Cyclopropenimine-Mediated CO2 Activation for the Synthesis of Polyurethanes and Small-Molecule Carbonates and Carbamates.

Carbon dioxide (CO2) is an abundant C1 feedstock with tremendous potential to produce versatile building blocks in synthetic applications. Given the adverse impact of CO2 on the atmosphere, it is of paramount importance to devise strategies for upcycling it into useful materials, such as polymers and fine chemicals. To activate such stable molecule, superbases offer viable modes of binding to CO2. In this study, a superbase cyclopropenimine derivative was found to exhibit exceptional proficiency in activating CO2 and mediating its polymerization at ambient temperature and pressure for the synthesis of polyurethanes. The versatility of this reaction can be extended to monofunctional amines and alcohols, yielding a variety of functional carbonates and carbamates.

Ring-Opening Polymerization of Cyclic Esters and Carbonates with (Thio)urea/Cyclopropenimine Organocatalytic Systems.

Organocatalyzed ring-opening polymerization is a powerful tool for the synthesis of a variety of functional, readily degradable polyesters and polycarbonates. We report the use of (thio)ureas in combination with cyclopropenimine bases as a unique catalyst for the polymerization of cyclic esters and carbonates with a large span of reactivities. Methodologies of exceptionally effective and selective cocatalyst combinations were devised to produce polyesters and polycarbonates with narrow dispersities (D = 1.01-1.10). Correlations of the pKa of the various ureas and cyclopropenimine bases revealed the critical importance of matching the pKa of the two cocatalysts to achieve the most efficient polymerization conditions. It was found that promoting strong H-bonding interactions with a noncompetitive organic solvent, such as CH2Cl2, enabled greatly increased polymerization rates. The stereoselective polymerization of rac-lactide afforded stereoblock poly(lactides) that crystallize as stereocomplexes, as confirmed by wide-angle X-ray scattering.

pH-Responsive Polymeric Micelle Dynamic Complexes for Selective Killing of Helicobacter pylori.

Helicobacter pylori, the world's most common chronic infection-causing pathogen, is responsible for causing gastric ulcers, the fourth-leading cause of cancer-related death globally in 2020. In recent years, the effectiveness of the current treatment regimen (two antibiotics and one proton pump inhibitor) has often been plagued with problems such as resistance and the undesired elimination of commensal bacteria. Herein, we report the synthesis of block and random copolycarbonates, functionalized with cationic guanidinium and anionic acetate functional groups, aimed at selectively killing H. pylori in the acidic environment of the stomach, while remaining nontoxic to the commensal bacteria in the gut. The compositions of the polymers were fine-tuned so that the polymers were readily dispersed in water without any difficulty at both pH 3.0 and 7.4. The self-assembly behavior of the polymers at different pH values by dynamic light scattering showed that the random and block copolymers formed stable micelles in a simulated gastric environment (pH 3.0) while aggregated at pH 7.4. Both polymers demonstrated stronger antibacterial activity against H. pylori than the guanidinium-functionalized homopolymer without any acetate functional group at pH 3.0. The block copolymer was significantly more bactericidal at pH 3.0 across the concentrations tested, as compared to the random copolymer, while it did not show significant toxicity toward rat red blood cells (rRBCs) and HK-2 cells or bactericidal effect toward E. coli (a common gut bacterium) and nor caused aggregation of rRBCs at its effective concentration and at physiological pH of 7.4. Additionally, both the block and random copolymers were much more stable against hydrolysis at pH 3.0 than at pH 7.4. This study provides insight into the influence of both polymer architecture and dynamic assembly on the bioactivities of antimicrobial polymers, where the disassembly of coacervates into narrowly dispersed micelles at pH 3 make them potent antimicrobials aided by the protonated carboxylic acid block.

Artificial intelligence driven design of catalysts and materials for ring opening polymerization using a domain-specific language.

