Recent advances in small molecule drug delivery

Self-assembling peptides as immunomodulatory biomaterials

Self-assembling peptides are a type of biomaterial rapidly emerging in the fields of biomedicine and material sciences due to their promise in biocompatibility and effectiveness at controlled release. These self-assembling peptides can form diverse nanostructures in response to molecular interactions, making them versatile materials. Once assembled, the peptides can mimic biological functions and provide a combinatorial delivery of therapeutics such as cytokines and drugs. These self-assembling peptides are showing success in biomedical settings yet face unique challenges that must be addressed to be widely applied in the clinic. Herein, we describe self-assembling peptides' characteristics and current applications in immunomodulatory therapeutics.

Algal Polysaccharides-Based Hydrogels: Extraction, Synthesis, Characterization, and Applications

Hydrogels are three-dimensional crosslinked hydrophilic polymer networks with great potential in drug delivery, tissue engineering, wound dressing, agrochemicals application, food packaging, and cosmetics. However, conventional synthetic polymer hydrogels may be hazardous and have poor biocompatibility and biodegradability. Algal polysaccharides are abundant natural products with biocompatible and biodegradable properties. Polysaccharides and their derivatives also possess unique features such as physicochemical properties, hydrophilicity, mechanical strength, and tunable functionality. As such, algal polysaccharides have been widely exploited as building blocks in the fabrication of polysaccharide-based hydrogels through physical and/or chemical crosslinking. In this review, we discuss the extraction and characterization of polysaccharides derived from algae. This review focuses on recent advances in synthesis and applications of algal polysaccharides-based hydrogels. Additionally, we discuss the techno-economic analyses of chitosan and acrylic acid-based hydrogels, drawing attention to the importance of such analyses for hydrogels. Finally, the future prospects of algal polysaccharides-based hydrogels are outlined.

Local delivery of biocompatible lentinan/chitosan composite for prolonged inhibition of postoperative breast cancer recurrence

Postsurgical localized chemotherapy for breast cancer recurrence (BCR) still faces many problems which dampen researchers' enthusiasm and discounted prognosis. Simple strategies with controllable toxicities are expected to address these hurdles. Lentinan (LNT) has excellent biocompatibility and notable antitumor activity but rather low bioavailability after intravenous or oral administration. Here, a sponge-like LNT/chitosan composite (LNT/CS sponge) was prepared for efficient local delivery to prevent postoperative BCR. The obtained sponges exhibit uniform porosity and sustained release of LNT in vitro and in vivo. Furthermore, the sponges were implanted and showed significant reduction of postsurgical recurrence and suppression of long-term tumor regrowth with favorable biocompatibility in a subcutaneous postsurgical recurrence mouse model. Subsequent studies revealed that LNT can restrain the stemness of breast cancer cells, which may account for the long-term inhibition of tumor relapse. Therefore, LNT/CS sponge has a great potential as a promising alternative for postsurgical BCR.

Discovery of a novel class of small-molecule antibacterial agents against Staphylococcus aureus

Background: With constantly increasing resistance against the known antibiotics, the search for novel antibacterial compounds is a challenge. The number of synthetic antibacterial agents is limited. Materials & methods: We discovered novel small-molecule antibacterial agents that are accessible via a simple two-step procedure. The evaluation against Staphylococcus aureus showed antibacterial effects depending on the substituent positioning at the residues of the molecular scaffold. Additionally, we investigated the potential of the compounds to increase the antibacterial activity of tetracycline. Results: The most effective antibacterial compounds possessed a 3-methoxy function at an aromatic residue. In combination with tetracycline, we found a strong effect for a few compounds in boosting the antibacterial activity, so the first promising lead compounds with dual activities could be identified.

