Protein and peptide parenteral controlled delivery

Targeted Radium Alpha Therapy in the Era of Nanomedicine: In Vivo Results

Targeted alpha-particle therapy using radionuclides with alpha emission is a rapidly developing area in modern cancer treatment. To selectively deliver alpha-emitting isotopes to tumors, targeting vectors, including monoclonal antibodies, peptides, small molecule inhibitors, or other biomolecules, are attached to them, which ensures specific binding to tumor-related antigens and cell surface receptors. Although earlier studies have already demonstrated the anti-tumor potential of alpha-emitting radium (Ra) isotopes-Radium-223 and Radium-224 (223/224Ra)-in the treatment of skeletal metastases, their inability to complex with target-specific moieties hindered application beyond bone targeting. To exploit the therapeutic gains of Ra across a wider spectrum of cancers, nanoparticles have recently been embraced as carriers to ensure the linkage of 223/224Ra to target-affine vectors. Exemplified by prior findings, Ra was successfully bound to several nano/microparticles, including lanthanum phosphate, nanozeolites, barium sulfate, hydroxyapatite, calcium carbonate, gypsum, celestine, or liposomes. Despite the lengthened tumor retention and the related improvement in the radiotherapeutic effect of 223/224Ra coupled to nanoparticles, the in vivo assessment of the radiolabeled nanoprobes is a prerequisite prior to clinical usage. For this purpose, experimental xenotransplant models of different cancers provide a well-suited scenario. Herein, we summarize the latest achievements with 223/224Ra-doped nanoparticles and related advances in targeted alpha radiotherapy.

Overcoming barriers confronting application of protein therapeutics in bone fracture healing

Bone fracture is a major contributor to debilitation and death among patients with bone diseases. Thus, osteogenic protein therapeutics and their delivery to bone have been extensively researched as strategies to accelerate fracture healing. To prevent morbidity and mortality of fractures, which occur frequently in the aging population, there is a critical need for development of first-line therapeutics. Bone morphogenic protein-2 (BMP-2) has been at the forefront of bone regeneration research for its potent osteoinduction, despite safety concerns and biophysiological obstacles of delivery to bone. However, continued pursuit of osteoinductive proteins as a therapeutic option is largely aided by drug delivery systems, playing an imperative role in enhancing safety and efficacy. In this work, we highlighted several types of drug delivery platforms and their biomaterials, to evaluate the suitability in overcoming challenges of therapeutic protein delivery for bone regeneration. To showcase the clinical considerations for each type of platform, we have assessed the most common route of administration strategies for bone regeneration, classifying the platforms as implantable or injectable. Additionally, we have analyzed the commonly utilized models and methodology for safety and efficacy evaluation of these osteogenic protein-loaded systems, to present clinical opinions for future directions of research in this field. It is hoped that this review will promote research and development of clinically translatable osteogenic protein therapeutics, while targeting first-line treatment status for achieving desired outcomes of fracture healing. Graphical abstract.

Engineering a protease-based and site-specific PEGylation-based strategy for the controlled release of exenatide

Using the commercially available antidiabetic drug exenatide (exendin-4) as a model peptide, we designed a novel exenatide derivative, termed LEX-1, comprising a 12-mer albumin-binding peptide, a protease-sensitive linker and a native exenatide. In addition, site-specific PEGylation was performed using LEX-1 as a lead sequence to generate four exenatide derivatives (LEX-2 to LEX-5). Moreover, we determined the optimal molecular weight of maleimide-derivatized PEG for the site-specific PEGylation of LEX-1 by an in vitro stability assay and an in vivo hypoglycemic efficacy test. As a result, LEX-3 (PEG10 kDa) exerted enhanced proteolytic stability, rational release rate of free exenatide and the best glucose-stabilizing capability compared with others. In addition, the prolonged hypoglycemic effects of LEX-1 and LEX-3 were demonstrated in type 2 diabetic mice by multiple OGTTs and a hypoglycemic duration test. Furthermore, a pharmacokinetic test was conducted using Sprague Dawley (SD) rats; LEX-3 (PEG10 kDa) showed the best circulating t 1/2 of ∼119.7 h for exenatide release from LEX-3, suggesting that LEX-3 has the potential to be developed into a once-weekly antidiabetic agent. The consecutive 8 week treatment of both LEX-1 and LEX-3 exhibited enhanced beneficial efficacies on body weight gain, cumulative food intake, % fat and hemoglobin A1c (HbA1c) reduction compared with exenatide treatment. Meanwhile, the chronic administration of LEX-1 and LEX-3 also effectively improved the blood biochemical indexes. Our results indicate the enhanced antidiabetic effects of LEX-1 and LEX-3, and our strategy of PEGylation and albumin conjugation can be applied to other bioactive agents.

