High-Throughput Synthesis and Screening of Rapidly Degrading Polyanhydride Nanoparticles.

Combinatorial techniques can accelerate the discovery and development of polymeric nanodelivery devices by pairing high-throughput synthesis with rapid materials characterization. Biodegradable polyanhydrides demonstrate tunable release, high cellular internalization, and dose sparing properties when used as nanodelivery devices. This nanoparticle platform shows promising potential for small molecule drug delivery, but the pace of understanding and rational design of these nanomedicines is limited by the low throughput of conventional characterization. This study reports the use of a high-throughput method to synthesize libraries of a newly synthesized, rapidly eroding polyanhydride copolymer based on 1,8-bis(p-carboxyphenoxy)-3,6-dioxaoctane (CPTEG) and sebacic acid (SA) monomers. The high-throughput method enabled efficient screening of copolymer microstructure, revealing weak block-type and alternating architectures. The high-throughput method was adapted to synthesize nanoparticle libraries encapsulating hydrophobic model drugs. Drug release from these nanoparticles was rapid, with a majority of the payload released within 3 days. Drug release was dramatically slowed at acidic pH, which could be useful for oral drug delivery. Rhodamine B (RhoB) release kinetics generally followed patterns of polymer erosion kinetics, while Coomassie brilliant blue (CBB) released the fastest from the slowest degrading polymer chemistry and vice versa. These differences in trends between copolymer chemistry and release kinetics were hypothesized to arise from differences in mixing thermodynamics. A high-throughput method was developed to synthesize polymer-drug film libraries and characterize mixing thermodynamics by melting point depression. Rhodamine B had a negative χ for all copolymers with <30 mol % CPTEG tested, indicating a tendency toward miscibility. By contrast, CBB χ increased, eventually becoming positive near 15:85 CPTEG:SA, with increasing CPTEG content. This indicates an increasing tendency toward phase separation in CPTEG-rich copolymers. These in vitro results screening polymer-drug interactions showed good agreement with in silico predictions from Hansen solubility parameter estimation and were able to explain the observed differences in model drug release trends.

Recent Advances in Polyanhydride Based Biomaterials.

This review focusses on recent developments of polyanhydrides, a class of degradable synthetic biopolymers. Polyanhydrides have been used as carriers for controlled delivery of drugs. A polyanhydride copolymer of carboxyphenoxy propane and sebacic acid has been used in Gliadel brain tumor implants for the controlled delivery of carmustine or bis-chloroethylnitrosourea. They are easy and inexpensive to synthesize (especially scale up). However, polyanhydrides possess a short shelf-life. Hydrolytic cleavage and anhydride interchanges lower their molecular weights during storage. One of the highlights in recent developments of polyanhydride chemistry is the discovery of alternating copolymers having extended shelf-life. Other highlights include their applications in biomedical electronics, vaccine delivery, and nano/micro particulate delivery systems. This review examines approaches for polyanhydride synthesis followed by their recent developments in biomedical applications.

Automated High-Throughput Synthesis of Protein-Loaded Polyanhydride Nanoparticle Libraries.

The development of high-throughput techniques and combinatorial libraries can facilitate rapid synthesis and screening of biomaterial-based nanocarriers for drug and vaccine delivery. This study describes a high-throughput method using an automated robot for synthesizing polyanhydride nanoparticles encapsulating proteins. Polyanhydrides are a class of safe and biodegradable polymers that have been widely used as drug and vaccine delivery vehicles. The robot contains a multiplexed homogenizer and has the capacity to handle parallel streams of monomer or polymer solutions to synthesize polymers and/or nanoparticles. Copolymer libraries were synthesized using the monomers sebacic acid, 1,6-bis( p-carboxyphenoxy)hexane, and 1,8-bis( p-carboxyphenoxy)-3,6-dioxactane and compared to conventionally synthesized copolymers. Nanoparticle libraries of varying copolymer compositions encapsulating the model antigen ovalbumin were synthesized using flash nanoprecipitation. The amount of the surfactant Span 80 was varied to test its effect on protein encapsulation efficiency as well as antigen release kinetics. It was observed that, although the amount of surfactant did not significantly affect protein release rate, its presence enhanced protein encapsulation efficiency. Protein burst and release kinetics from conventionally and combinatorially synthesized nanoparticles were similar even though particles synthesized using the high-throughput technique were smaller. Finally, it was demonstrated that the high-throughput method could be adapted to functionalize the surface of particle libraries to aid in the design and screening of targeted drug and vaccine delivery systems. These results suggest that the new high-throughput method is a viable alternative to conventional methods for synthesizing and screening protein and vaccine delivery vehicles.

pH-Responsive Microencapsulation Systems for the Oral Delivery of Polyanhydride Nanoparticles.

