high interest for drug delivery systems (DDSs) due to their high loading capacity and controllable structures. This work constructed two kinds of Fe-CPM coordination polymers (CPM-83 and CPM-85) from typical oxo-centered trimers of the iron octahedra cluster [Fe₃O(RCOO)₃(TPT)] with two functional modules. The tri-topic pyridine ligand (TPT) occupied the open metal sites of the trinuclear cluster, precluding the attachment of neutralizing anions, leading to three-dimensional frameworks with a positive charge and higher stability. Moreover, the triazine ligand TPT divides the original columnar channel into small domains, improving the adsorption efficiency and maximizing the host-guest interaction. Hence, the suitable pore size and electrostatic force make the materials highly adsorption selective for the anticancer drug 5-fluorouracil (5-Fu). We show that Fe-CPM-83 and Fe-CPM-85 loaded with 5-Fu are efficient drug delivery vehicles with loading content as high as 60.5 (wt%) and 32.8 (wt%) within 2-5 h of loading time. Simultaneously, their sustained release kinetics can be up to 96 hours with a completely different pH-responsive controlled release. The released content is 77% or 85% for each complex, significantly prolonging the release process and decreasing the plasma concentration. The MTT assay was performed on mouse fibroblasts (L929) to demonstrate the satisfactory biocompatibility of the matrix. This work has momentous research significance and application value for developing novel drug-delivery materials.

UV-Blocking, Transparent, and Antioxidant Polycyanoacrylate Films

Applications of cyanoacrylate monomers are generally limited to adhesives/glues (instant or superglues) and forensic sciences. They tend to polymerize rapidly into rigid structures when exposed to trace amounts of moisture. Transforming cyanoacrylate monomers into transparent polymeric films or coatings can open up several new applications, as they are biocompatible, biodegradable and have surgical uses. Like other acrylics, cyanoacrylate polymers are glassy and rigid. To circumvent this, we prepared transparent cyanoacrylate films by solvent casting from a readily biodegrade solvent, cyclopentanone. To improve the ductility of the films, poly(propylene carbonate) (PPC) biopolymer was used as an additive (maximum 5 wt.%) while maintaining transparency. Additionally, ductile films were functionalized with caffeic acid (maximum 2 wt.%), with no loss of transparency while establishing highly effective double functionality, i.e., antioxidant effect and effective UV-absorbing capability. Less than 25 mg antioxidant caffeic acid release per gram film was achieved within a 24-h period, conforming to food safety regulations. Within 2 h, films achieved 100% radical inhibition levels. Films displayed zero UVC (100–280 nm) and UVB (280–315 nm), and ~15% UVA (315–400 nm) radiation transmittance comparable to advanced sunscreen materials containing ZnO nanoparticles or quantum dots. Transparent films also exhibited promising water vapor and oxygen barrier properties, outperforming low-density polyethylene (LPDE) films. Several potential applications can be envisioned such as films for fatty food preservation, biofilms for sun screening, and biomedical films for free-radical inhibition.

Novel synthesis of platinum complexes and their intracellular delivery to tumor cells by means of magnetic nanoparticles