Advances in machine learning (ML) and automated experimentation are poised to vastly accelerate research in polymer science. Data representation is a critical aspect for enabling ML integration in research workflows, yet many data models impose significant rigidity making it difficult to accommodate a broad array of experiment and data types found in polymer science. This inflexibility presents a significant barrier for researchers to leverage their historical data in ML development. Here we show that a domain specific language, termed Chemical Markdown Language (CMDL), provides flexible, extensible, and consistent representation of disparate experiment types and polymer structures. CMDL enables seamless use of historical experimental data to fine-tune regression transformer (RT) models for generative molecular design tasks. We demonstrate the utility of this approach through the generation and the experimental validation of catalysts and polymers in the context of ring-opening polymerization-although we provide examples of how CMDL can be more broadly applied to other polymer classes. Critically, we show how the CMDL tuned model preserves key functional groups within the polymer structure, allowing for experimental validation. These results reveal the versatility of CMDL and how it facilitates translation of historical data into meaningful predictive and generative models to produce experimentally actionable output.

Nanocomplexes of Biodegradable Anticancer Macromolecules: Prolonged Plasma Half-Life, Reduced Toxicity, and Increased Tumor Targeting.

Anticancer drug resistance is a large contributing factor to the global mortality rate of cancer patients. Anticancer macromolecules such as polymers have been recently reported to overcome this issue. Anticancer macromolecules have unselective toxicity because they are highly positively charged. Herein, an anionic biodegradable polycarbonate carrier is synthesized and utilized to form nanocomplexes with an anticancer polycarbonate via self-assembly to neutralize its positive charges. Biotin is conjugated to the anionic carrier and serves as cancer cell-targeting moiety. The nanoparticles have sizes of < 130 nm with anticancer polymer loading levels of 38-49%. Unlike the small molecular anticancer drug doxorubicin, the nanocomplexes effectively inhibit the growth of both drug-susceptible MCF7 and drug-resistant MCF7/ADR human breast cancer cell lines with low half maximal inhibitory concentration (IC50 ). The nanocomplexes increase the anticancer polymer's in vivo half-life from 1 to 6-8 h, and rapidly kill BT474 human breast cancer cells primarily via an apoptotic mechanism. The nanocomplexes significantly increase the median lethal dose (LD50 ) and reduce the injection site toxicity of the anticancer polymer. They suppress tumor growth by 32-56% without causing any damage to the liver and kidneys. These nanocomplexes may potentially be used for cancer treatment to overcome drug resistance.

Pharmacokinetics of ciprofloxacin and fluocinolone acetonide otic solution in pediatric patients.

PURPOSE: To describe the pharmacokinetics (PK) of ciprofloxacin 0.3 % and fluocinolone acetonide 0.025 % otic solution (CIPRO+FLUO), ciprofloxacin 0.3 % otic solution alone (CIPRO), and fluocinolone acetonide 0.025 % otic solution alone (FLUO) administered into the middle ears of pediatric patients with Acute Otitis Media with Tympanostomy Tubes (AOMT). MATERIALS AND METHODS: We performed a PK analysis of patients who participated in two multicenter, randomized, double-blind AOMT clinical trials (SALVAT studies CIFLOTIII/10IA02 and CIFLOTIII/10IA04). Each patient received 0.25 mL of CIPRO+FLUO, CIPRO, or FLUO twice a day instilled into the ear canal(s) for 7 days to treat AOMT. Blood samples of patients with unilateral AOMT were collected before the administration of the first dose of study medication at Visit 1 (day 1) and within 1-2 h after the last dose on day 7. Blood samples were analyzed to detect ciprofloxacin and fluocinolone acetonide concentrations using two validated liquid chromatography-tandem mass spectrometry (LC-MS-MS) methods, with the lower limit of quantification for ciprofloxacin and fluocinolone acetonide in plasma samples being 1 ng/mL. Thirty randomly selected patients between 10 months and 10 years of age (mean age, 4.4 years) were included in the study. Although all available samples were analyzed, only PK data of the 22 patients with both samples and unilateral disease were considered for study purposes. RESULTS: No detectable concentrations of ciprofloxacin or fluocinolone acetonide in plasma were observed (<1 ng/mL). CONCLUSIONS: These results demonstrated negligible systemic exposure to ciprofloxacin and fluocinolone acetonide following topical otic administration in pediatric patients with AOMT.