Principles of the activin receptor signaling pathway and its inhibition

This review captures the anabolic and stimulatory effects observed with inhibition of the transforming growth factor β superfamily in muscle, blood, and bone. New medicinal substances that rectify activin, myostatin, and growth differentiation factor 11 signaling give hope to the many whose lives are affected by deterioration of these tissues. The review first covers the origin, structure, and common pathway of activins, myostatin, and growth differentiation factor 11 along with the pharmacodynamics of the new class of molecules designed to oppose the activin receptor signaling pathway. Current terminology surrounding this new class of molecules is inconsistent and does not infer functionality. Adopting inhibitors of the activin receptor signaling pathway (IASPs) as a generic term is proposed because it encapsulates the molecular mechanisms along the pathway trajectory. To conclude, a pragmatic classification of IASPs is presented that integrates functionality and side effects based on the data available from animals and humans. This provides researchers and clinicians with a tool to tailor IASPs therapy according to the need of projects or patients and with respect to side effects.

Encapsulation and <i>In Vitro </i>Controlled Release of Doxycycline in Temperature-Sensitive Hydrogel Composed of Polyethyleneglycol–polypeptide (L-Alanine-co-L-Aspartate)

Doxycycline was loaded with synthesized micelles composed of methyl Poly (ethylene glycol-block-poly (L-alanine–co–L-aspartate), or mPEG–Ala–Asp, and then characterized as a drug delivery carrier. The synthesis of the temperature-sensitive mPEG–Ala–Asp block copolymer was carried out by two-step ring-opening polymerization: firstly, the mPEG reacts with L-alanine N-carboxylic anhydride, and secondly the resulting mPEG–Ala reacts with benzyl aspartate N-carboxylic anhydride. The molecular structure of the copolymers obtained was determined by FT-IR and NMR spectroscopy methods and the micelles were characterized by SEM, TEM and DLS, respectively. The controlled release of Dox from hydrogel in the presence of PBS (8 to 9% by weight) lasts 6 to 7 days exhibiting stable release rates. The drug release mechanisms were studied: Higuchi and zero order models. The results and correlation coefficients applied to the Higuchi and zero-order models. The findings show the potential use of mPEG–Ala–Asp as an effective depot matrix to deliver anthracycline class drugs.

In vitro study of SDF-1α-loaded injectable and thermally responsive hydrogels for adipose stem cell therapy by SDF-1/CXCR4 axis

Stem cell-based approaches have become a promising therapeutic strategy for treating ischemic diseases. The aim of this study was to develop injectable hydrogel systems for the local release of stromal cell-derived factor-1α (SDF-1α) to recruit adipose stem cells (ASCs) that express CXCR4 to achieve stem cell therapy and therapeutic angiogenesis. Thermoresponsive and injectable chitosan (CS)/β-glycerophosphate disodium salt pentahydrate (βGP) hydrogels with different concentrations of hyaluronic acid (HA) were designed and fabricated to achieve local and sustained release of SDF-1α for ASC recruitment. Herein, the material structures, physical properties, gelation temperature, and gelation time of hydrogels with different compositions were determined. The incorporation of 0.9% HA in CS-based hydrogels not only enhanced the gelation time but also increased the strength of the hydrogels. In addition, the results revealed that the thermoresponsive and injectable CS/βGP/HA hydrogels showed good biocompatibility. In addition, the in vitro release profiles showed that the hydrogels achieved sustained release of SDF-1α over 7 days and enhanced ASC migration. The results revealed that the hydrogels with HA enhanced the sustained release effect compared with the hydrogel without HA, indicating that the HA content regulated the physical and release properties of the injectable hydrogels. Therefore, thermoresponsive and injectable CS/βGP/HA hydrogels may provide an alternative for treating ischemic diseases via SDF-1/CXCR4 axis for ASC recruitment and retention.

Lipid-oligonucleotide conjugates for bioapplications

Lipid-oligonucleotide conjugates (LONs) are powerful molecular-engineering materials for various applications ranging from biosensors to biomedicine. Their unique amphiphilic structures enable the self-assembly and the conveyance of information with high fidelity. In particular, LONs present remarkable potential in measuring cellular mechanical forces and monitoring cell behaviors. LONs are also essential sensing tools for intracellular imaging and have been employed in developing cell-surface-anchored DNA nanostructures for biomimetic-engineering studies. When incorporating therapeutic oligonucleotides or small-molecule drugs, LONs hold promise for targeted therapy. Moreover, LONs mediate the controllable assembly and fusion of vesicles based on DNA-strand displacements, contributing to nanoreactor construction and macromolecule delivery. In this review, we will summarize the general synthesis strategies of LONs, provide some characterization analysis and emphasize recent advances in bioanalytical and biomedical applications. We will also consider the relevant challenges and suggest future directions for building better functional LONs in nanotechnology and materials-science applications.