Platinum-based drugs are popular in clinics as chemotherapeutic agents to treat solid tumors. However, severe side effects such as nephro- and neurotoxicity impose strict dosage limitations that can lead to the development of drug resistance and tumor relapse. To overcome these issues Pt(iv) prodrugs and platinum delivery systems might represent the next generation of platinum-based drugs. In this study four novel Pt(ii) complexes (namely, PEG-Glu-Pt-EDA, PEG-Glu-Pt-DACH, PEG-Mal-Pt-EDA and PEG-Mal-Pt-DACH) were synthesized and a general strategy to covalently bind them to iron oxide nanoparticles was developed. The intracellular uptake and cell distribution studies of Pt-tethered magnetic nanoparticles on breast and ovarian cancer cell line models indicate that binding of the Pt complexes to the nanoparticles facilitates, for all the complexes, cellular internalization. Moreover, the magnetic nanoparticles (MNPs), as shown in a magnetofection experiment, enhance the uptake of MNP-Pt conjugates if a magnet is placed beneath the culture dish of tumor cells. As shown by a Pt release experiment, intranuclear platinum quantification and TEM analysis on cell sections, the presence of a pH-sensitive dicarboxylic group coordinating the Pt complex, triggers platinum dissociation from the NP surface. In addition, the triazole moiety facilitates endosomal swelling and the leakage of platinum from the endosomes with intranuclear localization of platinum release by the NPs. Finally, as assessed by MTT, caspase, calcein/ethidium bromide live/dead assays, among the four NP-Pt conjugates, the NP-Glu-Pt-EDA complex having a glutamate ring and ethylenediamine as a chelating amine group of the platinum showed higher cytotoxicity than the other three MNP-platinum conjugates.

The Potential of Magnetic Nanoparticles for Diagnosis and Treatment of Cancer Based on Body Magnetic Field and Organ-on-the-Chip

Cancer is an abnormal cell growth which tends to proliferate in an uncontrolled way and, in some cases, leads to metastasis. If cancer is left untreated, it can immediately cause death. The use of magnetic nanoparticles (MNPs) as a drug delivery system will enable drugs to target tissues and cell types precisely. This study describes usual strategies and consideration for the synthesis of MNPs and incorporates payload drug on MNPs. They have advantages such as visual targeting and delivering which will be discussed in this review. In addition, we considered body magnetic field to make drug delivery process more effective and safer by the application of MNPs and tumor-on-chip.

Magnetic Nanomaterials for Magnetically-Aided Drug Delivery and Hyperthermia

Magnetic nanoparticles have continuously gained importance for the purpose of magnetically-aided drug-delivery, magnetofection, and hyperthermia. We have summarized significant experimental approaches, as well as their advantages and disadvantages with respect to future clinical translation. This field is alive and well and promises meaningful contributions to the development of novel cancer therapies.

Highly Transparent Polyethylcyanoacrylates from Approved Eco-Friendly Fragrance Materials Demonstrating Excellent Fog-Harvesting and Anti-Wear Properties

Superglue monomers belong to a family of cyanoacrylates that are known for their very rapid polymerization upon contact with moist surfaces. Their biodegradation and low toxicity make them attractive as medical and veterinary adhesives. Although the fast-acting polymerization characteristics have been successfully utilized to design nanoscale polymeric particles that can carry drugs or other inorganic nanoparticles, it constitutes a significant drawback if one desires to produce other forms of functional biodegradable acrylics, such as coatings, sheets, or nanocomposites. This is because rapid polymerization in air creates highly porous and brittle structures. Here, we address this drawback by reporting a simple and inexpensive method of fabricating highly transparent (>92%) polyethylcyanoacrylate (PECA) coatings by dispersing the monomer in a fragrance-classified green liquid, cyclopentanone. The resulting transparent coatings were hydrophilic but with slippery wetting characteristics, suitable as efficient fog-harvesting templates. Furthermore, another fragrance liquid, benzyl alcohol, is introduced as a plasticizer and co-solvent to overcome its brittleness while retaining its transparency. The same plasticized monomer solutions, dispersing low concentrations of graphene (<0.5 wt %), were allowed to self-assemble on stainless steel surfaces, forming low-friction and anti-wear dry lubricants by decreasing the steel friction coefficient and wear rate by 6- and 10-fold, respectively.

Drug Delivery Strategies for Platinum-Based Chemotherapy

Few chemotherapeutics have had such an impact on cancer management as cis-diamminedichloridoplatinum(II) (CDDP), also known as cisplatin. The first member of the platinum-based drug family, CDDP's potent toxicity in disrupting DNA replication has led to its widespread use in multidrug therapies, with particular benefit in patients with testicular cancers. However, CDDP also produces significant side effects that limit the maximum systemic dose. Various strategies have been developed to address this challenge including encapsulation within micro- or nanocarriers and the use of external stimuli such as ultrasound to promote uptake and release. The aim of this review is to look at these strategies and recent scientific and clinical developments.

