Controlled synergistic delivery of paclitaxel and heat from poly(β-amino ester)/iron oxide-based hydrogel nanocomposites

Composite Hydrogels with Included Solid-State Nanoparticles Bearing Anticancer Chemotherapeutics

Hydrogels have many useful physicochemical properties which, in combination with their biocompatibility, suggest their application as a drug delivery system for the local and prorogated release of drugs. However, their drug-absorption capacity is limited because of the gel net's poor adsorption of hydrophilic molecules and in particular, hydrophobic molecules. The absorption capacity of hydrogels can be increased with the incorporation of nanoparticles due to their huge surface area. In this review, composite hydrogels (physical, covalent and injectable) with included hydrophobic and hydrophilic nanoparticles are considered as suitable for use as carriers of anticancer chemotherapeutics. The main focus is given to the surface properties of the nanoparticles (hydrophilicity/hydrophobicity and surface electric charge) formed from metal and dielectric substances: metals (gold, silver), metal-oxides (iron, aluminum, titanium, zirconium), silicates (quartz) and carbon (graphene). The physicochemical properties of the nanoparticles are emphasized in order to assist researchers in choosing appropriate nanoparticles for the adsorption of drugs with hydrophilic and hydrophobic organic molecules.

Poly(β-amino ester) Dual-Drug-Loaded Hydrogels with Antibacterial and Osteogenic Properties for Bone Repair

In this study, we developed a poly(β-amino ester) (PBAE) hydrogel for the double release of vancomycin (VAN) and total flavonoids of Rhizoma Drynariae (TFRD). VAN was covalently bonded to PBAE polymer chains and was released to enhance the antimicrobial effect first. TFRD chitosan (CS) microspheres were physically dispersed in the scaffold, TFRD was released from the microspheres, and osteogenesis was induced subsequently. The scaffold had good porosity (90.12 ± 3.27%), and the cumulative release rate of the two drugs in PBS (pH 7.4) solution exceeded 80%. In vitro antimicrobial assays demonstrated the antibacterial properties of the scaffold against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Besides these, cell viability assays indicated that the scaffold had good biocompatibility. Moreover, alkaline phosphatase and matrix mineralization were expressed more than in the control group. Overall, cell experiments confirmed that the scaffolds have enhanced osteogenic differentiation capabilities. In conclusion, the dual-drug-loaded scaffold with antibacterial and bone regeneration effects is promising in the field of bone repair.

Hyaluronic Acid-Modified Poly-Beta-Amino-Esters for Adriamycin Delivery Against Nasopharyngeal Carcinoma

We developed a delivery system for highly efficient Adriamycin (ADM) use against nasopharyngeal carcinoma (NPC), based on Hyaluronic acid (HA)-poly-beta-amino-esters (PBAE). We used two NPC cell lines, CNE1 and CNE2, and nude mice plated with CNE1 as mouse models for in vitro and in vivo testing of the characteristics and function of ADM@HAPBAE. As a result, the average size of PBAE particles is found to be approximately 100 nm, and ADM@HA-PBAE has stability in environment with changing temperature and at pH = 7.4. In addition, ADM@HA-PBAE could deliver drugs to target lesion with high efficiency and showed high permeability to target areas, facilitating enough ADM release. In NPC cell lines, ADM@HA-PBAE could inhibit cell growth with high efficiency. In NPC mouse model, ADM@HA-PBAE could alleviate NPC growth and development and maintain a healthier physiological status, including body weight recovery, decreased tumor size and NPC inhibition. All these data suggest that ADM@HA-PBAE can increase ADM function by highly efficient targeting and delivery and should be considered as a potential strategy for NPC therapy.