Efficacy and Safety of Ciprofloxacin Plus Fluocinolone Acetonide Among Patients With Acute Otitis Externa: A Randomized Clinical Trial.

Importance: Ciprofloxacin, 0.3%, plus fluocinolone acetonide, 0.025%, otic solution seems to be efficacious and safe in treating acute otitis externa (AOE) compared with ciprofloxacin, 0.3%, or fluocinolone acetonide, 0.025%, otic solution alone. Objective: To evaluate the superiority of ciprofloxacin, 0.3%, plus fluocinolone acetonide, 0.025%, otic solution compared with ciprofloxacin, 0.3%, or fluocinolone acetonide, 0.025%, otic solution alone in treating AOE. Design, Setting, and Participants: A phase 3 randomized, double-blind, active-controlled clinical trial was conducted between August 1, 2017, and September 14, 2018, at 36 centers in the US. The study population comprised 493 patients aged 6 months or older with AOE of less than 21 days' duration with otorrhea, moderate or severe otalgia, and edema, as well as a Brighton grading of II or III (tympanic membrane obscure but without systemic illness). Statistical analysis was performed from November 14, 2018, to February 14, 2019. Interventions: Participants were randomly assigned to receive ciprofloxacin plus fluocinolone, ciprofloxacin, or fluocinolone twice daily for 7 days and were evaluated on day 1 (visit 1; baseline), days 3 to 4 (visit 2; conducted via telephone), days 8 to 10 (visit 3; end of treatment), and days 15 to 17 (visit 4; test of cure). Main Outcomes and Measures: The primary outcome was therapeutic cure (clinical and microbiological) at the end of the treatment period. The principal secondary end point was the time to end of ear pain. Efficacy analyses were conducted in the microbiological intent-to-treat population, clinical intent-to-treat population, and microbiological intent-to-treat population with Pseudomonas aeruginosa and Staphylococcus aureus. Results: A total of 493 patients (254 female patients [51.5%]; mean [SD] age, 38.2 [23.1] years) were randomized (197 to receive ciprofloxacin plus fluocinolone, 196 to receive ciprofloxacin, and 100 to receive fluocinolone). Therapeutic cure in the modified intent-to-treat population with ciprofloxacin plus fluocinolone (63 of 103 [61.2%]) was statistically comparable to that of ciprofloxacin (49 of 91 [53.8%]; difference in response rate, 7.3%; 95% CI, -6.6% to 21.2%; P = .30) and fluocinolone (20 of 45 [44.4%]; difference in response rate, 16.7%; 95% CI, -0.6% to 34.0%; P = .06) at visit 3 and significantly superior to ciprofloxacin at visit 4 (90 of 103 [87.4%] vs 69 of 91 [75.8%]; difference in response rate, 11.6%; 95% CI, 0.7%-22.4%; P = .04). A statistically faster resolution of otalgia was achieved among patients treated with ciprofloxacin plus fluocinolone (median, 5.0 days [range, 4.2-6.3 days]) vs ciprofloxacin (median, 5.9 days [range, 4.3-7.3 days]; 95% CI, 4.3-7.3 days; P = .002) or fluocinolone (median, 7.7 days [range, 6.7-9.0 days]; 95% CI, 6.7-9.0 days; P < .001). Ciprofloxacin plus fluocinolone demonstrated statistical superiority in sustained microbiological response vs ciprofloxacin (94 of 103 [91.3%] vs 74 of 91 [81.3%]; difference in response rate, 9.9%; 95% CI, 0.3%-19.6%; P = .04) and fluocinolone (34 of 45 [75.6%]; difference in response rate, 15.7%; 95% CI, 2.0%-29.4%; P = .01) and in the microbiological outcome vs fluocinolone by visit 3 (99 of 103 [96.1%] vs 37 of 45 [82.2%]; difference in response rate, 13.9%; 95% CI, 2.1%-25.7%; P = .01) and ciprofloxacin by visit 4 (97 of 103 [94.2%] vs 77 of 91 [84.6%]; difference in response rate, 9.6%; 95% CI, 0.9%-18.2%; P = .02). Fifteen adverse events related to study medications were registered, all of which were mild or moderate. Conclusions and Relevance: Ciprofloxacin, 0.3%, plus fluocinolone acetonide, 0.025%, otic solution was efficacious and safe in treating AOE but did not demonstrate superiority vs ciprofloxacin, 0.3%, or fluocinolone acetonide, 0.025%, otic solutions alone in the main study end point of therapeutic cure. Trial Registration: ClinicalTrials.gov Identifier: NCT03196973.