Nanomaterials as nanocarriers: a critical assessment why these are multi-chore vanquisher in breast cancer treatment

Breast cancer is a group of diseases with various subtypes and leads to high mortality throughout the globe. Various conventional techniques are in practice to cure breast cancer but these techniques are linked with various shortcomings. Mostly these treatments are not site directed and cause toxicity towards normal cells. In order to overcome these issues, we need smart system that can deliver anticancer drugs to specific sites. Targeted drug delivery can be achieved via passive or active drug delivery using nanocarriers. This mode of drug delivery is more effective against breast cancer and may help in the reduction of mortality rate. Potentially used nanocarriers for targeted drug delivery belong to organic and inorganic molecules. Various FDA approved nano products are in use to cure breast cancer. However, body's defense system is main limitation for potential use of nano systems. However, this can be overcome by surface modification of nanocarriers. In this review, breast cancer and its types, targeted drug delivery and nanocarriers used to cure breast cancer are discussed. By progressing nanotechnology, we will be able to fight against this life threatening issue and serve the humanity, which is the basic aim of scientific knowledge.

Core–Shell γ-Fe2O3/SiO2/PCA/Ag-NPs Hybrid Nanomaterials as a New Candidate for Future Cancer Therapy

In the current study, γ- Fe 2 O 3/ SiO 2/ PCA / Ag -NPs hybrid nanomaterials were successfully synthesized and characterized. At first, prepared γ- Fe 2 O 3 core nanoparticles were modified by SiO 2 layer. Then they were covered by poly citric acid (PCA) via melting esterification method as well. PCA shell acts as an effective linker, and provides vacancies for conveying drugs. Moreover, this shell as an effective capping agent directs synthesis of silver nanoparticles ( Ag -NPs) via in situ photo-reduction of silver ions by sunlight-UV irradiation. This system has several benefits as a suitable cancer therapy nanomaterial. Magnetic nanoparticles (MNPs) can guide Ag -NPs and drugs to cancer cells and then Ag -NPs can affect those cells via Ag -NPs anti-angiogenesis effect. Size and structure of the prepared magnetic hybrid nanomaterials were characterized using FTIR and UV-Vis spectra, AFM and TEM pictures and XRD data.

4-aminobenzoic acid-coated maghemite nanoparticles as potential anticancer drug magnetic carriers: a case study on highly cytotoxic Cisplatin-like complexes involving 7-azaindoles

This study describes a one-pot synthesis of superparamagnetic maghemite-based 4-aminobenzoic acid-coated spherical core-shell nanoparticles (PABA@FeNPs) as suitable nanocomposites potentially usable as magnetic carriers for drug delivery. The PABA@FeNPs system was subsequently functionalized by the activated species (1* and 2*) of highly in vitro cytotoxic cis-[PtCl2(3Claza)2] (1; 3Claza stands for 3-chloro-7-azaindole) or cis-[PtCl2(5Braza)2] (2; 5Braza stands for 5-bromo-7-azaindole), which were prepared by a silver(I) ion assisted dechlorination of the parent dichlorido complexes. The products 1*@PABA@FeNPs and 2*@PABA@FeNPs, as well as an intermediate PABA@FeNPs, were characterized by a combination of various techniques, such as Mössbauer, FTIR and EDS spectroscopy, thermal analysis, SEM and TEM. The results showed that the products consist of well-dispersed maghemite-based nanoparticles of 13 nm average size that represent an easily obtainable system for delivery of highly cytotoxic cisplatin-like complexes in oncological practice.

Controlled release of lidocaine hydrochloride from polymerized drug-based deep-eutectic solvents

This work takes advantage of the transformation of lidocaine hydrochloride into deep-eutectic solvents (DESs) – ionic liquid analogues – to incorporate polymerizable counterparts into DESs, such that polymer–drug complexes are synthesized by free-radical frontal polymerization without the use of a solvent.