Hydrogels For Peptide Hormones Delivery: Therapeutic And Tissue Engineering Applications

Peptides are the most abundant biological compounds in the cells that act as enzymes, hormones, structural element, and antibodies. Mostly, peptides have problems to move across the cells because of their size and poor cellular penetration. Therefore, a carrier that could transfer peptides into cells is ideal and would be effective for disease treatment. Until now, plenty of polymers, e.g., polysaccharides, polypeptides, and lipids were used in drug delivery. Hydrogels made from polysaccharides showed significant development in targeted delivery of peptide hormones because of their natural characteristics such as networks, pore sizes, sustainability, and response to external stimuli. The main aim of the present review was therefore, to gather the important usages of the hydrogels as a carrier in peptide hormone delivery and their application in tissue engineering and regenerative medicine.

A Versatile Biocompatible Antibiotic Delivery System Based on Self-Assembling Peptides with Antimicrobial and Regenerative Potential

Periodontitis is a chronic inflammatory and tissue-destructive disease. Since the polymicrobiome in the oral cavity makes it difficult to treat, novel therapeutic strategies are required. Hydrogels based on self-assembling peptides (SAP) can be suitable candidates for periodontal therapy due to their injectability, biocompatibility, cargo-loading capacity, and tunable physicochemical and mechanical properties. In this study, two SAP hydrogels (P11-4 and P11-28/29) are examined for their intrinsic antimicrobial activity, regenerative potential, and antibiotic delivery capacity. A significant antibacterial effect of P11-28/29 hydrogels on the periodontal pathogen Porphyromonas gingivalis and a less pronounced effect for P11-4 hydrogels is demonstrated. The metabolic activity rates of human dental follicle stem cells (DFSCs), which reflect cell viability and may thus indicate the regenerative capacity, are similar on tissue culture polystyrene (TCPS) and on P11-4 hydrogels after 14 days of culture. Noticeably, both SAP hydrogels strengthen the osteogenic differentiation of DFSCs compared with TCPS. The incorporation of tetracycline, ciprofloxacin, and doxycycline does not affect fibril formation of either SAP hydrogel and results in favorable release kinetics up to 120 h. In summary, this study reveals that P11-SAP hydrogels combine many favorable properties required to make them applicable as prospective novel treatment strategy for periodontal therapy.

A novel selective VPAC2 agonist peptide-conjugated chitosan modified selenium nanoparticles with enhanced anti-type 2 diabetes synergy effects