Hydrogels and Hydrogel Nanocomposites: Enhancing Healthcare through Human and Environmental Treatment

Humans are constantly exposed to exogenous chemicals throughout their life, which can lead to a multitude of negative health impacts. Advanced materials can play a key role in preventing or mitigating these impacts through a wide variety of applications. The tunable properties of hydrogels and hydrogel nanocomposites (e.g., swelling behavior, biocompatibility, stimuli responsiveness, functionality, etc.) have deemed them ideal platforms for removal of environmental contaminants, detoxification, and reduction of body burden from exogenous chemical exposures for prevention of disease initiation, and advanced treatment of chronic diseases, including cancer, diabetes, and cardiovascular disease. In this review, three main junctures where the use of hydrogel and hydrogel nanocomposite materials can intervene to positively impact human health are highlighted: 1) preventing exposures to environmental contaminants, 2) prophylactic treatments to prevent chronic disease initiation, and 3) treating chronic diseases after they have developed.

Poly (β amino esters) copolymers: Novel potential vectors for delivery of genes and related therapeutics

The unique properties of polymers have performed an essential contribution to the drug delivery system by providing an outstanding platform for the delivery of macromolecules and genes. However, the block copolymers have been the subject of many recently published works whose results have demonstrated excellent performance in drug targeting. Poly(β-amino esters) (PβAEs) copolymers are the synthetic cationic polymers that are tailored by chemically joining PβAEs with other additives to demonstrate extraordinary efficiency in designing pre-defined and pre-programmed nanostructures, site-specific delivery, andovercoming the distinct cellular barriers. Different compositional and structural libraries could be generated by combinatorial chemistry and by the addition of various novel functional additives that fulfill the multiple requirements of targeted delivery. These intriguing attributes allow PβAE-copolymers to have customized therapeutic functions such as excellent encapsulation capacity, high stability, and stimuli-responsive release. Here, we give an overview of PβAE copolymers-based formulations along with focusing on most notable improvements such as structural modifications, bio-conjugations, and stimuli-responsive approaches, for safe and effective nucleic acids delivery.

Design of Magnetic Hydrogels for Hyperthermia and Drug Delivery

Hydrogels are spatially organized hydrophilic polymeric systems that exhibit unique features in hydrated conditions. Among the hydrogel family, composite hydrogels are a special class that are defined as filler-containing systems with some tailor-made properties. The composite hydrogel family includes magnetic-nanoparticle-integrated hydrogels. Magnetic hydrogels (MHGs) show magneto-responsiveness, which is observed when they are placed in a magnetic field (static or oscillating). Because of their tunable porosity and internal morphology they can be used in several biomedical applications, especially diffusion-related smart devices. External stimuli may influence physical and chemical changes in these hydrogels, particularly in terms of volume and shape morphing. One of the most significant external stimuli for hydrogels is a magnetic field. This review embraces a brief overview of the fabrication of MHGs and two of their usages in the biomedical area: drug delivery and hyperthermia-based anti-cancer activity. As for the saturation magnetization imposed on composite MHGs, they are easily heated in the presence of an alternating magnetic field and the temperature increment is dependent on the magnetic nanoparticle concentration and exposure time. Herein, we also discuss the mode of different therapies based on non-contact hyperthermia heating.

Polyplex-Loaded Hydrogels for Local Gene Delivery to Human Dermal Fibroblasts

Impaired cutaneous healing leading to chronic wounds affects between 2 and 6% of the total population in most developed countries and it places a substantial burden on healthcare budgets. Current treatments involving antibiotic dressings and mechanical debridement are often not effective, causing severe pain, emotional distress, and social isolation in patients for years or even decades, ultimately resulting in limb amputation. Alternatively, gene therapy (such as mRNA therapies) has emerged as a viable option to promote wound healing through modulation of gene expression. However, protecting the genetic cargo from degradation and efficient transfection into primary cells remain significant challenges in the push to clinical translation. Another limiting aspect of current therapies is the lack of sustained release of drugs to match the therapeutic window. Herein, we have developed an injectable, biodegradable and cytocompatible hydrogel-based wound dressing that delivers poly(β-amino ester)s (pBAEs) nanoparticles in a sustained manner over a range of therapeutic windows. We also demonstrate that pBAE nanoparticles, successfully used in previous in vivo studies, protect the mRNA load and efficiently transfect human dermal fibroblasts upon sustained release from the hydrogel wound dressing. This prototype wound dressing technology can enable the development of novel gene therapies for the treatment of chronic wounds.