Self-assembling, amphiphilic polymer-gemcitabine conjugate shows enhanced antitumor efficacy against human pancreatic adenocarcinoma

The therapeutic efficacy of gemcitabine is severely compromised due to its rapid plasma metabolism. Moreover, its hydrophilicity poses a challenge for its efficient entrapment in nanosized delivery systems and to provide a sustained release profile. In this study, gemcitabine was covalently conjugated to poly(ethylene glycol)-block-poly(2-methyl-2-carboxyl-propylene carbonate) (PEG-PCC) which could self-assemble into micelles of 23.6 nm. These micelles afforded protection to gemcitabine from plasma metabolism as evident by negligible amount of gemcitabine and its metabolite dFdU detected in the plasma after 24 h. A controlled release of gemcitabine from the micelles was observed with 53.89% drug release in 10 days in the presence of protease enzyme Cathepsin B. Gemcitabine conjugated micelles were cytotoxic, showed internalization, and induced cell apoptosis in MIA PaCa-2 and L3.6pl pancreatic cancer cell lines. These micelles efficiently inhibited tumor growth when injected intravenously into MIA PaCa-2 cell derived xenograft tumor bearing NSG mice at a dose of 40 mg/kg in terms of reduced tumor volume and tumor weight (0.38 g vs 0.58 g). TUNEL assay revealed that gemcitabine conjugated micelles induced a much higher extent of apoptosis in the tumor tissues compared to free gemcitabine. In conclusion, gemcitabine conjugated micelles were able to enhance the drug payload, protect it from rapid plasma metabolism, and provide a sustained release and showed enhanced antitumor activity, and thus have the potential to provide a better therapeutic alternative for treating pancreatic cancer.

Biological applications of magnetic nanoparticles

In this review an overview about biological applications of magnetic colloidal nanoparticles will be given, which comprises their synthesis, characterization, and in vitro and in vivo applications. The potential future role of magnetic nanoparticles compared to other functional nanoparticles will be discussed by highlighting the possibility of integration with other nanostructures and with existing biotechnology as well as by pointing out the specific properties of magnetic colloids. Current limitations in the fabrication process and issues related with the outcome of the particles in the body will be also pointed out in order to address the remaining challenges for an extended application of magnetic nanoparticles in medicine.

Composite polymeric magnetic nanoparticles for co-delivery of hydrophobic and hydrophilic anticancer drugs and MRI imaging for cancer therapy

Exercising complementary roles of polymer-coated magnetic nanoparticles for precise drug delivery and image contrast agents has attracted significant attention in biomedical applications. The objective of this study was to prepare and characterize magnetic nanoparticles embedded in polylactide-co-glycolide matrixes (PLGA-MNPs) as a dual drug delivery and imaging system capable of encapsulating both hydrophilic and hydrophobic drugs. PLGA-MNPs were capable of encapsulating both hydrophobic and hydrophilic drugs in a 2:1 ratio. Biocompatibility, cellular uptake, cytotoxicity, membrane potential, and apoptosis were carried out in two different cancer cell lines (MCF-7 and PANC-1). The molecular basis of induction of apoptosis was validated by Western blotting analysis. For targeted delivery of drugs, targeting ligand such as Herceptin was used, and such a conjugated system demonstrated enhanced cellular uptake and an augmented synergistic effect in an in vitro system when compared with native drugs. Magnetic resonance imaging was carried out both in vitro and in vivo to assess the efficacy of PLGA-MNPs as contrast agents. PLGA-MNPs showed a better contrast effect than commercial contrast agents due to higher T(2) relaxivity with a blood circulation half-life ∼ 47 min in the rat model. Thus, our results demonstrated the dual usable purpose of formulated PLGA-MNPs toward either, in therapeutics by delivering different hydrophobic or hydrophilic drugs individually or in combination and imaging for cancer therapeutics in the near future.