A novel neuroendocrine peptide, pituitary adenylate cyclase activating peptide (PACAP), was found to have an important role in carbohydrate or lipid metabolism and was susceptible to dipeptidyl peptidase IV degradation. It can not only mediate glucose-dependent insulin secretion and lower blood glucose by activating VPAC2 receptor, but also raise blood glucose by promoting glucagon production by VPAC1 receptor activation. Therefore, its therapeutic application is restricted by the exceedingly short-acting half-life and the stimulatory function for glycogenolysis. Herein, we generated novel peptide-conjugated selenium nanoparticles (SeNPs; named as SCD), comprising a 32-amino acid PACAP-derived peptide DBAYL that selectively binds to VPAC2, and chitosan-modified SeNPs (SeNPs-CTS, SC) as slow-release carrier. The circulating half-life of SCD is 14.12 h in mice, which is 168.4-and 7.1-fold longer than wild PACAP (~5 min) and DBAYL (~1.98 h), respectively. SCD (10 nmol/L) significantly promotes INS-1 cell proliferation, glucose uptake, insulin secretion, insulin receptor expression and also obviously reduces intracellular reactive oxygen species levels in H₂O₂-injured INS-1 cells. Furthermore, the biological effects of SCD are stronger than Exendin-4 (a clinically approved drug through its insulinotropic effect), DBAYL, SeNPs or SC. A single injection of SCD (20 nmol/kg) into db/db mice with type 2 diabetes leads to enhanced insulin secretion and sustained hypoglycemic effect, and the effectiveness and duration of SCD in enhancing insulin secretion and reducing blood glucose levels are much stronger than Exendin-4, SeNPs or SC. In db/db mice, chronic administration of SCD by daily injection for 12 weeks markedly improved glucose and lipid profiles, insulin sensitivity and the structures of pancreatic and adipose tissue. The results indicate that SC can play a role as a carrier for the slow release of bioactive peptides and SCD could be a hopeful therapeutic against type 2 diabetes through the synergy effects of DBAYL and SeNPs.

Self-assembled peptide nanomaterials for biomedical applications: promises and pitfalls

Over the last several decades, a great number of advances have been made in the area of self-assembled supramolecules for regenerative medicine. Such advances have involved the design, preparation, and characterization of brand new self-assembled peptide nanomaterials for a variety of applications. Among all biomolecules considered for self-assembly applications, peptides have attracted a great deal of attention as building blocks for bottom-up fabrication, due to their versatility, ease of manufacturing, low costs, tunable structures, and versatile properties. Herein, some of the more exciting new designs of self-assembled peptides and their associated unique features are reviewed and several promising applications of how self-assembled peptides are advancing drug delivery, tissue engineering, antibacterial therapy, and biosensor device applications are highlighted.

A review of solute encapsulating nanoparticles used as delivery systems with emphasis on branched amphipathic peptide capsules

Various strategies are being developed to improve delivery and increase the biological half-lives of pharmacological agents. To address these issues, drug delivery technologies rely on different nano-sized molecules including: lipid vesicles, viral capsids and nano-particles. Peptides are a constituent of many of these nanomaterials and overcome some limitations associated with lipid-based or viral delivery systems, such as tune-ability, stability, specificity, inflammation, and antigenicity. This review focuses on the evolution of bio-based drug delivery nanomaterials that self-assemble forming vesicles/capsules. While lipid vesicles are preeminent among the structures; peptide-based constructs are emerging, in particular peptide bilayer delimited capsules. The novel biomaterial-Branched Amphiphilic Peptide Capsules (BAPCs) display many desirable properties. These nano-spheres are comprised of two branched peptides-bis(FLIVI)-K-KKKK and bis(FLIVIGSII)-K-KKKK, designed to mimic diacyl-phosphoglycerides in molecular architecture. They undergo supramolecular self-assembly and form solvent-filled, bilayer delineated capsules with sizes ranging from 20 nm to 2 μm depending on annealing temperatures and time. They are able to encapsulate different fluorescent dyes, therapeutic drugs, radionuclides and even small proteins. While sharing many properties with lipid vesicles, the BAPCs are much more robust. They have been analyzed for stability, size, cellular uptake and localization, intra-cellular retention and, bio-distribution both in culture and in vivo.

A novel recombinant slow-release TNF α-derived peptide effectively inhibits tumor growth and angiogensis

