Sterile, injectable cyclodextrin nanoparticles: effects of gamma irradiation and autoclaving

Growth-Promoting Gold Nanoparticles Decrease Stress Responses in Arabidopsis Seedlings

The global economic success of man-made nanoscale materials has led to a higher production rate and diversification of emission sources in the environment. For these reasons, novel nanosafety approaches to assess the environmental impact of engineered nanomaterials are required. While studying the potential toxicity of metal nanoparticles (NPs), we realized that gold nanoparticles (AuNPs) have a growth-promoting rather than a stress-inducing effect. In this study we established stable short- and long-term exposition systems for testing plant responses to NPs. Exposure of plants to moderate concentrations of AuNPs resulted in enhanced growth of the plants with longer primary roots, more and longer lateral roots and increased rosette diameter, and reduced oxidative stress responses elicited by the immune-stimulatory PAMP flg22. Our data did not reveal any detrimental effects of AuNPs on plants but clearly showed positive effects on growth, presumably by their protective influence on oxidative stress responses. Differential transcriptomics and proteomics analyses revealed that oxidative stress responses are downregulated whereas growth-promoting genes/proteins are upregulated. These omics datasets after AuNP exposure can now be exploited to study the underlying molecular mechanisms of AuNP-induced growth-promotion.

Insights into Terminal Sterilization Processes of Nanoparticles for Biomedical Applications

Nanoparticles possess a huge potential to be employed in numerous biomedical purposes; their applications may include drug delivery systems, gene therapy, and tissue engineering. However, the in vivo use in biomedical applications requires that nanoparticles exhibit sterility. Thus, diverse sterilization techniques have been developed to remove or destroy microbial contamination. The main sterilization methods include sterile filtration, autoclaving, ionizing radiation, and nonionizing radiation. Nonetheless, the sterilization processes can alter the stability, zeta potential, average particle size, and polydispersity index of diverse types of nanoparticles, depending on their composition. Thus, these methods may produce unwanted effects on the nanoparticles' characteristics, affecting their safety and efficacy. Moreover, each sterilization method possesses advantages and drawbacks; thus, the suitable method's choice depends on diverse factors such as the formulation's characteristics, batch volume, available methods, and desired application. In this article, we describe the current sterilization methods of nanoparticles. Moreover, we discuss the advantages and drawbacks of these methods, pointing out the changes in nanoparticles' biological and physicochemical characteristics after sterilization. Our main objective was to offer a comprehensive overview of terminal sterilization processes of nanoparticles for biomedical applications.

Targeted drug delivery of Methotrexate in situ gels for the treatment of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is considered a debilitating disease that increases the risk of significant morbidity and premature mortality. To circumvent drug-related toxicity and ineffectiveness of anti-inflammatory drugs, there is a significant need for an advanced delivery system that increases bioavailability. The feasibility of in situ gel of methotrexate sodium (MTS) as an effective management for Rheumatoid arthritis was investigated. It was formulated with pluronic F-127 (PLF-127) as primary polymer, hydroxypropyl methylcellulose K4M (HK4M), and polycarbophil (PCL) as a copolymer and characterized by various parameters. The efficacy evaluation by Freund's complete adjuvant (FCA) model, biocompatibility assessment by histopathological studies conducted. The optimized in situ gel (M4) was thermoresponsive, released 93.26 ± 2.39% MTS at 96 hours. In addition, distribution of MTS was even in the optimized sterile and syringeable in situ gel. In vivo studies on wistar rats demonstrated a substantial reduction in paw oedema during the 28-day study period and were biocompatible with the tissues at the injection site. The study was successful in formulating, optimizing MTS in situ gel for effective management of RA.

Nanopharmaceuticals for Eye Administration: Sterilization, Depyrogenation and Clinical Applications

Simple Summary

Nanopharmaceuticals have revolutionized the way ophthalmic drugs are administered to overcome ocular delivery barriers and improve drug bioavailability. The design and production of an efficient ocular drug delivery system still remain a challenge. In this review, we discuss the sterilization and depyrogenation methods, commonly used for ophthalmic nanopharmaceuticals, and their clinical applications.