Application of in situ polymerization for design and development of oral drug delivery systems

Although preformed polymers are commercially available for use in the design and development of drug delivery systems, in situ polymerization has also been employed. In situ polymerization affords the platform to tailor and optimize the drug delivery properties of polymers. This review brings to light the benefits of in situ polymerization for oral drug delivery and the possibilities it provides to overcome the challenges of oral route of administration.

Synthesis and characterization of collagen/hydroxyapatite: magnetite composite material for bone cancer treatment

Our purpose was obtaining and characterizing a complex composite system with multifunctional role: bone graft material and hyperthermia generator necessary for bone cancer therapy. The designed system was a magnetite enriched collagen/hydroxyapatite composite material, obtained by a co-precipitation method. Due to the applied electromagnetic field the magnetite will induce hyperthermia and cause tumoral cell apoptosis. The complex bone graft system was characterised by XRD, FTIR and SEM, while the hyperthermia was quantify by measuring the temperature increase due to the applied alternative electromagnetical field.

Chitosan and glyceryl monooleate nanostructures containing gemcitabine: potential delivery system for pancreatic cancer treatment

The objectives of this study are to enhance cellular accumulation of gemcitabine with chitosan/glyceryl monooleate (GMO) nanostructures, and to provide significant increase in cell death of human pancreatic cancer cells in vitro. The delivery system was prepared by a multiple emulsion solvent evaporation method. The nanostructure topography, size, and surface charge were determined by atomic force microscopy (AFM), and a zetameter. The cellular accumulation, cellular internalization and cytotoxicity of the nanostructures were evaluated by HPLC, confocal microscopy, or MTT assay in Mia PaCa-2 and BxPC-3 cells. The average particle diameter for 2% and 4% (w/w) drug loaded delivery system were 382.3 +/- 28.6 nm, and 385.2 +/- 16.1 nm, respectively with a surface charge of +21.94 +/- 4.37 and +21.23 +/- 1.46 mV. The MTT cytotoxicity dose-response studies revealed the placebo at/or below 1 mg/ml has no effect on MIA PaCa-2 or BxPC-3 cells. The delivery system demonstrated a significant decrease in the IC50 (3 to 4 log unit shift) in cell survival for gemcitabine nanostructures at 72 and 96 h post-treatment when compared with a solution of gemcitabine alone. The nanostructure reported here can be resuspended in an aqueous medium that demonstrate increased effective treatment compared with gemcitabine treatment alone in an in vitro model of human pancreatic cancer. The drug delivery system demonstrates capability to entrap both hydrophilic and hydrophobic compounds to potentially provide an effective treatment option in human pancreatic cancer.

A novel method to prepare magnetite chitosan microspheres conjugated with methotrexate (MTX) for the controlled release of MTX as a magnetic targeting drug delivery system

The purpose of the present study is to develop a new method to prepare magnetite chitosan microspheres conjugated with methotrexate (MTX) for the controlled release of MTX as a magnetic targeting drug delivery system. MTX was first conjugated to the chitosan chain via a peptide bond and then a suspension cross-linking technique was used for the production of magnetic chitosan microspheres with glutaraldehyde as the cross-linker. The MTX-loading capacity of the magnetic chitosan microspheres was determined and drug release experiments were also carried out to discuss the MTX release behavior. All the data support that the magnetic chitosan-MTX microspheres prepared in this method would have great potential application in magnetic targeting drug delivery technology.

Preparation of albumin nanospheres loaded with gemcitabine and their cytotoxicity against BXPC-3 cells in vitro

AIM

To optimize formulation methods for loading gemcitabine (GEM), the main drug against pancreatic cancer, into albumin nanoparticles for extended blood circulation and improved efficacy.

METHODS

GEM was loaded into two sizes of disolvation-crosslinked bovine serum albumin nanoparticles, with a mean diameter of 109.7 nm and 405.6 nm, respectively, by co-precipitation (the direct method) and follow-up adsorption (the indirect method). The antitumor activities of the two nanoparticulate formulations, were evaluated according to their anti-proliferative effects on the human pancreatic cell line BXPC-3, which were assessed using the MTT assay.