RMP16, a recombinant TNF α-derived polypeptide comprising a specific human serum albumin (HSA)-binding 7-mer peptide identified by phage display screening (WQRPSSW), a cleavage peptide for Factor Xa (IEGR), and a 20-amino acid bioactive peptide P16 (TNF α segment including amino acid residues 75–94), was prepared by gene-engineering technology. RMP16 showed prolonged half-life, 13.11 hours in mice (half-lives of P16 and TNF α are 5.77 and 29.0 minutes, respectively), and obviously higher receptor selectivity for TNFRI than TNF α. RMP16 had significant inhibition effects for multiple tumor cells, especially prostate cancer Du145 cells, and human vascular endothelial cells but not for human mammary non-tumorigenic epithelial cells. RMP16 can more effectively induce apoptosis and inhibit proliferation for DU145 cells than P16 and TNF α via the caspase-dependent apoptosis pathway and G0/G1 cell cycle arrest. In nude mice with transplanted tumor of DU145 cells, RMP16 significantly induced apoptosis and necrosis of tumor tissues but causing less side effects, and tumor inhibitory rate reached nearly 80%, furthermore, RMP16 can potently inhibit tumor angiogenesis and neovascularization. These findings suggest that RMP16 may represent a promising long-lasting antitumor therapeutic peptide with less TNF α-induced toxicity.

Current status of nanomedicine and nanosurgery

Nanotechnology is a multidisciplinary field that covers a vast and diverse array of devices derived from physics, biology, engineering, and chemistry. Applications of nanotechnology to medicine and physiology imply materials and devices designed to interact with the body at subcellular (i.e., molecular) scales with a high degree of specificity. There is considerable useful information about nanotechnology available and already in use. However, at present, it is very incomplete and scattered. We realized many doctors are unaware of nanotechnology used during surgery and its future prospects in patients. Though most medical products that use nanotechnology are still in the research and development stage, there are a few which are commercially available. Nanotechnology has grown by leaps and bounds over the last few years; applications of this technology in the field of medicine and surgery have been an important spin-off. Many biological structures are at nanometer scale used by surgeons in orthopedic, dental, and neurosurgeries. This article starts with the basics of the nanotechnology and how it is utilized through most medical products. This important article, which is felt to offer high educational value for the doctors, have been selected from an extensive search on the internet, and elaborately discussed. In this review, the scientific and technical aspects of nanotechnology are introduced, and some of its potential clinical applications are discussed.

Click-crosslinked injectable hyaluronic acid hydrogel is safe and biocompatible in the intrathecal space for ultimate use in regenerative strategies of the injured spinal cord

Traumatic spinal cord injury (SCI) causes damage and degeneration at and around the lesion site resulting in a loss of function. SCI presents a complex regenerative problem due to the multiple aspects of growth inhibition and the heterogeneity in size, shape and extent of injury. Currently, there is no widely accepted treatment strategy available and delivering biomolecules to the central nervous system remains a challenge. With a view towards achieving local release, we designed a hydrogel that can be injected into the intrathecal space. Here we describe the synthesis and characterization of a click-crosslinked hyaluronic acid hydrogel and demonstrate controlled in vitro release of bioactive brain derived neurotrophic factor. Importantly, we demonstrate that this new hydrogel is both biocompatible in the intrathecal space based on immunohistochemistry of the host tissue response and safe based on behavioral analysis of locomotor function.

A recombinant slow-release PACAP-derived peptide alleviates diabetes by promoting both insulin secretion and actions

Pituitary adenylate cyclase activating polypeptide (PACAP) is a neuroendocrine factor that activates both the receptor VPAC1 and VPAC2. Although PACAP possesses insulinotropic activity, its therapeutic application is limited by the extremely short acting half-life and the stimulatory effects on glucagon production via a VPAC1-dependent mechanism. Here we have generated a recombinant PACAP-derived peptide (named as MHDBAY) comprising a 7-mer albumin-binding peptide identified by phage display screening (WQRPSSW), a cleavage peptide for Factor Xa (FXa) and dipeptidyl peptidase IV (DPP IV), and a 31-amino acid PACAP-derived peptide (DBAY) that can specifically bind to the VPAC2 receptor. MHDBAY binds to albumin both in vitro and in animals, thereby leading to an orderly slow release of the active peptide DBAY via the protease cleavage. In db/db mice and New Zealand rabbits, the circulating half-life of MHDBAY is approximately 12.2 h, which is 146-fold longer than DBAY (∼5 min). A single injection of MHDBAY into db/db diabetic mice markedly increases insulin secretion, thereby leading to sustained alleviation of hyperglycemia. The potency and duration of MHDBAY in increasing insulin secretion and decreasing blood glucose levels is much greater than Exendin-4, an anti-diabetic drug via its insulinotropic actions. Furthermore, chronic administration of MHDBAY by daily injection for 8 weeks significantly improves both glucose and lipid profiles and also greatly increases insulin sensitivity in db/db mice. These findings suggest that serum albumin may act as a reservoir for slow-release of small bioactive peptides, and MHDBAY may represent a promising therapeutic peptide for diabetes.