Abstract

As an immune-privileged target organ, the eyes have important superficial and internal barriers, protecting them from physical and chemical damage from exogenous and/or endogenous origins that would cause injury to visual acuity or even vision loss. These anatomic, physiological and histologic barriers are thus a challenge for drug access and entry into the eye. Novel therapeutic concepts are highly desirable for eye treatment. The design of an efficient ocular drug delivery system still remains a challenge. Although nanotechnology may offer the ability to detect and treat eye diseases, successful treatment approaches are still in demand. The growing interest in nanopharmaceuticals offers the opportunity to improve ophthalmic treatments. Besides their size, which needs to be critically monitored, nanopharmaceuticals for ophthalmic applications have to be produced under sterilized conditions. In this work, we have revised the different sterilization and depyrogenation methods for ophthalmic nanopharmaceuticals with their merits and drawbacks. The paper also describes clinical sterilization of drugs and the outcomes of inappropriate practices, while recent applications of nanopharmaceuticals for ocular drug delivery are also addressed.

Development of PLGA-PEG-COOH and gelatin-based microparticles dual delivery system and E-beam sterilization effects for controlled release of BMP-2 and IGF-1

The purpose of this study was to develop a PLGA-PEG-COOH- and gelatin-based microparticles (MPs) dual delivery system for release of BMP-2 and IGF-1. We made and characterized the delivery system based on its morphology, loading capacity, Encapsulation efficiency and release kinetics. Second, we examined the effects of electron beam (EB) sterilization on BMP-2 and IGF-1 loaded MPs and their biological effects. Third, we evaluated the synergistic effect of a controlled dual release of BMP-2 and IGF-1 on osteogenesis of MSCs. Encapsulation efficiency of growth factors into gelatin and PLGA-PEG-COOH MPs are in the range of 64.78% to 76.11%. E-beam sterilized growth factor delivery systems were effective in significantly promoting osteogenesis of MSCs, although E-beam sterilization decreased the bioactivity of growth factors in MPs by approximately 22%. BMP-2 release behavior from gelatin MPs/PEG hydrogel shows a faster release (52.7%) than that of IGF-1 from the PLGA-PEG-COOH MPs/PEG hydrogel (27.3%). The results demonstrate that the gelatin and PLGA-PEG-COOH MPs based delivery system could realize temporal release of therapeutic biomolecules by incorporating different growth factors into distinct microparticles. EB sterilization was an accessible method for sterilizing growth factors loaded carriers, which could pave the way for implementing growth factor delivery in clinical applications.

Effect of UV and Gamma Irradiation Sterilization Processes in the Properties of Different Polymeric Nanoparticles for Biomedical Applications

The sterilization processes of nanoparticles (NP) by autoclaving and filtration are two of the most utilized methods in the pharmaceutical industry but are not always a viable option. For this reason, the search for alternative options such as UV and gamma radiation is of interest. In this work, we evaluated both types of sterilization on two types of NP in solid state widely employed in the literature for biomedical applications, poly-(ε-caprolactone) and poly(D, L-lactide-co-glycolide) acid NP stabilized with polyvinyl alcohol. Physicochemical properties and cell viability were studied pre- and post-sterilization. The efficiency of irradiation sterilization was performed by a test of sterility using 1 × 10⁸ CFU/mL of Escherichia coli, Staphylococcus aureus, and Candida albicans. Microbiological monitoring revealed that both methods were sufficient for sterilization. After the UV irradiation sterilization (100 µJ/cm²), no substantial changes were observed in the physicochemical properties of the NP or in the interaction or morphology of human glial cells, though 5 and 10 kGy of gamma irradiation showed slight changes of NP size as well as a decrease in cell viability (from 100 µg/mL of NP). At 5 kGy of radiation doses, the presence of trehalose as cryoprotectant reduces the cell damage with high concentrations of NP, but this did not occur at 10 kGy. Therefore, these methods could be highly effective and low-processing-time options for sterilizing NP for medical purposes. However, we suggest validating each NP system because these generally are of different polymer-composition systems.