Multicompartmental polymer carriers, referred to as Polyanhydride-Releasing Oral MicroParticle Technology (PROMPT), were formed by a pH-triggered antisolvent precipitation technique. Polyanhydride nanoparticles were encapsulated into anionic pH-responsive microparticle gels, allowing for nanoparticle encapsulation in acidic conditions and subsequent release in neutral pH conditions. The effects of varying the nanoparticle composition and feed ratio on the encapsulation efficiency were evaluated. Nanoparticle encapsulation was confirmed by confocal microscopy and infrared spectroscopy. pH-triggered protein delivery from PROMPT was explored using ovalbumin (ova) as a model drug. PROMPT microgels released ova in a pH-controlled manner. Increasing the feed ratio of nanoparticles into the microgels increased the total amount of ova delivered, as well as decreased the observed burst release. The cytocompatibility of the polymer materials were assessed using cells representative of the GI tract. Overall, these results suggest that pH-dependent microencapsulation is a viable platform to achieve targeted intestinal delivery of polyanhydride nanoparticles and their payload(s).

Stable polyanhydride synthesized from sebacic acid and ricinoleic acid.

Poly(anhydride) are unstable and prone to hydrolytic degradation and depolymerisation via anhydride interchange. They are stored at -20°C, packed under inert atmosphere until use. We synthesized a new poly(anhydride) from ricinoleic (RA) and sebacic (SA) acid with alternating ester-anhydride structure that is stable at 25°C for over 18months. The copolymer is also stable in chloroform solution and under γ-irradiation. The polymer hydrolyses through anhydride cleavage lasting ~7days to form oligoesters, which are stable for >30days. The release of gentamycin from the synthesized alternate polymer matrix is sustained compared to the random copolymer.

Effect of nanovaccine chemistry on humoral immune response kinetics and maturation.

Acute respiratory infections represent a significant portion of global morbidity and mortality annually. There is a critical need for efficacious vaccines against respiratory pathogens. To vaccinate against respiratory disease, pulmonary delivery is an attractive route because it mimics the route of natural infection and can confer both mucosal and systemic immunity. We have previously demonstrated that a single dose, intranasal vaccine based on polyanhydride nanoparticles elicited a protective immune response against Yersinia pestis for at least 40 weeks after immunization with F1-V. Herein, we investigate the effect of nanoparticle chemistry and its attributes on the kinetics and maturation of the antigen-specific serum antibody response. We demonstrate that manipulation of polyanhydride nanoparticle chemistry facilitated differential kinetics of development of antibody titers, avidity, and epitope specificity. The results provide new insights into the underlying role(s) of nanoparticle chemistry in providing long-lived humoral immunity and aid in the rational design of nanovaccine formulations to induce long-lasting and mature antibody responses.

Photopolymerized cross-linked thiol-ene polyanhydrides: erosion, release, and toxicity studies.

Several critical aspects of cross-linked polyanhydrides made using thiol-ene polymerization are reported, in particular the erosion, release, and solution properties, along with their cytotoxicity toward fibroblast cells. The monomers used to synthesize these polyanhydrides were 4-pentenoic anhydride and pentaerythritol tetrakis(3-mercaptopropionate). Techniques used to evaluate the erosion mechanism indicate a complex situation in which several phenomena, such as hydrolysis rates, local pH, water diffusion, and solubility, may be influencing the erosion process. The mass loss profile, the release rate of a hydrophilic dye, the rate of hydrolysis of the polyanhydride, the hydrolysis product solubility as a function of pH, average pK(a) and its cytotoxicity toward fibroblast cells were all determined. The solubility of the degradation product is low at pH values less than 6-7, and the average pKa was determined to be ~5.3. The cytotoxicity of the polymer and the degradation product was found to be low, with cell viabilities of >97% for the various samples studied at concentrations of ~1000-1500 ppm. These important parameters help determine the potential of the thiol-ene polyanhydrides in various biomedical applications. These polyanhydrides can be used as a delivery vehicle, and although the release profile qualitatively followed the mass loss profile for a hydrophilic dye, the release rate appears to be by both diffusion and mass loss mechanisms.