Recent developments in protein and peptide parenteral delivery approaches

Discovery of insulin in the early 1900s initiated the research and development to improve the means of therapeutic protein delivery in patients. In the past decade, great emphasis has been placed on bringing protein and peptide therapeutics to market. Despite tremendous efforts, parenteral delivery still remains the major mode of administration for protein and peptide therapeutics. Other routes such as oral, nasal, pulmonary and buccal are considered more opportunistic rather than routine application. Improving biological half-life, stability and therapeutic efficacy is central to protein and peptide delivery. Several approaches have been tried in the past to improve protein and peptide in vitro/in vivo stability and performance. Approaches may be broadly categorized as chemical modification and colloidal delivery systems. In this review we have discussed various chemical approaches such as PEGylation, hyperglycosylation, mannosylation, and colloidal carriers including microparticles, nanoparticles, liposomes, carbon nanotubes and micelles for improving protein and peptide delivery. Recent developments on in situ thermosensitive gel-based protein and peptide delivery have also been described. This review summarizes recent developments on some currently existing approaches to improve stability, bioavailability and bioactivity of peptide and protein therapeutics following parenteral administration.

Injectable implants for the sustained release of protein and peptide drugs

Protein and peptide macromolecules have emerged as promising therapeutic agents in recent years. However, their delivery to the target site can be challenging owing to their susceptibility to denaturation and degradation, short half-life and, therefore, poor bioavailability. In situ-forming implants present an attractive parenteral delivery platform for proteins and peptides because of their ease of application, sustained-release properties, tissue biocompatibility and simple manufacture. In this review, we discuss the various mechanisms by which polymer systems assemble in situ to form implant devices for sustained release of therapeutic macromolecules, and highlight recent advances in polymer systems that gel in response to a combination of these mechanisms. Finally, we examine release mechanisms, marketed products and limitations of injectable implants.

Self-assembling, protein-based intracellular bacterial organelles: emerging vehicles for encapsulating, targeting and delivering therapeutical cargoes

Many bacterial species contain intracellular nano- and micro-compartments consisting of self-assembling proteins that form protein-only shells. These structures are built up by combinations of a reduced number of repeated elements, from 60 repeated copies of one unique structural element self-assembled in encapsulins of 24 nm to 10,000-20,000 copies of a few protein species assembled in a organelle of around 100-150 nm in cross-section. However, this apparent simplicity does not correspond to the structural and functional sophistication of some of these organelles. They package, by not yet definitely solved mechanisms, one or more enzymes involved in specific metabolic pathways, confining such reactions and sequestering or increasing the inner concentration of unstable, toxics or volatile intermediate metabolites. From a biotechnological point of view, we can use the self assembling properties of these particles for directing shell assembling and enzyme packaging, mimicking nature to design new applications in biotechnology. Upon appropriate engineering of the building blocks, they could act as a new family of self-assembled, protein-based vehicles in Nanomedicine to encapsulate, target and deliver therapeutic cargoes to specific cell types and/or tissues. This would provide a new, intriguing platform of microbial origin for drug delivery.