A functional chitosan-based hydrogel as a wound dressing and drug delivery system in the treatment of wound healing

Functional active wound dressings are expected to provide a moist wound environment, offer protection from secondary infections, remove wound exudate and accelerate tissue regeneration, as well as to improve the efficiency of wound healing. Chitosan-based hydrogels are considered as ideal materials for enhancing wound healing owing to their biodegradable, biocompatible, non-toxic, antimicrobial, biologically adhesive, biological activity and hemostatic effects. Chitosan-based hydrogels have been demonstrated to promote wound healing at different wound healing stages, and also can alleviate the factors against wound healing (such as excessive inflammatory and chronic wound infection). The unique biological properties of a chitosan-based hydrogel enable it to serve as both a wound dressing and as a drug delivery system (DDS) to deliver antibacterial agents, growth factors, stem cells and so on, which could further accelerate wound healing. For various kinds of wounds, chitosan-based hydrogels are able to promote the effectiveness of wound healing by modifying or combining with other polymers, and carrying different types of active substances. In this review, we will take a close look at the application of chitosan-based hydrogels in wound dressings and DDS to enhance wound healing.

Silver-Coated Colloidosomes as Carriers for an Anticancer Drug

Small drug molecules are widely developed and used in the pharmaceutical industry. In the past few years, loading and delivering such molecules using polymer-shell colloidosomes has attracted interest. Traditional polymer capsules fail to encapsulate low-molecular-weight materials for long times, since they are inherently porous and permeable for small molecules. In this paper, we report a method for encapsulating an anticancer drug with small molecule weight, for cell viability tests. The silver-coated colloidosomes are prepared by making an aqueous core capsule with a polymer shell and then adding AgNO₃, surfactant, and l-ascorbic acid to form a second shell. The capsules are impermeable and can be triggered using ultrasound. We propose to use the capsules as drug carriers. The silver demonstrates a low cytotoxicity for up to 10 capsules per cell. After the silver shells are triggered by ultrasound, the released doxorubicin, the broken silver fragments, and the doxorubicin loading on the capsule surface all kill cells. The results demonstrate a nonpermeable silver-shell microcapsule with ultrasound sensitivity for potential medical applications.

Functional Silver-Coated Colloidosomes as Targeted Carriers for Small Molecules

Colloidosomes have attracted great interest in recent years because of their capability for storage and delivery of small molecules for medical and pharmaceutical applications. However, traditional polymer shell colloidosomes leak low molecular weight drugs due to their intrinsic shell permeability. Here, we report aqueous core colloidosomes with a silver shell, which seals the core and makes the shell impermeable. The silver-coated colloidosomes were prepared by reacting l-ascorbic acid in the microcapsule core with silver nitrate in the wash solution. The silver shell colloidosomes were then modified by using 4,4'-dithiodibutyric acid and cross-linked with rabbit Immunoglobulin G (IgG). Label-free surface plasmon resonance was used to test the specific targeting of the functional silver shell with rabbit antigen. To break the shells, ultrasound treatment was used. The results demonstrate that a new type of functional silver-coated colloidosome with immunoassay targeting, nonpermeability, and ultrasound sensitivity could be applied to many medical applications.

Retracted Article: A polyurethane–chitosan brush as an injectable hydrogel for controlled drug delivery and tissue engineering

Hydrogels and porous lyophilized hydrogels have been designed using a polyurethane brush with a chitosan backbone through grafting for controlled drug delivery.