Carbon nanotubes functionalized with sodium hyaluronate: Sterilization, osteogenic capacity and renal function analysis

AIM

This study determined the optimum gamma irradiation dosage to sterilize sodium hyaluronate (HY), single-walled carbon nanotubes (SWCNT), multi-walled carbon nanotubes (MWCNT) and CNT functionalized with HY (HY-SWCNT and HY-MWCNT), evaluated the structural integrity of the materials and assessed whether sterilized materials kept biological properties without affecting renal function.

MAIN METHODS

Materials were submitted to dosages of 100 gγ to 30 Kgγ and plated onto agar mediums for colony forming units (CFUs) counting. Sterilized samples were inoculated with 10⁷Bacillus clausii, submitted again to gamma irradiation, and plated in agar mediums for CFUs counting. Scanning electron microscope was used for structural evaluation of sterilized materials. Tooth sockets of rats were treated with sterilized materials for bone formation assessment and renal function of the animals was analyzed.

KEY FINDINGS

The optimum gamma dosage for sterilization was 250 gγ for HY and 2.5 Kgγ for the other materials without meaningful structural changes. Sterilized materials significantly increased bone formation (p < 0.05) and they did not compromise renal function and structure.

SIGNIFICANCE

Gamma irradiation efficiently sterilized HY, SWCNT, MWCNT, HY-SWCNT and HY-MWCNT without affecting structural aspects while maintaining their desirable biological properties.

A new alternative for intravenous lipid emulsion 20% w/w from superolein oil and its effect on lipid and liver profiles in an animal model

PURPOSE

Intravenous lipid emulsion (IVLE) was first used to prevent essential fatty acids deficiency. IVLE with α-tocopherol was reported to provide protection against parenteral nutrition-associated liver disease. This study aims to determine the optimal parameters and conditions in developing a physically stable IVLE from superolein palm oil (SoLE 20%) and its effect on lipid and liver profiles in an animal model.

METHODS

SoLE 20% was prepared using superolein oil and MCT oil (1:1), stabilized with egg lecithin and homogenized using a high pressure homogenizer. Mean droplet size was used as the response variable and was measured using laser diffraction and dynamic light scattering method. Physical stability at 4 °C, 25 °C and 40 °C storage temperatures were determined based on particle size and distribution, polydispersity index, zeta potential, viscosity, vitamin E contents and pH. Sterility and pyrogenicity were also investigated. Rabbits were administered with 1.0 g/kg SoLE 20% for 5 h and repeated daily for 3 days to investigate its effect on blood lipid and liver enzymes profile.

RESULTS

SoLE 20% was succesfully prepared using the optimized parameters of 800 psi, 7 cycles and 1.2 g lecithin. The IVLE prepared had a particle size of 252.60 ± 4.88 nm and was physically stable for 4 weeks at different storage temperatures. SoLE 20% had a high content of natural vitamin E, remained sterile and pyrogen free. It was also safe for intravenous administration and did not alter the blood lipid (p > 0.05) and liver enzymes profiles (p > 0.05) of the rabbits.

CONCLUSION

The optimal parameters to develop a stable superolein based IVLE are 800 psi homogenization pressure, 7 homogenization cycles and using 1.2 g lecithin as the emulsifier. SoLE 20% is safe for intravenous administration and does not significantly alter lipid and liver enzymes profiles of the rabbits.

Current developments and applications of microfluidic technology toward clinical translation of nanomedicines

Nanoparticulate drug delivery systems hold great potential for the therapy of many diseases, especially cancer. However, the translation of nanoparticulate drug delivery systems from academic research to industrial and clinical practice has been slow. This slow translation can be ascribed to the high batch-to-batch variations and insufficient production rate of the conventional preparation methods, and the lack of technologies for rapid screening of nanoparticulate drug delivery systems with high correlation to the in vivo tests. These issues can be addressed by the microfluidic technologies. For example, microfluidics can not only produce nanoparticles in a well-controlled, reproducible, and high-throughput manner, but also create 3D environments with continuous flow to mimic the physiological and/or pathological processes. This review provides an overview of the microfluidic devices developed to prepare nanoparticulate drug delivery systems, including drug nanosuspensions, polymer nanoparticles, polyplexes, structured nanoparticles and theranostic nanoparticles. We also highlight the recent advances of microfluidic systems in fabricating the increasingly realistic models of the in vivo milieu for rapid screening of nanoparticles. Overall, the microfluidic technologies offer a promise approach to accelerate the clinical translation of nanoparticulate drug delivery systems.