The effect of protein structure on their controlled release from an injectable peptide hydrogel

Hydrogel materials are promising vehicles for the delivery of protein therapeutics. Proteins can impart physical interactions, both steric and electrostatic in nature, that influence their release from a given gel network. Here, model proteins of varying hydrodynamic diameter and charge are directly encapsulated and their release studied from electropositive fibrillar hydrogels prepared from the self-assembling peptide, MAX8. Hydrogelation of MAX8 can be triggered in the presence of proteins for their direct encapsulation with neither effect on protein structure nor the hydrogel's mechanical properties. Bulk release of the encapsulated proteins from the hydrogels was assessed for a month time period at 37 °C before and after syringe delivery of the loaded gels to determine the influence of the protein structure on release. Release of positively charged and neutral proteins was largely governed by the sterics imposed by the network. Conversely, negatively charged proteins interacted strongly with the positively charged fibrillar network, greatly restricting their release to <10% of the initial protein load. Partition and retention studies indicated that electrostatic interactions dictate the amount of protein available for release. Importantly, when protein encapsulated gels were delivered via syringe, the release profiles of the macromolecules show the similar trends as those observed for non-sheared gels. This study demonstrates that proteins can be directly encapsulated in self assembled MAX8 hydrogels, which can then be syringe delivered to a site where subsequent release is controlled by protein structure.

Self-assembling materials for therapeutic delivery

A growing number of medications must be administered through parenteral delivery, i.e., intravenous, intramuscular, or subcutaneous injection, to ensure effectiveness of the therapeutic. For some therapeutics, the use of delivery vehicles in conjunction with this delivery mechanism can improve drug efficacy and patient compliance. Macromolecular self-assembly has been exploited recently to engineer materials for the encapsulation and controlled delivery of therapeutics. Self-assembled materials offer the advantages of conventional crosslinked materials normally used for release, but also provide the ability to tailor specific bulk material properties, such as release profiles, at the molecular level via monomer design. As a result, the design of materials from the "bottom up" approach has generated a variety of supramolecular devices for biomedical applications. This review provides an overview of self-assembling molecules, their resultant structures, and their use in therapeutic delivery. It highlights the current progress in the design of polymer- and peptide-based self-assembled materials.

Macromolecular diffusion and release from self-assembled beta-hairpin peptide hydrogels

Self-assembling peptide hydrogels are used to directly encapsulate and controllably release model FITC-dextran macromolecules of varying size and hydrodynamic diameters. MAX1 and MAX8 are two peptide sequences with different charge states that have been designed to intramolecularly fold and self assemble into hydrogels at physiological buffer conditions (pH 7.4, 150 mM NaCl). When self-assembly is initiated in the presence of dextran or protein probes, these macromolecules are directly encapsulated in the gel. Self-diffusion studies using fluorescence recovery after photobleaching (FRAP) and bulk release studies indicate that macromolecule mobility within, and release out of, these gels can be modulated by varying the hydrogel mesh size. The average mesh size can be modulated by simply varying the concentration of a given peptide used to construct the gel or by altering the peptide sequence. In addition, results suggest that electrostatic interactions between the macromolecules and the peptide network influence mobility and release. Depending on probe size, release half-lives can be varied from 8h to over a month.

Micro/nanostructured polymeric systems for biomedical and pharmaceutical applications

This review provides an outline of the polymeric micro/nanostructured advanced systems that are suited for the controlled and targeted administration of, specifically, nonconventional drugs. The contribution of new trends in drug-delivery technology is focused on two major parts, dealing with brief surveys of: the biodegradable/bioerodible polymeric systems used in the formulation of micro/nanoparticles and techniques used in the preparation of micro/nanoparticles for their biomedical application in cancer treatment specifically, in inflammation pathologies, as oxygen carriers (blood substitutes) and in tissue-engineering practice. A small discussion of the future perspectives of the described systems is also given.

Releasable PEGylation of proteins with customized linkers

Releasable PEGylation employs customized linkers that reversibly tether a therapeutic moiety with polyethylene glycol polymers. The choice of releasable PEG linkers may have numerous applications that are insufficiently addressed by stable polymer attachment. Releasable PEGylation provides regeneration of authentic and fully active drug and allows tailored design of critical pharmacological parameters such as the maximal drug concentration and total drug exposure. This provides a prodrug format that combines beneficial attributes of PEGylation with controlled release. The linker release mechanisms are shown to be kinetically controlled by the design of a hydrolytically labile center and side chains for the steric modulation of the intramolecular elimination reactions and linker self-immolation. Recent reports have described both aromatic and aliphatic based customized linkers that release the unaltered original drug under physiological conditions and at therapeutically useful release rates. These studies have examined bioconjugates of cytokines, peptide hormones, immunotoxins, enzymes, and reporter proteins.