Simple and Efficient Synthesis of Functionalized Cyclic Carbonate Monomers Using Carbon Dioxide.

Aliphatic polycarbonates represent an important class of materials with diverse applications ranging from battery electrolytes, polyurethane intermediates, and materials for biomedical applications. These materials can be produced via the ring-opening polymerization (ROP) of six- to eight-membered cyclic carbonates derived from precursor 1,3- and 1,5-diols. These diols can contain a range of functional groups depending on the desired thermal, mechanical, and solution properties. Generally, the ring closure to form the cyclic carbonate requires the use of undesirable and hazardous reagents. Advances in synthetic methodologies and catalysis have enabled the use of carbon dioxide (CO2) to perform these transformations with a high conversion of diol to cyclic carbonate, yet modest isolated yields due to oligomerization side reactions. In this Letter, we evaluate a series of bases in the presence of p-toluenesulfonyl chloride and the appropriate diol to better understand their effect on the yield and presence of oligomer byproducts during cyclic carbonate formation from CO2. From this study, N,N-tetramethylethylenediamine (TMEDA) was identified as an optimal base, facilitating the preparation of a diverse array of both six- and eight-membered carbonates from CO2 within 10 to 15 min. The robust conditions for both, the preparation of the diol precursor, and the TMEDA-mediated carbonate synthesis enabled readily telescoping the two-step reaction sequence, greatly simplifying the process of monomer preparation.

A Cation-Dependent Dual Activation Motif for Anionic Ring-Opening Polymerization of Cyclic Esters.

A new organocatalyst for the ring-opening polymerization of lactones has been identified. Under the tested conditions, the anions of 2,2'-bisindole promote fast, living polymerizations (as short as 10 ms) which are selective for chain elongation over transesterification (D ≤ 1.1). While structurally related to (thio)urea anion catalysts, anions of 2,2'-bisindole activate the monomer via the counterion rather than through hydrogen bonding. This new activation motif enables modulation of the polymerization rate by 2 orders of magnitude by changing the counterion.

Safety and immunogenicity of an investigational quadrivalent meningococcal tetanus toxoid conjugate vaccine (MenACYW-TT) co-administered with routine pediatric vaccines in infants and toddlers: A Phase II study.