Calvarial Defect Healing Induced by Small Molecule Smoothened Agonist

Hedgehog (Hh) signaling positively regulates both endochondral and intramembranous ossification. Use of small molecules for tissue engineering applications poses several advantages. In this study, we examined whether use of an acellular scaffold treated with the small molecule Smoothened agonist (SAG) could aid in critical-size mouse calvarial defect repair. First, we verified the pro-osteogenic effect of SAG in vitro, using primary neonatal mouse calvarial cells (NMCCs). Next, a 4 mm nonhealing defect was created in the mid-parietal bone of 10-week-old CD-1 mice. The scaffold consisted of a custom-fabricated poly(lactic-co-glycolic acid) disc with hydroxyapatite coating (measuring 4 mm diameter × 0.5 mm thickness). Treatment groups included dimethylsulfoxide control (n = 6), 0.5 mM SAG (n = 7) or 1.0 mM SAG (n = 7). Evaluation was performed at 4 and 8 weeks postoperative, by a combination of high-resolution microcomputed tomography, histology (H & E, Masson's Trichrome), histomorphometry, and immunohistochemistry (BSP, OCN, VEGF). In vivo results showed that SAG treatment induced a significant and dose-dependent increase in calvarial bone healing by all radiographic parameters. Histomorphometric analysis showed an increase in all parameters of bone formation with SAG treatment, but also an increase in blood vessel number and density. In summary, SAG is a pro-osteogenic, provasculogenic stimulus when applied locally in a bone defect environment.

Intracellularly Biodegradable Polyelectrolyte/Silica Composite Microcapsules as Carriers for Small Molecules

Microcapsules that can be efficiently loaded with small molecules and effectively released at the target area through the degradation of the capsule shells hold great potential for treating diseases. Traditional biodegradable polyelectrolyte (PE) capsules can be degraded by cells and eliminated from the body but fail to encapsulate drugs with small molecular weight. Here, we report a poly-l-arginine hydrochloride (PARG)/dextran sulfate sodium salt (DEXS)/silica (SiO2) composite capsule that can be destructed in cells and of which the in situ formed inorganic SiO2 enables loading of small model molecules, Rhodamine B (Rh-B). The composite capsules were fabricated based on the layer-by-layer (LbL) technique and the hydrolysis of tetraethoxysilane (TEOS). Capsules composed of nondegradable PEs and SiO2, polyllamine hydrochloride (PAH)/poly(sodium 4-styrenesulfonate) (PSS)/silica (the control sample), were prepared and briefly compared with the degradable composite capsules. An intracellular degradation study of both types of composite capsules revealed that PARG/DEXS/silica capsules were degraded into fragments and lead to the release of model molecules in a relatively short time (2 h), while the structure of PAH/PSS/silica capsules remained intact even after 3 days incubation with B50 cells. Such results indicated that the polymer components played a significant role in the degradability of the SiO2. Specifically, PAH/PSS scaffolds blocked the degradation of SiO2. For PARG/DEXS/silica capsules, we proposed the effects of both hydrolytic degradation of amorphous silica and enzymatic degradation of PARG/DEXS polymers as a cell degradation mechanism. All the results demonstrated a new type of functional composite microcapsule with low permeability, good biocompatibility, and biodegradability for potential medical applications.

Cryomilling for the fabrication of doxorubicin-containing silica-nanoparticle/polycaprolactone nanocomposite films

Bionanocomposites need to have a homogeneous distribution of nanomaterials in the polymeric matrix to achieve consistent mechanical and biological functions. However, a significant challenge lies in achieving the homogeneous distribution of nanomaterials, particularly through a solvent-free approach. This report introduces a technology to address this need. Specifically, cryomilling, a solvent-free, low-temperature processing method, was applied to generate a bionanocomposite film with well-dispersed nanoparticles. As a proof-of-concept, polycaprolactone (PCL) and doxorubicin-containing silica nanoparticles (Si-Dox) were processed through cryomilling and subsequently heat pressed to form the PCL/Si-Dox (cPCL/Si-Dox) film. Homogeneous distribution of Si-Dox was observed under both confocal imaging and atomic force microscopy imaging. The mechanical properties of cPCL/Si-Dox were comparable to those of the pure PCL film. Subsequent in vitro release profiles suggested that sustained release of Dox from the cPCL/Si-Dox film was achievable over 50 days. When human cervical cancer cells were seeded directly on these films, uptake of Dox was observed as early as day 1 and significant inhibition of cell growth was recorded on day 5.