Nanoformulations for Drug Delivery: Safety, Toxicity, and Efficacy

This chapter presents an outline of the recent available information regarding safety, toxicity, and efficacy of nano drug delivery systems. Of particular importance is the evaluation of several key factors to design nontoxic and effective nanoformulations. Among them, we focus on nanostructure materials and synthesis methods, mechanisms of interactions with biological systems, treatment of nanoparticles, manufacture impurities, and nanostability. Emphasis is given to in silico, in vitro, and in vivo models used to assess and predict the toxicity of these new formulations. Additionally, some examples of in vitro and in vivo studies of specific nanoderivatives are also presented in this chapter.

Production of Isotonic, Sterile, and Kinetically Stable Lipid-Core Nanocapsules for Injectable Administration

Lipid-core nanocapsules (LNC) were designed and prepared as a colloidal system for drug targeting to improve the stability of drugs and allow their controlled release. For parenteral administration, it is necessary to ensure formulation sterility. However, sterilization of nanotechnological devices using an appropriate technique that keeps the supramolecular structure intact remains a challenge. This work aimed to evaluate the effect of autoclaving on the physicochemical characteristics of LNC. Formulations were prepared by the self-assembling method, followed by isotonization and sterilization at varying times and temperatures. The isotonicity was confirmed by determining the freezing temperature, which was -0.51°C. The formulation was broadly characterized, and the diameter of the particles was determined utilizing complementary methods. To evaluate the chemical stability of poly(ε-caprolactone), its molecular weight was determined by size exclusion chromatography. The physicochemical characteristics (average diameter, viscosity, and physical stability) of the formulation were similar before and after adding glycerol and conducting the sterilization at the highest temperature (134°C) and the shorter exposure time (10 min). After autoclaving, the sterility test was performed and showed no detectable microbial growth. Multiple light scattering demonstrated that the formulations were kinetically stable, and the mean diameter was constant for 6 months, corroborating this result. The polymer was chemically stable in the sterilized formulation. Isotonic and sterile LNC aqueous suspensions were produced using glycerol and autoclaving. Briefly, the results open an opportunity to produce an isotonic and sterile LNC aqueous dispersion applicable as nanomedicine for intravenous administration in clinical trials.

Gamma sterilization of diclofenac sodium loaded- N-trimethyl chitosan nanoparticles for ophthalmic use

This study was conducted to investigate the effect of gamma irradiation on physicochemical properties of N-trimethyl chitosan (TMC), diclofenac sodium (DC) and diclofenac sodium loaded N-trimethylchitosan nanoparticles (DC-TMCNs), and to determine suitable doses of gamma rays for sterilization of DC-TMCNs. Physicochemical properties of TMC, DC and DC-TMCNs before and after exposure to gamma rays at various doses were investigated. It was found that gamma irradiation at doses of 5-25kGy did not cause any significant changes in physical and chemical properties of TMC, DC and DC-TMCNs. The bioburden of DC-TMCNs was 1.5×10⁶ CFU/vial. The initial contaminating bacteria were radiosensitive bacteria. A number of microorganisms was reduced to 10^-6 after exposure to 9.9kGy of gamma rays. Therefore, DC-TMCNs could be sterilized by gamma irradiation at a dose of 10kGy, which did not alter their physicochemical properties and did not produce any substances toxic to the eye.