On the design of in situ forming biodegradable parenteral depot systems based on insulin loaded dialkylaminoalkyl-amine-poly(vinyl alcohol)-g-poly(lactide-co-glycolide) nanoparticles

The feasibility to generate in situ forming parenteral depot systems from insulin loaded dialkylaminoalkyl-amine-poly(vinyl alcohol)-g-poly(lactide-co-glycolide) nanoparticles, was investigated. Biodegradable nanoparticles formed polymeric semi-solid depots upon injection into isotonic phosphate buffered saline (PBS) with no additional initiators. Nanoparticles (NP) prepared from the different amine-modified polyesters displayed a pronounced positive zeta-potential of >25 mV. Diethylaminopropyl-amine-poly(vinyl alcohol)-g-poly(lactide-co-glycolide) (DEAPA(68)-PVAL-g-PLGA(1:20)), diethylaminoethyl-amine-poly(vinyl alcohol)-g-poly(lactide-co-glycolide) (DEAEA(33)-PVAL-g-PLGA(1:20)), and dimethylaminopropyl-amine-poly(vinyl alcohol)-g-poly(lactide-co-glycolide) (DMAPA(33)-PVAL-g-PLGA(1:20)), formed in situ depots by an ion-mediated aggregation with subsequent fusion of nanoparticles, related to a decreased glass transition temperature in the presence of PBS. Moreover, two factors, namely, polymer and insulin-nanocomplex concentration, were evaluated using a response surface design with respect to nanoparticles formation and insulin loading. Nanoparticles and implants were investigated by atomic force microscopy (AFM). The in vitro release from implants loaded with 2% insulin was carried out in a flow trough cell and quantified by high performance liquid chromatography (HPLC). The release showed a triphasic profile with an initial burst, pore diffusion and diffusion from the swollen matrix over more than two weeks. Insulin distribution in the implants during the release was followed by confocal laser scanning microscopy (CLSM). These findings combined with the protection of the model peptide against competitive macromolecules and the possibility to get dry powders by lyophilization make these nanoparticles-based depots suitable candidates for the design of controlled release devices for bioactive macromolecules.

The present and future of nanotechnology in human health care

Nanotechnology is a multidisciplinary field that covers a vast and diverse array of devices derived from engineering, physics, chemistry, and biology. The burgeoning new field of nanotechnology, opened up by rapid advances in science and technology, creates myriad new opportunities for advancing medical science and disease treatment in human health care. Applications of nanotechnology to medicine and physiology imply materials and devices designed to interact with the body at subcellular (i.e., molecular) scales with a high degree of specificity. This can be potentially translated into targeted cellular and tissue-specific clinical applications designed to achieve maximal therapeutic efficacy with minimal side effects. In this review the chief scientific and technical aspects of nanotechnology are introduced, and some of its potential clinical applications are discussed.

Nanomedicine

The intricate problems associated with the delivery and various unnecessary in vivo transitions of proteins and drugs needs to be tackled soon to be able to exploit the myriad of putative therapeutics created by the biotechnology boom. Nanomedicine is one of the most promising applications of nanotechnology in the field of medicine. It has been defined as the monitoring, repair, construction and control of human biological systems at the molecular level using engineered nanodevices and nanostructures. These nanostructured medicines will eventually turn the world of drug delivery upside down. PEGylation (i.e. the attachment of polyethylene glycol to proteins and drugs) is an upcoming methodology for drug development and it has the potential to revolutionise medicine by drastically improving the pharmacokinetic and pharmacodynamic properties of the administered drug. This article provides a total strategy for improving the therapeutic efficacy of various biotechnological products in drug delivery. This article also presents an extensive analysis of most of the PEGylated proteins, peptides and drugs, together with extensive clinical data. Nanomedicines and PEGylation, the latest offshoots of nanotechnology will definitely pave a way in the field of drug delivery where targeted delivery, formulation, in vivo stability and retention are the major challenges.