BACKGROUND: The MenACYW-TT conjugate vaccine is approved for prevention of invasive meningococcal disease (IMD) as a single dose in individuals ≥2 years of age in the United States and ≥12 months in EU and some other countries. This Phase II study evaluated the safety and immunogenicity of this vaccine and of concomitant pediatric vaccines in infants/toddlers (6 weeks-15 months of age). METHODS: Five schedules of the MenACYW-TT conjugate vaccine were evaluated in the United States: 2, 4, 6, and 12 months; 2, 4, 6, and 15 months; 2, 4, and 12 months; 6 and 12 months; and 12 months alone. Routine pediatric vaccines (DTaP-IPV/Hib, PCV7/PCV13, MMR, and varicella) were administered per approved schedules. Proportions of participants with serum bactericidal antibodyassay with human complement (hSBA) titers ≥1:4 and ≥1:8, SBA with baby rabbit complement (rSBA) titers ≥1:8 and ≥1:128, and immune responses against concomitant vaccines were determined. RESULTS: Tenderness and irritability were the most frequent solicited injection site and systemic reactions. Similar proportions of participants achieved an hSBA titer ≥1:8 for all four serogroups regardless of whether 2 or 3 doses were administered in the first year of life. Following a second-year dose, 91-100% of participants achieved the threshold for all 4 serogroups in all schedules regardless of the number of doses in the first year of life. Similar responses were seen with rSBA. Immunogenicity and safety profile of concomitant vaccines was similar whether the MenACYW-TT conjugate vaccine was administered or not. CONCLUSION: MenACYW-TT conjugate vaccine administered with pediatric vaccines is safe and immunogenic regardless of the schedule and does not affect the immunogenicity or safety of the concomitant vaccines. CLINICAL TRIAL REGISTRY: NCT01049035.

Effects of Hydrophobicity on Antimicrobial Activity, Selectivity, and Functional Mechanism of Guanidinium-Functionalized Polymers.

In this study, a series of guanidinium-functionalized polycarbonate random co-polymers is prepared from organocatalytic ring-opening polymerization to investigate the effect of the hydrophobic side chain (ethyl, propyl, isopropyl, benzyl, and hexyl) on their antimicrobial activity and selectivity. Although the polymers exhibit similar minimum inhibitory concentrations, the more hydrophobic polymers exhibit a faster rate of bacteria elimination. At higher percentage content (20 mol%), polymers with more hydrophobic side chains suffer from poor selectivity due to their high hemolytic activity. The highly hydrophobic co-polymer, containing the hydrophobic hexyl-functionalized cyclic carbonate, kills bacteria via a membrane-disruptive mechanism. Micelle formation leads to a lower extent of membrane disruption. This study unravels the effects of hydrophobic side chains on the activities of the polymers and their killing mechanism, providing insights into the design of new antimicrobial polymers.

Infant Formula with Added Bovine Milk Fat Globule Membrane and Modified Iron Supports Growth and Normal Iron Status at One Year of Age: A Randomized Controlled Trial.

Inclusion of bovine-derived milk fat globule membrane (bMFGM) or bMFGM components in infant formulas (IFs) may support healthy brain development. This double-blind, prospective trial evaluated growth, tolerance, and iron status in infants receiving added bMFGM and modified protein, iron, and arachidonic acid (ARA) concentrations in IF. Healthy term infants were randomized to: control (marketed, routine cow's milk-based IF/100 kcal: 2.1 g protein, 1.8 mg iron, 34 mg ARA) or INV-MFGM (investigational cow's milk-based IF/100 kcal: 1.9 g protein, 1.2 mg iron, 25 mg ARA and whey protein-lipid concentrate, 5 g/L (source of bMFGM)). Anthropometrics, stool characteristics, fussiness, and gassiness through day 365 and blood markers of iron status at day 365 were evaluated. The primary outcome was rate of weight gain from 14-120 days of age. Of 373 infants enrolled (control: 191, INV-MFGM: 182), 275 completed the study (control: 141; INV-MFGM: 134). No group differences in growth rate (g/day) from day 14-120 or study discontinuation were detected. Few group differences in growth or parent-reported fussiness, gassiness, or stool characteristics were detected. No group differences were detected in hemoglobin, hematocrit, or incidence of anemia. In healthy term infants, bMFGM and modified protein, iron, and ARA concentrations in a cow's milk-based IF were well-tolerated, associated with adequate growth throughout the first year of life, and supported normal iron status at one year of age.

Elucidating the anticancer activities of guanidinium-functionalized amphiphilic random copolymers by varying the structure and composition in the hydrophobic monomer.