Current Nanoparticle-Based Technologies for Osteoarthritis Therapy

Osteoarthritis (OA) is a common chronic joint disease that is characterized by joint pain and stiffness, and limitation of motion and the major cause of disability, which reduces life quality of patients and brings a large economic burden to the family and society. Current clinical treatment is mostly limited to symptomatic treatment aimed at pain alleviation and functional improvement, rather than suppressing the progression of OA. Nanotechnology is a promising strategy for the treatment of OA. In this review, we summarize the current experimental progress that focuses on technologies such as liposomes, micelles, dendrimers, polymeric nanoparticles (PNPs), exosomes, and inorganic nanoparticles (NPs) for their potential treatment of OA.

Exploiting Unique Alignment of Cobalt Ferrite Nanoparticles, Mild Hyperthermia, and Controlled Intrinsic Cobalt Toxicity for Cancer Therapy

Nanoparticle-based magnetic hyperthermia is a well-known thermal therapy platform studied to treat solid tumors, but its use for monotherapy is limited due to incomplete tumor eradication at hyperthermia temperature (45 °C). It is often combined with chemotherapy for obtaining a more effective therapeutic outcome. Cubic-shaped cobalt ferrite nanoparticles (Co-Fe NCs) serve as magnetic hyperthermia agents and as a cytotoxic agent due to the known cobalt ion toxicity, allowing the achievement of both heat and cytotoxic effects from a single platform. In addition to this advantage, Co-Fe NCs have the unique ability to form growing chains under an alternating magnetic field (AMF). This unique chain formation, along with the mild hyperthermia and intrinsic cobalt toxicity, leads to complete tumor regression and improved overall survival in an in vivo murine xenograft model, all under clinically approved AMF conditions. Numerical calculations identify magnetic anisotropy as the main Co-Fe NCs' feature to generate such chain formations. This novel combination therapy can improve the effects of magnetic hyperthermia, inaugurating investigation of mechanical behaviors of nanoparticles under AMF, as a new avenue for cancer therapy.

Imparting Functionality to the Hydrogel by Magnetic-Field-Induced Nano-assembly and Macro-response

Hydrogels are composed of 3D hydrophilic networks with an abundance of water; they are analogous to biological soft tissues. Their unique physico-chemical properties endow hydrogels with great potential in many fields, including tissue engineering and flexible sensing. However, inadequate functionality, such as lack of rapid responsiveness, severely limits practical applications in many areas. Therefore, imparting functionality to the hydrogel is a hot research topic. The magnetic field, as an important physical field, provides a new strategy with a variety of advantages. Magnetic-field-induced ordered nano-assembly brought anisotropic properties and novel performance. Furthermore, the magnetic responsiveness of hydrogels with magnetic nanoparticles can lead to the generation of functionality under magnetic fields. Thus, we aim to systematically describe the significant effect of magnetic fields on the functionality of the hydrogel. In this review, magnetic-field-induced assembly of nanomaterials with different dimensions and resulting functional performance are introduced. The functionalities of hydrogels based on magnetic-field-induced macroscopic responses are also summarized. We believe this review will motivate more exploration of the application of magnetic fields to develop functional hydrogel materials.