Poly(anhydride-esters) comprised exclusively of naturally occurring antimicrobials and EDTA: antioxidant and antibacterial activities.

Carvacrol, thymol, and eugenol are naturally occurring phenolic compounds known to possess antimicrobial activity against a range of bacteria, as well as antioxidant activity. Biodegradable poly(anhydride-esters) composed of an ethylenediaminetetraacetic acid (EDTA) backbone and antimicrobial pendant groups (i.e., carvacrol, thymol, or eugenol) were synthesized via solution polymerization. The resulting polymers were characterized to confirm their chemical composition and understand their thermal properties and molecular weight. In vitro release studies demonstrated that polymer hydrolytic degradation was complete after 16 days, resulting in the release of free antimicrobials and EDTA. Antioxidant and antibacterial assays determined that polymer release media exhibited bioactivity similar to that of free compound, demonstrating that polymer incorporation and subsequent release had no effect on activity. These polymers completely degrade into components that are biologically relevant and have the capability to promote preservation of consumer products in the food and personal care industries via antimicrobial and antioxidant pathways.

Preparation and in vitro evaluation of novel poly(anhydride-ester)-based amphiphilic copolymer curcumin-loaded micelles.

Novel poly(anhydride-ester)-b-poly(ethylene glycol) copolymers (PAE-b-PEGs) were synthesized by esterization of methyl poly(ethylene glycol) and poly(anhydride-ester), which were obtained by the melt polycondensation of alpha,omega-acetic anhydride-terminated poly(L-lactic acid), and characterized by 1H-NMR and gel permeation chromatography. The two poly(anhydride-ester)-b-poly(ethylene glycols) (denoted as PAE-b-PEG2k and PAE-b-PEG5k) thus obtained can self-assemble in water to form micelles with hydrodynamic diameters of 92.5 and 97.5 nm above their critical micelle concentrations of 3.78 and 2.36 microg/mL, respectively. The curcumin-loaded PAE-b-PEG2k and PAE-b-PEG5k micelles were prepared by the solid dispersion method, and they could encapsulate approximately 7% (w/w) curcumin. The diameters of the micelles were stable for 5 days. Curcumin is released faster from the micelles at pH 5.0 than at pH 7.4. Curcumin is released from the micelles at a fast rate during the initial 12 h, followed by a zero-order release during the subsequent 200 h, both at pH 5.0 and 7.4. The IC50 values of the curcumin-loaded PAE-b-PEG2k and PAE-b-PEG5k micelles against HeLa cells are 12.41 and 15.31 microg/mL, respectively, which is lower than that of free curcumin (25.90 microg/mL). The PAE-b-PEG2k micelles are taken up faster than the PAE-b-PEG5k micelles by HeLa cells. Curcumin-loaded micelles can induce G2/M phase cell cycle arrest and apoptosis of HeLa cells.

Combinatorial Synthesis of and high-throughput protein release from polymer film and nanoparticle libraries.

Polyanhydrides are a class of biomaterials with excellent biocompatibility and drug delivery capabilities. While they have been studied extensively with conventional one-sample-at-a-time synthesis techniques, a more recent high-throughput approach has been developed enabling the synthesis and testing of large libraries of polyanhydrides(1). This will facilitate more efficient optimization and design process of these biomaterials for drug and vaccine delivery applications. The method in this work describes the combinatorial synthesis of biodegradable polyanhydride film and nanoparticle libraries and the high-throughput detection of protein release from these libraries. In this robotically operated method (Figure 1), linear actuators and syringe pumps are controlled by LabVIEW, which enables a hands-free automated protocol, eliminating user error. Furthermore, this method enables the rapid fabrication of micro-scale polymer libraries, reducing the batch size while resulting in the creation of multivariant polymer systems. This combinatorial approach to polymer synthesis facilitates the synthesis of up to 15 different polymers in an equivalent amount of time it would take to synthesize one polymer conventionally. In addition, the combinatorial polymer library can be fabricated into blank or protein-loaded geometries including films or nanoparticles upon dissolution of the polymer library in a solvent and precipitation into a non-solvent (for nanoparticles) or by vacuum drying (for films). Upon loading a fluorochrome-conjugated protein into the polymer libraries, protein release kinetics can be assessed at high-throughput using a fluorescence-based detection method (Figures 2 and 3) as described previously(1). This combinatorial platform has been validated with conventional methods(2) and the polyanhydride film and nanoparticle libraries have been characterized with (1)H NMR and FTIR. The libraries have been screened for protein release kinetics, stability and antigenicity; in vitro cellular toxicity, cytokine production, surface marker expression, adhesion, proliferation and differentiation; and in vivo biodistribution and mucoadhesion(1-11). The combinatorial method developed herein enables high-throughput polymer synthesis and fabrication of protein-loaded nanoparticle and film libraries, which can, in turn, be screened in vitro and in vivo for optimization of biomaterial performance.