Rationale: Use of traditional anticancer chemotherapeutics has been hindered by the multifactorial nature of multi-drug resistance (MDR) development and metastasis. Recently, cationic polycarbonates were reported as novel unconventional anticancer agents that mitigated MDR and inhibited metastasis. The aim of this study is to explore structure-anticancer activity relationship. Specifically, a series of cationic guanidinium-based random copolymers of varying hydrophobicity was synthesized with a narrow polydispersity (Ð = 1.12-1.27) via organocatalytic ring-opening polymerization (OROP) of functional cyclic carbonate monomers, and evaluated for anticancer activity, killing kinetics, degradability and functional mechanism. Methods: Linear, branched and aromatic hydrophobic side chain units, such as ethyl, benzyl, butyl, isobutyl and hexyl moieties were explored as comonomer units for modulating anticancer activity. As hydrophobicity/hydrophilicity balance of the polymers determines their anticancer efficacy, the feed ratio between the two monomers was varied to tune their hydrophobicity. Results: Notably, incorporating the hexyl moiety greatly enhanced anticancer efficiency and killing kinetics on cancer cells. Degradation studies showed that the polymers degraded completely within 4-6 days. Flow cytometry and lactate dehydrogenase (LDH) release analyses demonstrated that anticancer mechanism of the copolymers containing a hydrophobic co-monomer was concentration dependent, apoptosis at IC50, and both apoptosis and necrosis at 2 × IC50. In contrast, the homopolymer without a hydrophobic comonomer killed cancer cells predominantly via apoptotic mechanism. Conclusion: The hydrophobicity of the polymers played an important role in anticancer efficacy, killing kinetics and anticancer mechanism. This study provides valuable insights into designing novel anticancer agents utilizing polymers.

Accelerated antimicrobial discovery via deep generative models and molecular dynamics simulations.

The de novo design of antimicrobial therapeutics involves the exploration of a vast chemical repertoire to find compounds with broad-spectrum potency and low toxicity. Here, we report an efficient computational method for the generation of antimicrobials with desired attributes. The method leverages guidance from classifiers trained on an informative latent space of molecules modelled using a deep generative autoencoder, and screens the generated molecules using deep-learning classifiers as well as physicochemical features derived from high-throughput molecular dynamics simulations. Within 48 days, we identified, synthesized and experimentally tested 20 candidate antimicrobial peptides, of which two displayed high potency against diverse Gram-positive and Gram-negative pathogens (including multidrug-resistant Klebsiella pneumoniae) and a low propensity to induce drug resistance in Escherichia coli. Both peptides have low toxicity, as validated in vitro and in mice. We also show using live-cell confocal imaging that the bactericidal mode of action of the peptides involves the formation of membrane pores. The combination of deep learning and molecular dynamics may accelerate the discovery of potent and selective broad-spectrum antimicrobials.

Cationic polymer synergizing with chemotherapeutics and re-purposing antibiotics against cancer cells.

Chemotherapy is one of the most effective treatments for cancer. However, toxicity and the development of drug resistance have become the major hurdles to the commonly used chemotherapeutics such as doxorubicin and paclitaxel. Antibiotics have also been used as anti-cancer drugs due to their anti-proliferative and cytotoxic effects. However, these anti-tumor antibiotics like ciprofloxacin face the similar resistance and toxicity issues. In this study, we used a quaternary ammonium-functionalized cationic polycarbonate to synergize with the existing chemotherapeutics and re-purpose antibiotics to address the resistance and toxicity issues. When used in combination with the drugs, the cationic polymer induced 2-3 fold more damage in the cancer cell membrane within 2 hours, thus enhancing the uptake of chemotherapeutics up to 2.5 fold more into the breast, liver and even chemotherapeutics-resistant cancer cells. On the other hand, the chemotherapeutics increased the cellular uptake of polymer. The combined effects resulted in 3-10 fold reduction in IC50 of chemotherapy drugs and yielded therapeutic synergy at a clinically-relevant concentration range of drugs when treating multiple types of cancer cells, while the use of guanidinium-functionalized polymer capable of membrane translocation did not lead to a synergistic effect. Thus, the quaternary ammonium-functionalized cationic polymer can increase the therapeutic efficacies of existing drugs, mitigating toxicities by lowering required dosage and circumventing drug resistance via its membrane disruption mechanism. The findings of this study provide insights into designing future anticancer therapy.