Development and in vitro evaluation of (β-cyclodextrin-g-methacrylic acid)/Na+-montmorillonite nanocomposite hydrogels for controlled delivery of lovastatin

Background: Hyperlipidemia is the elevation of low density lipoprotein levels resulting in fat deposites in arteries and their hardening and blockage.  It is the leading cause of several life threatening pathological conditions like hypertension, cardiovascular diseases, diabetes etc. Purpose: The objective of this study was to prepare and optimize nontoxic, biocompatible β-CD-g-MAA/Na+-MMT nanocomposite hydrogels with varying content of polymer, monomer and montmorillonite. Moreover, lipid lowering potentials were determined and compared with other approaches. Methods: β-CD-g-MAA/Na+-MMT nanocomposite hydrogels (BM-1 to BM9) were prepared through free radical polymerization by using  β-CD  as polymer, MAA as monomer, MBA as crosslinker and montmorillonite as clay. Developed networks were evaluated for FTIR, DSC, TGA, PXRD, SEM, sol-gel fraction (%), swelling studies, antihyperlipidemic studies and toxicity studies. Results: Optimum swelling (94.24%) and release (93.16%) were obtained at higher pH values. Based on R2 and "n" value LVT release followed zero order kinetics with Super Case II transport release mechanism, respectively. Tensile strength and elongation at break were found to be 0.0283MPa and 94.68%, respectively. Gel fraction was between 80.55 - 98.16%. Antihyperlipidemic studies revealed that LDL levels were markedly reduced from 522.24 ± 21.88mg/dl to 147.63 ± 31.5mg/dl. Toxicity studies assured the safety of developed network. Conclusion: A novel pH responsive crosslinked network containing β-CD - g - poly (methacrylic acid) polymer and MMT was developed and optimized with excellent mechanical, swelling and release properties and lipid lowering potentials.

Evolution of Magnetic Hyperthermia for Glioblastoma Multiforme Therapy

Glioblastoma multiforme (GBM) is the most common and aggressive type of glial tumor, and despite many recent advances, its prognosis remains dismal. Hence, new therapeutic approaches for successful GBM treatment are urgently required. Magnetic hyperthermia-mediated cancer therapy (MHCT), which is based on heating the tumor tissues using magnetic nanoparticles on exposure to an alternating magnetic field (AMF), has shown promising results in the preclinical studies conducted so far. The aim of this Review is to evaluate the progression of MHCT for GBM treatment and to determine its effectiveness on the treatment either alone or in combination with other adjuvant therapies. The preclinical studies presented MHCT as an effective treatment module for the reduction of tumor cell growth and increase in survival of the tumor models used. Over the years, much research has been done to prove MHCT alone as the missing notch for successful GBM therapy. However, very few combinatorial studies have been reported. Some of the clinical studies carried out so far depicted that MHCT could be applied safely while possessing minimal side effects. Finally, we believe that, in the future, advancements in magnetic nanosystems might contribute toward establishing MHCT as a potential treatment tool for glioma therapy.

Poly(β-Amino Esters): Synthesis, Formulations, and Their Biomedical Applications

Poly(β-amino ester) (abbreviated as PBAE or PAE) refers to a polymer synthesized from an acrylate and an amine by Michael addition and has properties inherent to tertiary amines and esters, such as pH responsiveness and biodegradability. The versatility of building blocks provides a library of polymers with miscellaneous physicochemical and mechanical properties. When used alone or together with other materials, PBAEs can be fabricated into different formulations in order to fulfill various requirements in drug delivery (for instance, gene, anticancer drugs, and antimicrobials delivery) and natural complex mimicry (nanochaperones). This progress report discusses the recent developments in design, synthesis, formulations, and applications of PBAEs in biomedical fields and provides a perspective view for the future of the PBAEs.