Triple-responsive inorganic–organic hybrid microcapsules as a biocompatible smart platform for the delivery of small molecules

We designed novel hybrid inorganic/organic capsules with unique physicochemical features enabling multimodal triggering.

Chitosan based atorvastatin nanocrystals: effect of cationic charge on particle size, formulation stability, and in-vivo efficacy

Cationic charged chitosan as stabilizer was evaluated in preparation of nanocrystals using probe sonication method. The influence of cationic charge densities of chitosan (low CS_L, medium CS_M, high CS_H molecular weights) and Labrasol^® in solubility enhancement and modifying the release was investigated, using atorvastatin (ATR) as poorly soluble model drug. Compared to CS_M and CS_H; low cationic charge of CS_L acted as both electrostatic and steric stabilizer by significant size reduction to 394 nm with charge of 21.5 meV. Solubility of ATR-CS_L increased to 60-fold relative to pure ATR and ATR-L. Nanocrystals were characterized for physiochemical properties. Scanning electron microscopy revealed scaffold-like structures with high surface area. X-ray powder diffractometry and differential scanning calorimetry revealed crystalline to slight amorphous state changes after cationic charge size reduction. Fourier transform-infrared spectra indicated no potent drug-excipient interactions. The enhanced dissolution profile of ATR-CS_L indicates that sustained release was achieved compared with ATR-L and Lipitor^®. Anti-hyperlipidemic performance was pH dependent where ATR-CS_L exhibited 2.5-fold higher efficacy at pH 5 compared to pH 6 and Lipitor^®. Stability studies indicated marked changes in size and charge for ATR-L compared to ATR-CS_L exemplifying importance of the stabilizer. Therefore, nanocrystals developed with CS_L as a stabilizer is a promising choice to enhance dissolution, stability, and in-vivo efficacy of major Biopharmaceutical Classification System II/IV drugs.

Potential use of a megamolecular polysaccharide sacran as a hydrogel-based sustained release system

A megamolecular polysaccharide sacran was newly extracted from cyanobacterium Aphanothece sacrum. Sacran has many preferable properties for transdermal application, e.g. a safe biomaterial, a high moisturizing effect, a formation of film and hydrogel. Additionally, it was recently discovered that sacran has an anti-inflammatory effect for atopic dermatitis model mice. In this study, in order to evaluate the feasibility of sacran-hydrogel as a novel sustained release system, we prepared a sacran-hydrogel containing 4-biphenyl acetic acid (BPAA, an acidic drug), prednisolone (PD, a neutral drug) or chlorpheniramine maleate (CPM, a basic drug), and performed the in vitro release studies. The sacran-hydrogel containing BPAA, PD or CPM provided a sustained release profile in accordance with a quasi-Fickian diffusion model. Furthermore, the release rate of drugs from sacran-hydrogels can be controlled by adjusting the concentration of aluminum chloride as a cross linker. These results suggest the potential use of sacran-hydrogel as a sustained release system for drugs.

Guiding principles in the design of ligand-targeted nanomedicines

Medicines for the treatment of most human pathologies are encumbered by unwanted side effects that arise from the deposition of an effective drug into the wrong tissues. The logical remedy for these undesirable properties involves selective targeting of the therapeutic agent to pathologic cells, thereby avoiding collateral toxicity to healthy cells. Since significant advantages can also accrue by incorporating a therapeutic or imaging agent into a nanoparticle, many laboratories are now combining both benefits into a single formulation. This review will focus on the major guiding principles in the design of ligand-targeted nanoparticles, including optimization of their chemical and physical properties, selection of the ideal targeting ligand, engineering of the appropriate surface passivation and linker strategies to achieve selective delivery of the entrapped cargo to the desired diseased cell.