RESULTS

The two nanoparticulate formulations, created by direct co-precipitation and indirect adsorption, possessed smooth surfaces and high drug loading efficiencies, 83% and 93% at 11% and 13% drug loading, respectively. The two formulations released GEM for 8 and 12 h, respectively, and significantly improved anti-BXPC-3 proliferation effects, as compared with the GEM solution and the drug-free albumin particles.

CONCLUSION

Co-precipitating and adsorbing GEM into albumin particles resulted in sustained-release nanoparticulate formulations with improved antitumor cytotoxicity. The result suggests that this is a useful formulation strategy for improving the antitumor efficacy of GEM.

Magnetic targeting for site-specific drug delivery: applications and clinical potential

BACKGROUND

Magnetic vehicles are very attractive for delivery of therapeutic agents as they can be targeted to specific locations in the body through the application of a magnetic field gradient. The magnetic localization of a therapeutic agent results in the concentration of the therapy at the target site consequently reducing or eliminating the systemic drug side effects.

OBJECTIVE

The aim of this review is to provide an update on the progress made in the development of the magnetic targeting technique addressing characteristics of the magnetic carriers and limitations of the current targeting magnet systems.

METHODS

This review discusses fundamental requirements for the optimal formulation of the magnetic carrier, current applications and potentially new approaches for the magnetically mediated, site-specific localization of therapeutic agents, including drugs, genes and cells.

RESULTS/CONCLUSION

More efficient targeting magnetic systems in combination with prolonged circulation lifespan and carriers' surface recognition properties will improve the targeting efficiency of magnetic nanocarriers and enhance therapeutic agent availability at the molecular site of agent action. The main future magnetic targeting applications were categorized emphasizing the most promising directions and possible strategies for improving the magnetic targeting technique.

Synthesis and colloidal properties of polyether-magnetite complexes in water and phosphate-buffered saline

Biocompatible magnetic nanoparticles show great promise for many biotechnological applications. This paper addresses the synthesis and characterization of magnetite nanoparticles coated with poly(ethylene oxide) (PEO) homopolymers and amphiphilic poly(propylene oxide-b-ethylene oxide) (PPO-b-PEO) copolymers that were anchored through ammonium ions. Predictions and experimental measurements of the colloidal properties of these nanoparticles in water and phosphate-buffered saline (PBS) as functions of the polymer block lengths and polymer loading are reported. The complexes were found to exist as primary particles at high polymer compositions, and most formed small clusters with equilibrium sizes as the polymer loading was reduced. Through implementation of a polymer brush model, the size distributions from dynamic light scattering (DLS) were compared to those from the model. For complexes that did not cluster, the experimental sizes matched the model well. For complexes that clustered, equilibrium diameters were predicted accurately through an empirical fit derived from DLS data and the half-life for doublet formation calculated using the modified Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. Deviation from this empirical fit provided insight into possible additional interparticle hydrophobic interactions for select complexes for which the DLVO theory could not account. While the polymers remained bound to the nanoparticles in water, most of them desorbed slowly in PBS. Desorption was slowed significantly at high polymer chain densities and with hydrophobic PPO anchor blocks. By tailoring the PPO block length and the number of polymer chains on the surface, flocculation of the magnetite complexes in PBS was avoided. This allows for in vitro experiments where appreciable flocculation or sedimentation will not take place within the specified time scale requirements of an experiment.