Preparation and physicochemical characterization of camptothecin conjugated poly amino ester–methyl ether poly ethylene glycol copolymer

In the present study, camptothecin grafted poly amino ester-methyl ether polyethylene glycol (CPT-PEA-MPEG) as a novel copolymer was synthesized by Michael reaction at different ratios of MPEG and CPT (60 : 40 and 80 : 20). The microemulsion was used to prepare nanomicelles, and in vitro cytotoxicity was performed on the HT29 cell line, and cell survival was measured by MTT assay. The syntheses were confirmed by ¹H NMR and FT-IR. Several characterization methods including CMC, particle size, size distribution, and transmission electron microscopy were performed to evaluate features of prepared nanomicelles. Low critical micelle concentration, small particle size and IC₅₀ of 0.1 mg ml⁻¹ at MPEG to CPT ratio of 60 : 40 make this micelle a promising drug delivery carrier. CPT-PAE-MPEG nanomicelles at a MPEG : CPT ratio of 60 : 40 can be a suitable choice to improve the physiochemical properties of CPT and its therapeutic effect, while it can be potentially used as a nano-carrier for other anticancer drugs to purpose a dual drug delivery.

In the present study, camptothecin grafted poly amino ester-methyl ether polyethylene glycol (CPT-PEA-MPEG) as a novel copolymer was synthesized by Michael reaction at different ratios of MPEG and CPT (60 : 40 and 80 : 20).

Degradation of poly(β-amino ester) gels in alcohols through transesterification: A method to conjugate drugs to polymer matrices

Poly(β amino ester) polymers have received growing attention in the literature, owing to their ease of synthesis, versatile co-monomer selection, and highly tunable degradation kinetics. As such, they have shown extensive potential in many biomedical applications as well. In this work, it is demonstrated for the first time that PβAE polymers containing primary and secondary amine groups can undergo degradation by primary alcohols via transesterification mechanism. While this work emphasizes an important aspect of solvent compatibility of these networks, it also represents an interesting, simple mechanism for post synthesis drug incorporation, with riboflavin conjugation being demonstrated as a model compound.

Nanostructured biogel templated synthesis of Fe3O4 nanoparticles and its application for catalytic degradation of xylenol orange

Using jellyfish mesoglea as a natural template, nanocomposite hydrogels with well-dispersed Fe₃O₄ nanoparticles are obtained.

Quercetin conjugated poly(β-amino esters) nanogels for the treatment of cellular oxidative stress

PβAE polymers have emerged as highly promising candidates for biomedical and drug delivery applications owing to their tunable, degradable and pH sensitive properties. These polymeric systems can serve as prodrug carriers for the delivery of bioactive compounds which suffer from poor aqueous solubility, low bioavailability and are biologically unstable, such as the antioxidant, quercetin. Using acrylate functionalized quercetin, it is possible to incorporate the polyphenol into the backbone of the polymer matrix, permitting slow release of the intact molecule which is perfectly timed with the polymer degradation. While formulating these quercetin conjugated PβAE matrix into nanocarriers would allow for multiple delivery routes (oral, intravenous, inhalation etc.), well known oil-water nano-emulsion formulation methods are not amenable to the crosslinked hydrolytically sensitive nanoparticle/nanogel. In this work, a single-phase reaction-precipitation method was developed to formulate quercetin conjugated PβAE nanogels (QNG) via reaction of acrylated quercetin (4-5 acrylate groups) with a secondary diamine under dilute conditions using acetonitrile as the reaction medium, resulting in a self-stabilized suspension. The proposed approach permits the post synthesis modification of the spherical nanogels with a PEGylated coating, enhancing their aqueous stability and stealth characteristics. Nanogel size was controlled by varying feed reactant concentrations, achieving drug loadings of 25-38wt%. Uniform release of quercetin over 45-48h was observed upon PβAE ester hydrolysis under physiological conditions with its retained antioxidant activity over the extended times.

STATEMENT OF SIGNIFICANCE

Here we present the first demonstration of using poly(beta amino ester) chemistry to form nanogels composed of a bioactive polyphenol for the control of cellular oxidative stress. Previous nanogel and nanoparticle approaches, which use a water phase, are not readily amenable to PBAE chemistry due to their hydrolytic sensitivity. Here we demonstrate a simple approach to control particle size, modify surface chemistry and achieve highly regulated controlled release of active antioxidants, which can protect cells against external oxidative stress signals. This work has importance in the area of controlling material biocompatibility through augmenting the antioxidant status of cells.