High-throughput synthesis of carbohydrates and functionalization of polyanhydride nanoparticles.

Transdisciplinary approaches involving areas such as material design, nanotechnology, chemistry, and immunology have to be utilized to rationally design efficacious vaccines carriers. Nanoparticle-based platforms can prolong the persistence of vaccine antigens, which could improve vaccine immunogenicity. Several biodegradable polymers have been studied as vaccine delivery vehicles(1); in particular, polyanhydride particles have demonstrated the ability to provide sustained release of stable protein antigens and to activate antigen presenting cells and modulate immune responses. The molecular design of these vaccine carriers needs to integrate the rational selection of polymer properties as well as the incorporation of appropriate targeting agents. High throughput automated fabrication of targeting ligands and functionalized particles is a powerful tool that will enhance the ability to study a wide range of properties and will lead to the design of reproducible vaccine delivery devices. The addition of targeting ligands capable of being recognized by specific receptors on immune cells has been shown to modulate and tailor immune responses. C-type lectin receptors (CLRs) are pattern recognition receptors (PRRs) that recognize carbohydrates present on the surface of pathogens. The stimulation of immune cells via CLRs allows for enhanced internalization of antigen and subsequent presentation for further T cell activation. Therefore, carbohydrate molecules play an important role in the study of immune responses; however, the use of these biomolecules often suffers from the lack of availability of structurally well-defined and pure carbohydrates. An automation platform based on iterative solution-phase reactions can enable rapid and controlled synthesis of these synthetically challenging molecules using significantly lower building block quantities than traditional solid-phase methods. Herein we report a protocol for the automated solution-phase synthesis of oligosaccharides such as mannose-based targeting ligands with fluorous solid-phase extraction for intermediate purification. After development of automated methods to make the carbohydrate-based targeting agent, we describe methods for their attachment on the surface of polyanhydride nanoparticles employing an automated robotic set up operated by LabVIEW as previously described. Surface functionalization with carbohydrates has shown efficacy in targeting CLRs and increasing the throughput of the fabrication method to unearth the complexities associated with a multi-parametric system will be of great value (Figure 1a).

"Click" synthesis of fatty acid derivatives as fast-degrading polyanhydride precursors.

Fast-degrading linear and branched polyanhydrides are obtained by melt-condensation of novel di- and tri-carboxylic acid monomers based on oleic and undecylenic acid synthesized using photoinitiated thiol-ene click chemistry. (1)H NMR spectroscopy, size exclusion chromatography, differential scanning calorimetry, thermogravimetric analysis, and FT-IR spectroscopy have been used to fully characterize these polymers. The hydrolytic degradation of these polymers was studied by means of weight loss, anhydride bond loss, and changes in molecular weight, showing fast degrading properties. Drug release studies from the synthesized polyanhydrides have also been conducted, using rhodamine B as a hydrophobic model drug, to evaluate the potential of these polymers in biomedical applications.

Polyanhydride microparticles enhance dendritic cell antigen presentation and activation.

The present study was designed to evaluate the adjuvant activity of polyanhydride microparticles prepared in the absence of additional stabilizers, excipients or immune modulators. Microparticles composed of varying ratios of either 1,6-bis(p-carboxyphenoxy)hexane (CPH) and sebacic acid or 1,8-bis(p-carboxyphenoxy)-3,6-dioxaoctane and CPH were added to in vitro cultures of bone marrow-derived dendritic cells (DCs). Microparticles were efficiently and rapidly phagocytosed by DCs in the absence of opsonization and without centrifugation or agitation. Within 2h, internalized particles were rapidly localized to an acidic, phagolysosomal compartment. By 48 h, only a minor reduction in microparticle size was observed in the phagolysosomal compartment, indicating minimal particle erosion consistent with being localized within an intracellular microenvironment favoring particle stability. Polyanhydride microparticles increased DC surface expression of major histocompatability complex class II, the co-stimulatory molecules CD86 and CD40, and the C-type lectin CIRE (murine DC-SIGN; CD209). In addition, microparticle stimulation of DCs also enhanced secretion of the cytokines IL-12p40 and IL-6, a phenomenon found to be dependent on polymer chemistry. DCs cultured with polyanhydride microparticles and ovalbumin induced polymer chemistry-dependent antigen-specific proliferation of both CD4(+) OT-II and CD8(+) OT-I T cells. These data indicate that polyanhydride particles can be tailored to take advantage of the potential plasticity of the immune response, resulting in the ability to induce immune protection against many types of pathogens.