Magnetic nanoparticles in MR imaging and drug delivery

Magnetic nanoparticles (MNPs) possess unique magnetic properties and the ability to function at the cellular and molecular level of biological interactions making them an attractive platform as contrast agents for magnetic resonance imaging (MRI) and as carriers for drug delivery. Recent advances in nanotechnology have improved the ability to specifically tailor the features and properties of MNPs for these biomedical applications. To better address specific clinical needs, MNPs with higher magnetic moments, non-fouling surfaces, and increased functionalities are now being developed for applications in the detection, diagnosis, and treatment of malignant tumors, cardiovascular disease, and neurological disease. Through the incorporation of highly specific targeting agents and other functional ligands, such as fluorophores and permeation enhancers, the applicability and efficacy of these MNPs have greatly increased. This review provides a background on applications of MNPs as MR imaging contrast agents and as carriers for drug delivery and an overview of the recent developments in this area of research.

Polymers and nanoparticles: Intelligent tools for intracellular targeting?

In recent years, a new generation of drugs has entered the pharmaceutical market. Some are more potent, but some are also more toxic and thus, therapeutical efficacy may be hindered, and severe side effects may be observed, unless they are delivered to their assigned place of effect. Those targets are not only certain cell types, moreover, in cancer therapy for example, some drugs even have to be targeted to a specific cell organelle. Those targets in eukaryotic cells include among others endo- and lysosomes, mitochondria, the so-called power plants of the cells, and the biggest compartment with almost all the genetic information, the nucleus. In this review, we describe how the drugs can be directed to specific subcellular organelles and focus especially on synthetic polymers and nanoparticles as their carriers. Furthermore, we portray the progress that has been accomplished in recent years in the field of designing the carriers for efficient delivery into these target structures. Yet, we do not fail to mention the obstacles that still exist and are preventing polymeric and nanoparticular drug carrier systems from their broad application in humans.

Nucleoside analogue delivery systems in cancer therapy

Nucleoside analogues (NAs) are important agents in the treatment of hematological malignancies. They are prodrugs that require activation by phosphorylation. Their rapid catabolism, cell resistance and overdistribution in the body jeopardize nucleoside analogue chemotherapy. Accordingly, therapeutic doses of NAs are particularly high and regularly have to be increased, resulting in severe toxicity and narrow therapeutic index. The major challenge is to concentrate the drug at the tumour site, avoiding its distribution to normal tissues. New drug carriers and biomaterials are being developed to overcome some of these obstacles. This review highlights novel NA delivery systems and discusses new technologies that could improve NA cancer therapy.

Magnetic poly epsilon-caprolactone nanoparticles containing Fe3O4 and gemcitabine enhance anti-tumor effect in pancreatic cancer xenograft mouse model

We prepared magnetic (Fe(3)O(4)) poly epsilon-caprolactone (PCL) nanoparticles (mean diameter 164 +/- 3 nm) containing an anticancer drug (gemcitabine) using emulsion-diffusion method in order to develop more efficient drug delivery for cancer treatment. Nanoparticles were smooth, well individualized and homogeneous in size. The values of magnetizations for the magnetic PCL nanoparticles were observed around 10.2 emu/g at 2000 Oe magnetic field intensity and showed super-paramagnetic property. In case of the drug, the drug loading contents was 18.6% and entrapment efficiency was 52.2%. The anti-tumor effects caused by these particles were examined using nude mice bearing subcutaneous human pancreatic adenocarcinoma cells (HPAC) in vivo. We divided that these mice were randomly assigned to one of five treatment groups for experimental contrast. The antitumor effect was showed with 15-fold higher dose when compared to free gemcitabine. From the result, the magnetic PCL nanoparticles may provide a therapeutic benefit by delivering drugs efficiently to magnetically targeted tumor tissues, thus achieving safe and successful anti-tumor effects with low toxicity.

The Korean research & development program on micro-electro-mechanical systems (MEMS) in medical applications

Non or minimally invasive approaches for medical applications are very important for the alleviation of patient complaints. The miniaturization of medical devices using micro & nano technologies might be one of the possible solutions. Several national research and development (R&D) programs have been launched by the Korean government to further the development of biological & medical micro/nano devices in this country. This paper gives an overview of the current status of national R&D programs which are related to the development of micro-electro-mechanical systems (MEMS)/Nano technology in biological and medical applications and discusses the main activities of each program.