Magnetic Gel Composites for Hyperthermia Cancer Therapy

Hyperthermia therapy is a medical treatment based on the exposition of body tissue to slightly higher temperatures than physiological (i.e., between 41 and 46 °C) to damage and kill cancer cells or to make them more susceptible to the effects of radiation and anti-cancer drugs. Among several methods suitable for heating tumor areas, magnetic hyperthermia involves the introduction of magnetic micro/nanoparticles into the tumor tissue, followed by the application of an external magnetic field at fixed frequency and amplitude. A very interesting approach for magnetic hyperthermia is the use of biocompatible thermo-responsive magnetic gels made by the incorporation of the magnetic particles into cross-linked polymer gels. Mainly because of the hysteresis loss from the magnetic particles subjected to a magnetic field, the temperature of the system goes up and, once the temperature crosses the lower critical solution temperature, thermo-responsive gels undergo large volume changes and may deliver anti-cancer drug molecules that have been previously entrapped in their networks. This tutorial review describes the main properties and formulations of magnetic gel composites conceived for magnetic hyperthermia therapy.

Efficiency of vanilla, patchouli and ylang ylang essential oils stabilized by iron oxide@C14 nanostructures against bacterial adherence and biofilms formed by Staphylococcus aureus and Klebsiella pneumoniae clinical strains

Biofilms formed by bacterial cells are associated with drastically enhanced resistance against most antimicrobial agents, contributing to the persistence and chronicization of the microbial infections and to therapy failure. The purpose of this study was to combine the unique properties of magnetic nanoparticles with the antimicrobial activity of three essential oils to obtain novel nanobiosystems that could be used as coatings for catheter pieces with an improved resistance to Staphylococcus aureus and Klebsiella pneumoniae clinical strains adherence and biofilm development. The essential oils of ylang ylang, patchouli and vanilla were stabilized by the interaction with iron oxide@C₁₄ nanoparticles to be further used as coating agents for medical surfaces. Iron oxide@C₁₄ was prepared by co-precipitation of Fe⁺² and Fe⁺³ and myristic acid (C₁₄) in basic medium. Vanilla essential oil loaded nanoparticles pelliculised on the catheter samples surface strongly inhibited both the initial adherence of S. aureus cells (quantified at 24 h) and the development of the mature biofilm quantified at 48 h. Patchouli and ylang-ylang essential oils inhibited mostly the initial adherence phase of S. aureus biofilm development. In the case of K. pneumoniae, all tested nanosystems exhibited similar efficiency, being active mostly against the adherence K. pneumoniae cells to the tested catheter specimens. The new nanobiosystems based on vanilla, patchouli and ylang-ylang essential oils could be of a great interest for the biomedical field, opening new directions for the design of film-coated surfaces with anti-adherence and anti-biofilm properties.

Improved small molecule drug release from in situ forming poly(lactic-co-glycolic acid) scaffolds incorporating poly(β-amino ester) and hydroxyapatite microparticles

In situ forming implants are an attractive choice for controlled drug release into a fixed location. Currently, rapidly solidifying solvent exchange systems suffer from a high initial burst, and sustained release behavior is tied to polymer precipitation and degradation rate. The present studies investigated addition of hydroxyapatite (HA) and drug-loaded poly(β-amino ester) (PBAE) microparticles to in situ forming poly(lactic-co-glycolic acid) (PLGA)-based systems to prolong release and reduce burst. PBAEs were synthesized, imbibed with simvastatin (osteogenic) or clodronate (anti-resorptive), and then ground into microparticles. Microparticles were mixed with or without HA into a PLGA solution, and the mixture was injected into buffer, leading to precipitation and creating solid scaffolds with embedded HA and PBAE microparticles. Simvastatin release was prolonged through 30 days, and burst release was reduced from 81 to 39% when loaded into PBAE microparticles. Clodronate burst was reduced from 49 to 32% after addition of HA filler, but release kinetics were unaffected after loading into PBAE microparticles. Scaffold dry mass remained unchanged through day 15, with a pronounced increase in degradation rate after day 30, while wet scaffolds experienced a mass increase through day 25 due to swelling. Porosity and pore size changed throughout degradation, likely due to a combination of swelling and degradation. The system offers improved release kinetics, multiple release profiles, and rapid solidification compared to traditional in situ forming implants.