Pharmacodynamics of diclofenac from novel Eudragit entrapped microspheres

Effective clinical utilization of non-steroidal anti-inflammatory drugs such as diclofenac sodium (DS) is significantly limited by their ulcerogenic potential and poor bioavailability after oral administration, thus necessitating the need for a better carrier to minimize these obvious limitations. The objective of this study was to evaluate Eudragit® RS100/RL100 microspheres formulated by the solvent-evaporation technique for improved delivery of diclofenac. Three batches of (DF1, DF2 and DF3) microspheres were prepared using different ratios of Eudragit RS-100 and RL-100 polymers based on the solvent-evaporation method. The microspheres were characterized based on morphological properties, particle size analysis and encapsulation efficiency (EE%). In vitro release of DS was investigated in both 0.1 N HCl (pH 1.2) and phosphate-buffered saline (pH 7.4), while anti-inflammatory studies were evaluated in the rat model. Maximum EE% of 86.61 ± 0.11, 88.14 ± 0.16 and 85.50 ± 0.21 was obtained for DF1, DF2 and DF3, respectively. Discrete, smooth and brownish microspheres of size range 437 ± 0.01-479 ± 0.21 µm were obtained. Release of DS from the formulation depends on the polymer ratio. All the batches exhibited good anti-inflammatory activities. Microsphere formulations based on Eudragit® polymers would likely offer a reliable and alternative means of delivering DS orally.

High-relaxivity and luminescent silica nanoparticles as multimodal agents for molecular imaging

The design and synthesis of a new bimodal contrast agent for magnetic resonance imaging and optical imaging is reported. Tunable-sized silica nanoparticles were synthesized by a microemulsion-mediated pathway and used as carriers for paramagnetic and luminescent probes. The near-infrared luminescent agent was a ruthenium complex that was directly entrapped in the silica shell to provide photoluminescence enhancement and to make it highly photostable as it was protected from the surrounding environment. The paramagnetic activity came from a Gd-DTPA derivative that was grafted on the silica surface. NMRD profiles showed a strong relaxivity enhancement (increase of 432% in the r1 value at 20 MHz) when the paramagnetic complex was grafted at the nanoparticle surface, because of a reduction of its mobility. Polyethylene glycol was also grafted at the nanoparticle surface to enhance the nanoparticle residence time in the bloodstream. A thorough characterization of the material confirmed its potential as a very effective bimodal contrast agent.

Preparation and characterization of an anti-inflammatory agent based on a zinc-layered hydroxide-salicylate nanohybrid and its effect on viability of Vero-3 cells

A new organic-inorganic nanohybrid based on zinc-layered hydroxide intercalated with an anti-inflammatory agent was synthesized through direct reaction of salicylic acid at various concentrations with commercially available zinc oxide. The basal spacing of the pure phase nanohybrid was 15.73 Å, with the salicylate anions arranged in a monolayer form and an angle of 57 degrees between the zinc-layered hydroxide interlayers. Fourier transform infrared study further confirmed intercalation of salicylate into the interlayers of zinc-layered hydroxide. The loading of salicylate in the nanohybrid was estimated to be around 29.66%, and the nanohybrid exhibited the properties of a mesoporous-type material, with greatly enhanced thermal stability of the salicylate compared with its free counterpart. In vitro cytotoxicity assay revealed that free salicylic acid, pure zinc oxide, and the nanohybrid have a mild effect on viability of African green monkey kidney (Vero-3) cells.

A covalently crosslinked polysaccharide hydrogel for potential applications in drug delivery and tissue engineering

The development of non-cytotoxic hydrogels that can allow for the controlled release of molecules has important clinical and therapeutic applications. In this paper, we developed a series of in situ hydrogels by combining N,O-carboxymethyl chitosan and oxidized alginate without additional crosslinking agents. The rheological properties of these hydrogels as well as their gelling time, swelling ratio, and in vitro degradation behavior were investigated. We observed that although gelation was rapid at physiological temperature, it was even faster in the presence of higher oxidization degree of alginate. In vitro cytotoxicity study showed that the developed hydrogels were not cytotoxic after 24 h of culturing with NIH-3T3 cells. Additionally, bovine serum albumin was released from the hydrogels initially by diffusion at early stages followed by a degradation-dependent mechanism at later stages. In conclusion, the developed hydrogel might have potential application in the drug delivery system and tissue engineering.