Selective Chemical Upcycling of Mixed Plastics Guided by a Thermally Stable Organocatalyst.

Chemical recycling of plastic waste represents a greener alternative to landfill and incineration, and potentially offers a solution to the environmental consequences of increased plastic waste. Most plastics that are widely used today are designed for durability, hence currently available depolymerisation methods typically require harsh conditions and when applied to blended and mixed plastic feeds generate a mixture of products. Herein, we demonstrate that the energetic differences for the glycolysis of BPA-PC and PET in the presence of a protic ionic salt TBD:MSA catalyst enables the selective and sequential depolymerisation of these two commonly employed polymers. Employing the same procedure, functionalised cyclic carbonates can be obtained from both mixed plastic wastes and industrial polymer blend. This methodology demonstrates that the concept of catalytic depolymerisation offers great potential for selective polymer recycling and also presents plastic waste as a "greener" alternative feedstock for the synthesis of high added value molecules.

Carboxylic acid-functionalized polycarbonates as bone cement additives for enhanced and sustained release of antibiotics.

Despite the good clinical outcomes of total joint replacements, prosthetic joint infections still remain a significant cause of implant failure. Primary prophylaxis is key to stemming this burgeoning problem and its associated complications. In this study, a series of bone cement formulations with enhanced antibacterial performance have been developed through the addition of carboxylic acid-functionalized polycarbonate block copolymers to commercially available bone cement. Block copolymer design features were specifically tailored to modulate the acidity for adsorption of antibiotic and phase separation of the copolymers within the polymerizing/hardening of the cement during application. The best performing polymers demonstrated sustained antimicrobial release for more than 259 days and 147 days against S. aureus and P. aeruginosa, respectively, compared to 70 days of activity seen with commercially available gentamicin-containing cement control; whilst in vitro gentamicin release was increased by 8-fold. Total porosity was also increased 3-fold from 4.3% to 12.5%, whilst maintaining the mechanical integrity, working characteristics and osteoblastic biocompatibility of bone cement. Taken together, carboxylic acid-functionalized polycarbonates represent a promising class of bone cement additives that can be used to enhance the antibacterial performance of the bone cement whilst maintaining mechanical strength and cellular biocompatibility.

Biodegradable Cationic Polycarbonates as Vaccine Adjuvants.

In this study, biodegradable cationic polycarbonate and polylactide block copolymers were synthesized and successfully used as novel vaccine adjuvants to provide enhanced anticancer immunity. The polymers formed nanoparticles with the model vaccine, ovalbumin (OVA), and the immunostimulant toll-like receptor 3 agonist poly(I:C) (a synthetic analog of the double-stranded RNA). Higher uptake of poly(I:C) by the bone marrow-derived dendritic cells and macrophages and OVA by dendritic cells was observed when delivered using the polymer adjuvant. In vivo experiments showed that these nanoparticles remained longer in the subcutaneous injection site as compared to OVA alone and led to higher production of anti-OVA specific antibodies with prolonged immunostimulation. When OVA was combined with poly(I:C) that was either co-entrapped in the same particles or as separate particles, a comparable level of anti-OVA IgG1 antibodies and interleukin-6 (IL-6) was produced in mouse blood plasma, and a similar level of cytotoxic T lymphocyte (CTL) response in mice was stimulated as compared to OVA/Alum particles. Furthermore, tumor rejection in the mice that were vaccinated for 9 months with the formulations containing the polymer adjuvant was stronger than the other treatment groups without the polymer. Notably, the cationic polycarbonates were not associated with any adverse in vivo effects. Thus, these biodegradable polymers may be promising substitutes for aluminum-based adjuvants in vaccine formulations.