Preparation and characterization of biodegradable electrospun polyanhydride nano/microfibers.

The biodegradable polyanhydride copolymers P(CPP-SA) composed of p-carboxyhenoxy propane (CPP) and sebacic acid (SA) at weight ratios of 20:80, 35:65 and 50:50 were polymerized by a melt polycondensation process without catalyst. The copolymers were characterized by fourier transform infrared spectroscopy (FT-IR), 1H-nuclear magnetic resonance (1H-NMR), Ubbelohde viscometer, differential scanning calorimetry (DSC) and wide angle X-ray powder-diffraction (XRD). P(CPP-SA) nano/microfibers were the first time to be fabricated by electrospinning. The copolymers hold an excellent fibre-forming performance and the diameter range of 80-3,200 nm can be obtained. The in vitro degradation of the polyanhydride copolymers was evaluated in form of the nano/microfibers by investigating the change of fibrous morphology, weight loss and pH change of degradation medium. The experimental results showed that degradation rate was fast in the fist day and slow in the following period, furthermore the degradation rate decreased with the increase of the content of CPP in copolymers. Therefore, the electrospun polyanhydride nano/microfibers exhibited strong potential as drug delivery vehicle and tissue engineering scaffold.

Effect of polymer chemistry and fabrication method on protein release and stability from polyanhydride microspheres.

The release kinetics and stability of ovalbumin encapsulated into polyanhydride microspheres with varying chemistries were studied. Polymers based on the anhydride monomers sebacic acid (SA), 1,6-bis(p-carboxyphenoxy)hexane (CPH), and 1,8-bis (p-carboxyphenoxy)-3,6-dioxaoctane (CPTEG) were utilized. Microspheres were fabricated using two non-aqueous methods: a solid/oil/oil double emulsion technique and cryogenic atomization. The studies showed that the two fabrication methods did not significantly affect the release kinetics of ovalbumin, even though the burst release of the protein was a function of the fabrication method and the polymer chemistry. Antigenic stability of ovalbumin released from microspheres prepared by cryogenic atomization was studied by western blot analysis. These studies indicate that the amphiphilic CPTEG:CPH polyanhydrides preserved protein structure and enhanced protein stability by preserving the immunological epitopes of released protein.

Preparation and characterization of protein-loaded polyanhydride microspheres.

Poly(1,3-bis-(p-carboxyphenoxy propane)-co-(sebacic anhydride) (P(CPP-SA)) have the anhydride bonds in copolymer backbone, which are available for degradation on the base of passive hydrolysis. This chemical structure made it degraded within a short time in linear degradation rate. For this property, polyanhydrides are one of the most suitable biodegradable polymers employed as drug carriers. This paper aimed at researching the erosion and degradation of P(CPP-SA) microspheres with CPP/SA monomer ratios of 20:80, 35:65 and 50:50. In vitro protein release from the microspheres was also investigated in this paper. Human serum albumin (HSA) was used as the model protein. In this research, the microspheres degradation and drug release rate from microspheres can be adjusted by altering the CPP/SA ratios of P(CPP-SA). The features of surface erosion were observed in SEM. The structural integrity of HSA extracted from microspheres was detected by gel permeation chromatography, compared with native HSA. The results showed HSA remained its molecule weight after encapsulated.

Polymer chemistry influences monocytic uptake of polyanhydride nanospheres.