Ufasomes Mediated Cutaneous Delivery of Dexamethasone: Formulation and Evaluation of Anti-Inflammatory Activity by Carrageenin-Induced Rat Paw Edema Model

The purpose of study is to formulate and evaluate ufasomal gel of dexamethasone. Ufasomal suspension was made by sonication method using different concentrations of Span 80, Span 20 and cholesterol along with 25 mg of drug. Ufasomal gel was formulated by hydration method using carbopol 940. Ufasomal vesicles appeared as spherical and multilamellar under Transmission Electron Microscope. Ufasomal formulation prepared with drug to oleic acid molar ratio 8:2 (UF-2) produced greater number of vesicles and greater entrapment efficiency. UF-2 was optimized for further evaluation. The transdermal permeation and skin partitioning of from optimized formulation was significantly higher (P < 0.05) as compared to plain drug and plain gel formulation which is due to presence of surfactant acting as permeation enhancer. Permeation of optimized formulation was found to be about 4.7 times higher than plain drug gel. Anti-inflammatory activity evaluated by inhibition Carrageenan induced rat paw edema model. Significant reduction of edema (P < 0.10) was observed in comparison to the commercial product. Hence oleic acid based vesicles can be used as alternate carrier for topical delivery.

Chitosan-chondroitin sulphate nanoparticles for controlled delivery of platelet lysates in bone regenerative medicine

In this study, a new formulation of nanoparticles (NPs) based on the electrostatic interaction between chitosan and chondroitin sulphate (CH-CS NPs) is proposed for the controlled release of proteins and growth factors (GFs), specifically platelet lysates (PLs). These nanoparticulate carriers are particularly promising for protein entrapment because the interactions between the polysaccharides and the entrapped proteins mimic the interactions between chondroitin sulphate and proteins in the native extracellular matrix (ECM). Spherical non-cytotoxic NPs were successfully produced, exhibiting high encapsulation efficiency for physiological levels of GFs and a controlled protein release profile for > 1 month. Moreover, it was also observed that these NPs can be uptaken by human adipose-derived stem cells (hASCs), depending on the concentration of NPs in the culture medium and incubation time. This shows the versatility of the developed NPs, which, besides acting as a protein delivery system, can also be used in the future as intracellular carriers for bioactive agents, such as nucleotides. When the PL-loaded NPs were used as a replacement of bovine serum for in vitro hASCs culture, the viability and proliferation of hASCs was not compromised. The release of PLs from CH-CS NPs also proved to be effective for the enhancement of in vitro osteogenic differentiation of hASCs, as shown by the increased levels of mineralization, suggesting not only the effective role of the delivery system but also the role of PLs as an osteogenic supplement for bone tissue engineering and regenerative medicine applications.

Electrostatic surface modifications to improve gene delivery

IMPORTANCE OF THE FIELD

Gene therapy has the potential to treat a wide variety of diseases, including genetic diseases and cancer.

AREAS COVERED IN THIS REVIEW

This review introduces biomaterials used for gene delivery and then focuses on the use of electrostatic surface modifications to improve gene delivery materials. These modifications have been used to stabilize therapeutics in vivo, add cell-specific targeting ligands, and promote controlled release. Coatings of nanoparticles and microparticles as well as non-particulate surface coatings are covered in this review. Electrostatic principles are crucial for the development of multilayer delivery structures fabricated by the layer-by-layer method.

WHAT THE READER WILL GAIN

The reader will gain knowledge about the composition of biomaterials used for surface modifications and how these coatings and multilayers can be utilized to improve spatial control and efficiency of delivery. Examples are shown for the delivery of nucleic acids, including DNA and siRNA, to in vitro and in vivo systems.

TAKE HOME MESSAGE

The versatile and powerful approach of electrostatic coatings and multilayers will lead to the development of enhanced gene therapies.