Increased proapoptotic activity of electron beam irradiated doxorubicin and epirubicin in multidrug-resistant human leukemic cells

This study evaluated the effect of electron beam irradiation on the cytotoxic activity of anthracycline antibiotics such as doxorubicin (DOX), epirubicin (EPI), and dunorubicin (DAU) in human acute lymphoblastic leukemia cell line CCRF-CEM and its multidrug-resistant variant CCRF-VCR1000 cell line characterized by the overexpression of ABCB1 gene. Drugs were irradiated at doses of 10 and 25 kGy. Data from EPR studies proved that the highest concentration of free radicals was found in DOX and that the number of stable free radicals is always greater after irradiation. In in vitro studies, a higher cytotoxic activity of irradiated DOX and EPI in multidrug-resistant CCRF-VCR1000 cells was observed. This tendency was maintained during the storage at 4 °C for 90 days. Changes in CCRF-CEM cells' viability were not dependent on the irradiation status and its dose and were only drug-concentration dependent in all measurement time points. It was proved that increased potency of 25 kGy e-beam irradiated drugs results from their enhanced proapoptotic activity. Apoptotic cell death observed in CCRF-VCR1000 cells treated with irradiated drugs was caspase-8, -9, and -3 dependent and related to the increased Bax/Bcl-2 ratio. No significant differences in the effects of irradiated and non-irradiated drugs on p53 and NFκB transcription factor level and their translocation to the nucleus were noted. Increased activity of the irradiated drugs was not dependent on ABCB1 level.

Out-of-Plane Plasmonic Antennas for Raman Analysis in Living Cells

Out-of-plane plasmonic nanoantennas protruding from the substrate are exploited to perform very sensitive surface enhanced Raman scattering analysis of living cells. Cells cultured on three-dimensional surfaces exhibit tight adhesion with nanoantenna tips where the plasmonic hot-spot resides. This fact provides observable cell adhesion sites combined with high plasmonic enhancement, resulting in an ideal system for Raman investigation of cell membranes.

Cyclodextrin nanoassemblies: a promising tool for drug delivery

Among the biodegradable and nontoxic compounds that can form nanoparticles for drug delivery, amphiphilic cyclodextrins are very promising. Apart from ionic cyclodextrins, which have been extensively studied and reviewed because of their application in gene delivery, our purpose is to provide a clear description of the supramolecular assemblies of nonionic amphiphilic cyclodextrins, which can form nanoassemblies for controlled drug release. Moreover, we focus on the relationship between their structure and physicochemical characteristics, which is crucial for self assembly and drug delivery. We also highlight the importance of the nanoparticle technology preparation for the stability and application of this nanodevice.

Controlled release of raloxifene by nanoencapsulation: effect on in vitro antiproliferative activity of human breast cancer cells

Raloxifene hydrochloride (RH) is considered to be an antiproliferative agent of mammary tissue. The aim of this study was to investigate the effect of the encapsulation of RH in polymeric nanocapsules with anionic or cationic surface on its release profile and antiproliferative activity. They were prepared by interfacial deposition of preformed polymer, followed by wide physicochemical characterization. The in vitro RH release was assessed by the dialysis membrane method and the data analyzed by mathematical modeling. The antiproliferative effect on MCF-7 cell viability was investigated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay as well as by counting viable cells. They had high encapsulation efficiency, low polydispersity, and nanometric mean size. Nanocapsules prepared with Eudragit^® RS100 and Eudragit^® S100 presented positive and negative zeta potentials, respectively. Drug release studies demonstrated controlled release of RH from anionic nanocapsules, which could be explained due to a stronger interaction of the drug to these nanocapsules and the larger amount of entrapped drug. On the other hand, this control was not observed from cationic nanocapsules due to the larger amount of drug adsorbed onto their surface. MCF-7 cell viability studies and cell counting showed that RH-loaded Eudragit^® RS100 nanocapsules promote the best antiproliferative activity after 24 hours of treatment, whereas the best activity was observed for RH-loaded Eudragit^® S100 nanocapsules after 72 hours. Furthermore, the combined treatment of these formulations improved the antiproliferative effect during the entire treatment.