PURPOSE: To demonstrate that polyanhydride copolymer chemistry affects the uptake and intracellular compartmentalization of nanospheres by THP-1 human monocytic cells. METHODS: Polyanhydride nanospheres were prepared by an anti-solvent nanoprecipitation technique. Morphology and particle diameter were confirmed via scanning election microscopy and quasi-elastic light scattering, respectively. The effects of varying polymer chemistry on nanosphere and fluorescently labeled protein uptake by THP-1 cells were monitored by laser scanning confocal microscopy. RESULTS: Polyanhydride nanoparticles composed of poly(sebacic anhydride) (SA), and 20:80 and 50:50 copolymers of 1,6-bis-(p-carboxyphenoxy)hexane (CPH) anhydride and SA were fabricated with similar spherical morphology and particle diameter (200 to 800 nm). Exposure of the nanospheres to THP-1 monocytes showed that poly(SA) and 20:80 CPH:SA nanospheres were readily internalized whereas 50:50 CPH:SA nanospheres had limited uptake. The chemistries also differentially enhanced the uptake of a red fluorescent protein-labeled antigen. CONCLUSIONS: Nanosphere and antigen uptake by monocytes can be directly correlated to the chemistry of the nanosphere. These results demonstrate the importance of choosing polyanhydride chemistries that facilitate enhanced interactions with antigen presenting cells that are necessary in the initiation of efficacious immune responses.

Iodinated salicylate-based poly(anhydride-esters) as radiopaque biomaterials.

Poly(anhydride-esters) based on iodinated versions of salicylic acid were synthesized via both melt-condensation and solution polymerization techniques to generate radiopaque biomaterials. The poly(anhydride-esters) from iodinated salicylates were highly X-ray opaque compared to poly(anhydride-esters) from salicylic acid. Molecular weight and Young's modulus of polymers prepared by melt-condensation were typically two-to-three times higher than polymers prepared by solution methods. The glass transition temperatures of the polymers were dependent on the iodine concentration; polymers containing more iodine had higher glass transition temperatures. Cytotoxicity studies using mouse fibroblasts indicated that iodinated salicylate-based poly(anhydride-esters) prepared by both polymerization methods are biocompatible with cells at low polymer concentrations (0.01 mg/mL).

Salicylic acid-based poly(anhydride esters) for control of biofilm formation in Salmonella enterica serovar Typhimurium.

AIMS: Bacterial biofilms generally are more resistant to stresses as compared with free planktonic cells. Therefore, the discovery of antimicrobial stress factors that have strong inhibitory effects on bacterial biofilm formation would have great impact on the food, personal care, and medical industries. METHODS AND RESULTS: Salicylate-based poly(anhydride esters) (PAE) have previously been shown to inhibit biofilm formation, possibly by affecting surface attachment. Our research evaluated the effect of salicylate-based PAE on biofilm-forming Salmonella enterica serovar Typhimurium. To remove factors associated with surface physical and chemical parameters, we utilized a strain that forms biofilms at the air-liquid interface. Surface properties can influence biofilm characteristics, so the lack of attachment to a solid surface eliminates those constraints. The results indicate that the salicylic acid-based polymers do interfere with biofilm formation, as a clear difference was seen between bacterial strains that form biofilms at the air-liquid interface (top-forming) and those that form at the surface-liquid interface (bottom-forming). CONCLUSION: These results lead to the conclusion that the polymers may not interfere with attachment; rather, the polymers likely affect another mechanism essential for biofilm formation in Salmonella. SIGNIFICANCE AND IMPACT OF THE STUDY: Biofilm formation can be prevented through controlled release of nature-derived antimicrobials formulated into polymer systems.

Hydroxy fatty acid based polyanhydride as drug delivery system: synthesis, characterization, in vitro degradation, drug release, and biocompatibility.

Low molecular weight hydroxy fatty acid based polyanhydrides were synthesized by one pot method, a variable of typical melt-condensation and characterized by FTIR, NMR, DSC, and GPC. Polymer degrades by both surface and bulk erosion as trailed by weight loss, anhydride loss and surface morphology. Control over drug release was accessed with drugs featuring different aqueous solubility, that is, methotrexate (hydrophobic) and 5-fluorouracil (hydrophilic). Effect of loading, at 5, 10, and 20% w/w of methotrexate on release profiles was also studied and negligible effect was discovered. Biocompatibility of polymers was evaluated in SD rats after SC injection of the polymer. Histopathology revealed initial inflammation of the tissues near the injection site however healed with time. Overall, these polymers were found good to control the release of the entrapped drug and were found biocompatible in preliminary in vivo study. Due to their low melting temperatures they can be injected locally (SC or intratumorally) to from regional in situ depot and have a great potential as a drug carrier for localized delivery of anticancer drugs.