A magnetic nanogel based on O-carboxymethylchitosan for antitumor drug delivery: synthesis, characterization and in vitro drug release

This paper studied the synthesis, characterization and use of the magnetic chitosan nanogel for carrying meleimidic compounds. The hydrogel polymer was prepared using O-carboxymethylchitosan, which was crosslinked with epichlorohydrin for subsequent incorporation of iron oxide magnetic nanoparticles. The characterization revealed that the magnetic material comprises about 10% of the hydrogel. This material is comprised of magnetite and maghemite and exhibits ferro-ferrimagnetic behavior. The average particle size is 4.2 nm. There was high incorporation efficiency of maleimides in the magnetic nanogel. The release was of sustained character and there was a greater release when an external magnetic field was applied. The mathematical model that best explained the process of drug release by the magnetic hydrogel was that of Peppas-Sahlin. The magnetic nanogel proved to be an excellent candidate for use in drug-delivery systems.

Mechanical properties and dual drug delivery application of poly(lactic-co-glycolic acid) scaffolds fabricated with a poly(β-amino ester) porogen

Polymeric scaffolds that are biocompatible and biodegradable are widely used for tissue engineering applications. Scaffolds can be further enhanced by enabling the release of one or more drugs to stimulate regeneration or for the treatment of a specific disease or condition. In this study, poly(lactic-co-glycolic acid) (PLGA) microspheres were mixed with poly(β-amino ester) (PBAE) particles to create novel hybrid scaffolds capable of dual release of drug and growth factor. Fast-degrading PBAE particles loaded with the drug ketoprofen acted as porogens that provided a rapid 12h release. The PLGA microspheres were loaded with a growth factor, bone morphogenetic protein 2, and fused together around the porogens to create a slow-degrading matrix that provided sustained release lasting 70days. Drug release was further tailored by varying the amount of porogen added to the scaffold. Bioactivity measurements demonstrated that the scaffold fabrication technique did not damage the drug or protein. The compressive modulus was affected by the amount of porogen added, extending from 50 to 111MPa for loadings from 60 to 40% PBAE, and after 5days of degradation, it decreased to 0.6 to 1.1kPa when the porogen was gone. PLGA containing a quick-degrading porogen can be used to release two drugs while developing a porous microarchitecture for cell ingrowth with in a matrix capable of maintaining a compressive modulus applicable for soft tissue implants.

Hydrogels in Healthcare: From Static to Dynamic Material Microenvironments

Advances in hydrogel design have revolutionized the way biomaterials are applied to address biomedical needs. Hydrogels were introduced in medicine over 50 years ago and have evolved from static, bioinert materials to dynamic, bioactive microenvironments, which can be used to direct specific biological responses such as cellular ingrowth in wound healing or on-demand delivery of therapeutics. Two general classes of mechanisms, those defined by the user and those dictated by the endogenous cells and tissues, can control dynamic hydrogel microenvironments. These highly tunable materials have provided bioengineers and biological scientists with new ways to not only treat patients in the clinic but to study the fundamental cellular responses to engineered microenvironments as well. Here, we provide a brief history of hydrogels in medicine and follow with a discussion of the synthesis and implementation of dynamic hydrogel microenvironments for healthcare-related applications.