Challenges facing sterilization and depyrogenation of nanoparticles: effects on structural stability and biomedical applications

This review outlines and compares techniques that are currently available for the sterilization of nanoparticles and addresses the topic of endotoxin contamination. Several techniques are available for the removal of microbial contamination from nanoparticles developed for use in nanomedicine applications. These techniques include filtration, autoclaving and irradiation, as well as formaldehyde, ethylene oxide and gas plasma treatments. Of these sterilization methodologies, filtration may potentially remove microbial contamination without altering the physicochemical properties of the carrier nanoparticles, nor affecting their toxicity and functionality. However, no single process may be applied to all nanoparticle preparations and, therefore, it is recommended that each nanoparticle-drug system be validated on a case-by-case basis. From the clinical editor: This comprehensive review covers the currently available methods for removal of microbial contaminations from nanoparticles for nanomedicine applications. The review highlights the pros and cons of each available method. Authors conclude that there is no single best method and recommend a customized approach for each nanoparticle system.

Potential implications of nanoparticle characterization on in vitro and in vivo gene delivery

Nanoparticles are rapidly emerging as therapeutic delivery vectors defined by size-dependent properties. They offer several advantages over the traditional drug-delivery systems and medical diagnostics but also pose considerable challenges for systemic applications. Gene delivery is one of the important applications of nanotechnology. Usually, the nanoparticles employed for gene delivery are either formed by condensation of DNA with preformed cationic polymers or by polymerization of monomeric units thereby entrapping DNA in it. The physicochemical properties such as size, shape, surface morphology have been found to have significant influence on the gene-delivery efficacy of nanoparticles. Furthermore, when administered in vitro and in vivo, the efficiency of nanoparticles depends on a wide variety of other parameters, that is, transfection conditions, time of exposure, cell type and so forth. In this review, the potential role of characterization of nanoparticles physicochemical properties on the in vitro and in vivo gene delivery efficacy of nanoparticles is discussed.

Scale up, optimization and stability analysis of Curcumin C3 complex-loaded nanoparticles for cancer therapy

Background

Nanoparticle based delivery of anticancer drugs have been widely investigated. However, a very important process for Research & Development in any pharmaceutical industry is scaling nanoparticle formulation techniques so as to produce large batches for preclinical and clinical trials. This process is not only critical but also difficult as it involves various formulation parameters to be modulated all in the same process.

Methods

In our present study, we formulated curcumin loaded poly (lactic acid-co-glycolic acid) nanoparticles (PLGA-CURC). This improved the bioavailability of curcumin, a potent natural anticancer drug, making it suitable for cancer therapy. Post formulation, we optimized our process by Reponse Surface Methodology (RSM) using Central Composite Design (CCD) and scaled up the formulation process in four stages with final scale-up process yielding 5 g of curcumin loaded nanoparticles within the laboratory setup. The nanoparticles formed after scale-up process were characterized for particle size, drug loading and encapsulation efficiency, surface morphology, in vitro release kinetics and pharmacokinetics. Stability analysis and gamma sterilization were also carried out.

Results

Results revealed that that process scale-up is being mastered for elaboration to 5 g level. The mean nanoparticle size of the scaled up batch was found to be 158.5 ± 9.8 nm and the drug loading was determined to be 10.32 ± 1.4%. The in vitro release study illustrated a slow sustained release corresponding to 75% drug over a period of 10 days. The pharmacokinetic profile of PLGA-CURC in rats following i.v. administration showed two compartmental model with the area under the curve (AUC_0-∞) being 6.139 mg/L h. Gamma sterilization showed no significant change in the particle size or drug loading of the nanoparticles. Stability analysis revealed long term physiochemical stability of the PLGA-CURC formulation.

Conclusions

A successful effort towards formulating, optimizing and scaling up PLGA-CURC by using Solid-Oil/Water emulsion technique was demonstrated. The process used CCD-RSM for optimization and further scaled up to produce 5 g of PLGA-CURC with almost similar physicochemical characteristics as that of the primary formulated batch.

Impact of Sterilization Methods on the Stability of Silk Fibroin Solution

Different sterilization techniques such as Co(60) gamma irradiation and autoclaving were used to treat the regenerated Bombyx mori silk fibroin (RSF) in aqueous solutions. The effect of the two above mentioned sterilization methods on the conformational changes and gelation rate of RSF was studied. According to the analysis of circular dichroism spectroscopy, gamma irradiation may initiate the conformational transition from random coil to β-sheet for RSF, while autoclaving shows less significant influence on the structure changes of RSF in aqueous solutions. The results also indicate that gelation time decreased to 5 days after γ-irradiation treatment while gelation time increased to 31 days after autoclave treatment. Moreover, particles of RSF in solutions changed larger and gelation time increased when autoclaving treatment time extended. However, no detectable changes of RSF secondary structure were found investigated by XRD and FTIR. Which indicated that under both sterilization methods, the RSF structure was transformed from random coil to β-sheet structure after gelation.