Chitosan-based hydrogels for controlled, localized drug delivery

Hydrogels are high-water content materials prepared from cross-linked polymers that are able to provide sustained, local delivery of a variety of therapeutic agents. Use of the natural polymer, chitosan, as the scaffold material in hydrogels has been highly pursued thanks to the polymer's biocompatibility, low toxicity, and biodegradability. The advanced development of chitosan hydrogels has led to new drug delivery systems that release their payloads under varying environmental stimuli. In addition, thermosensitive hydrogel variants have been developed to form a chitosan hydrogel in situ, precluding the need for surgical implantation. The development of these intelligent drug delivery devices requires a foundation in the chemical and physical characteristics of chitosan-based hydrogels, as well as the therapeutics to be delivered. In this review, we investigate the newest developments in chitosan hydrogel preparation and define the design parameters in the development of physically and chemically cross-linked hydrogels.

Pharmaceutical technology management--profitable business avenue

Growing research expenditure, regulatory framework and generic erosion have forced pharmaceutical companies globally to resort to pharmaceutical technology management (PTM). Indeed, the pharmaceutical industry has witnessed the impact of innovative drug delivery and device technologies and their influence on business. PTM has given a new business insight with greater profits and enhancement of product franchise. Promising breakthrough technologies have not been able to reach a commercial platform largely owing to lack of capital at the preliminary stages of the product development program. Intellectual property plays a considerable role in protecting innovative technologies. Joint ventures and strategic alliances also become important for commercializing a new technology. The synergy of PTM with options of in-licensing is expected to infuse newer opportunities to the pharmaceutical business.

Rapidly Reversible Hydrophobization: An Approach to High First-Pass Drug Extraction

We have investigated a rapidly reversible hydrophobization of therapeutic agents for improving first-pass uptake in locoregional drug therapy. This approach involves the attachment of a hydrophobic moiety to the drug by highly labile chemical linkages that rapidly hydrolyze upon injection. Hydrophobization drastically enhances cell-membrane association of the prodrug and, consequently, drug uptake, while the rapid lability protects nontargeted tissues from exposure to the highly active agent. Using the membrane-impermeable DNA intercalator propidium iodide, and melphalan, we report results from in vitro cellular internalization and toxicity studies. Additionally, we report in vivo results after a single liver arterial bolus injection, demonstrating both tumor targeting and increased survival in a mouse tumor model.

Intercalation of hydrophilic and hydrophobic antibiotics in layered double hydroxides

Four pharmaceutically active molecules, each representing a different class of antibiotic, were intercalated in layered double hydroxides. Two of them, gramicidin and amphotericin B, are hydrophobic, surface active drugs that were incorporated in artificial membranes formed in the interlayer of the inorganic host. The other two, ampicillin and nalidixic acid, are water soluble, commonly used antibiotics that were directly intercalated by using simple ion exchange reactions. The synthetic nanohybrid materials were characterized by various methods, as X-ray diffraction, infrared spectroscopy and ultraviolet-visible spectroscopy that verified the successful intercalation of the antibiotics and provided information regarding the interlayer structure of the nanohybrids. The reversible interaction of the antibiotic molecules with the inorganic host leads to release of the active drugs under the appropriate conditions. The release studies showed that the synthetic nanohybrids can successfully serve as controlled release systems for different kinds of antibiotics.

Microgels loaded with gold nanorods: photothermally triggered volume transitions under physiological conditions

Photothermally driven volume transitions in polymer microgels have promising applications for site-specific drug delivery and photodynamic therapy. We studied the temperature-induced volume phase transitions for a series of thermoresponsive microgels of various compositions to find a system with a sharp transition in the physiologically relevant range spanning 38-41 degrees C in 0.01 M phosphate-buffered saline solution (pH = 7.4). We found that the poly(N-isopropylacrylamide-maleic acid) microgels showed an 8-fold decrease in size under the aforementioned conditions. These microgels were loaded with gold nanorods designed to absorb in the near-IR spectral range. Following irradiation at lambda = 809 nm, the microgels underwent a large, reversible, photothermally triggered change in volume. We believe that this microgel system is a promising candidate for photothermally controlled drug release.