Sterilization of Silver Nanoparticles Using Standard Gamma Irradiation Procedure Affects Particle Integrity and Biocompatibility

Silver nanoparticles are commonly used in a variety of commercial and medical products. Here we investigate the effects of standard sterilization methods, including heat/steam (autoclave) and gamma-irradiation on the structural integrity and biocompatibility of citrate-stabilized silver nanoparticles with nominal sizes of 20, 40, 60 and 80 nm. Particle size, shape and in vitro biocompatibility were studied pre- and post-sterilization. Sterilization by gamma irradiation at dose levels commonly used in medical device industry (15, 25 and 50 kGy) resulted in dramatic changes in particle size and morphology, as monitored by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Exposing the particles to a chemical producer of hydroxyl radicals (N-hydroxy-2-pyridinethione) allowed us to duplicate the sterilization-based changes in size and morphology, implying a free radical mechanism of action. Compared to untreated controls, we also observed a three- to five-fold increase in tendency of sterilized silver nanoparticles to cause platelet aggregation, a sensitive in vitro indicator of thrombogenicity.

Nano-microparticles as immune adjuvants: correlating particle sizes and the resultant immune responses

The development of novel immune adjuvants is emerging as a significant area of vaccine delivery based on the continued necessity to amplify immune responses to a wide array of new antigens that are poorly immunogenic. This article specifically focuses on the application of nanoparticles and microparticles as vaccine adjuvants. Many investigators are in agreement that the size of the particles is crucial to their adjuvant activities. However, reports on correlating the size of particle-based adjuvants and the resultant immune responses have been conflicting, with investigators on both sides of the fence with impressive data in support of the effectiveness of particles with small sizes (submicron) over those with larger sizes (micron) and vice versa, while other investigators reported data that showed submicron- and micron-sized particles are effective to the same degree as immune adjuvants. We have generated a list of biological, immunological and, more importantly, vaccine formulation parameters that may have contributed to the inconsistency from different studies and made recommendations on future studies attempting to correlate the size of particulate adjuvants and the immune responses induced. The information gathered could lead to strategies to optimize the performance of nano-microparticles as immune adjuvants.

Methods for the preparation and manufacture of polymeric nanoparticles

This review summarizes the different methods of preparation of polymer nanoparticles including nanospheres and nanocapsules. The first part summarizes the basic principle of each method of nanoparticle preparation. It presents the most recent innovations and progresses obtained over the last decade and which were not included in previous reviews on the subject. Strategies for the obtaining of nanoparticles with controlled in vivo fate are described in the second part of the review. A paragraph summarizing scaling up of nanoparticle production and presenting corresponding pilot set-up is considered in the third part of the review. Treatments of nanoparticles, applied after the synthesis, are described in the next part including purification, sterilization, lyophilization and concentration. Finally, methods to obtain labelled nanoparticles for in vitro and in vivo investigations are described in the last part of this review.

Oral administration of peptides and proteins: nanoparticles and cyclodextrins as biocompatible delivery systems

This review discusses drawbacks to peptide and protein oral formulations related to these drugs’ chemical and physical instability. Means used to overcome such limitations are mentioned and discussed in parallel with manufacturing considerations, metabolism, absorption mechanisms and the efflux systems that peptides and proteins experience as they travel through the gastrointestinal tract. Special focus is given to the use of delivery systems based on nanoparticles and cyclodextrins. Advantages of these systems relate to the protection from degradation, enhancement of absorption, targeting and controlling the release of the drug. Biodistribution and safety issues are discussed once material from the delivery system is expected to be absorbed by the body and thus interact with biological components. Operating parameters regarding nanoparticle manufacture and composition are also overviewed since nanoparticle physicochemical characteristics influence the ability to successfully entrap the intended drug as well as interaction with body.