Heterochiral ß-Peptide Polymers Combating Multidrug-Resistant Cancers Effectively without Inducing Drug Resistance.

Multidrug resistance to chemotherapeutic drugs is one of the major causes for the failure of cancer treatment. Therefore, there is an urgent need to develop anticancer agents that can combat multidrug-resistant cancers effectively and mitigate drug resistance. Here, we report a rational design of anticancer heterochiral ß-peptide polymers as synthetic mimics of host defense peptides to combat multidrug-resistant cancers. The optimal polymer shows potent and broad-spectrum anticancer activities against multidrug-resistant cancer cells and is insusceptible to anticancer drug resistance owing to its membrane-damaging mechanism. The in vivo study indicates that the optimal polymer efficiently inhibits the growth and distant transfer of solid tumors and the metastasis and seeding of circulating tumor cells. Moreover, the polymer shows excellent biocompatibility during anticancer treatment on animals. In addition, the ß-peptide polymers address those prominent shortcomings of anticancer peptides and have superior stability against proteolysis, easy synthesis in large scale, and low cost. Collectively, the structural diversity and superior anticancer performance of ß-peptide polymers imply an effective strategy in designing and finding anticancer agents to combat multidrug-resistant cancers effectively while mitigating drug resistance.

Secondary Amine Pendant ß-Peptide Polymers Displaying Potent Antibacterial Activity and Promising Therapeutic Potential in Treating MRSA-Induced Wound Infections and Keratitis.

Interest in developing antibacterial polymers as synthetic mimics of host defense peptides (HPDs) has accelerated in recent years to combat antibiotic-resistant bacterial infections. Positively charged moieties are critical in defining the antibacterial activity and eukaryotic toxicity of HDP mimics. Most examples have utilized primary amines or guanidines as the source of positively charged moieties, inspired by the lysine and arginine residues in HDPs. Here, we explore the impact of amine group variation (primary, secondary, or tertiary amine) on the antibacterial performance of HDP-mimicking ß-peptide polymers. Our studies show that a secondary ammonium is superior to either a primary ammonium or a tertiary ammonium as the cationic moiety in antibacterial ß-peptide polymers. The optimal polymer, a homopolymer bearing secondary amino groups, displays potent antibacterial activity and the highest selectivity (low hemolysis and cytotoxicity). The optimal polymer displays potent activity against antibiotic-resistant bacteria and high therapeutic efficacy in treating MRSA-induced wound infections and keratitis as well as low acute dermal toxicity and low corneal epithelial cytotoxicity. This work suggests that secondary amines may be broadly useful in the design of antibacterial polymers.

Enhanced Antitumor Efficacy of Curcumin-Loaded PLGA Nanoparticles Coated with Unique Fungal Hydrophobin.

Modifications to the surface chemistry, charge, and hydrophilicity/hydrophobicity of nanoparticles are applicable approaches to the alterations of the in vivo fate of intravenously administered nano-sized drug carriers. The objective of this study is to investigate the in vitro and in vivo antitumor efficacies of curcumin PLGA nanoparticles in relation to their surface structural modification via self-assembling coating with unique fungal hydrophobin. The hydophobin-coated curcumin PLGA nanoparticles (HPB PLGA NPs) were obtained by simply soaking curcumin-loaded PLGA nanoparticles (PLGA NPs) in aqueous fungal hydrophobin solution. The in vitro drug release behavior of the HPB PLGA NPS was also tested. The cytotoxicity and cellular uptake of these nanoparticles were determined in HepG2, A549, and Hela cell lines using MTT assay method and CLSM observation. The in vivo antitumor activity was evaluated in Hela tumor xenografted mice model. Compared with the PLGA NPs, the size and zeta potential of the nanoparticles were changed after hydrophobin coating, whereas similar in vitro release pattern was observed. The pharmacodynamics study showed prolonged blood retention of both nano-formulations than that of free curcumin, but no significant difference between the hydrophobin coated and uncoated nanoparticles. It was found that HPB PLGA NPs had increased cytotoxicities, higher cellular uptake, and improved antitumor efficacy. Surface modification of nanoparticles via self-assembling of hydrophobin is a convenient and promising method of changing particle surface physiochemical properties and antitumor performances. Further investigations, especially on tissue distribution, were needed to assess the potential application of the hydrophobin self-assembling coating in nano-drug delivery carriers.

Biodegradable peptide polymers as alternatives to antibiotics used in aquaculture.

The pressure of antimicrobial resistance has forced many countries to reduce or even prohibit the use of antibiotics in feed. Therefore, it is an urgent need to develop alternatives to antibiotics to control infectious diseases in feed and aquaculture. To address this long-lasting challenge, we prepared peptide polymers that display potent and broad-spectrum activity against common pathogenic bacteria in aquaculture, low hemolysis and low cytotoxicity, and do not induce bacteria to develop resistance or cross-resistance to antibiotics. The optimal peptide polymer demonstrates strong in vivo therapeutic potential in an adult zebrafish infection model. Moreover, the optimal peptide polymer is biodegradable by enzymes into single amino acids and dipeptides to totally lose its antibacterial activity and, therefore, will not cause antimicrobial selective pressure. Our study suggests that peptide polymers are promising alternatives to antibiotics in aquaculture and open new avenues to address the global challenge of antimicrobial resistance.

An Effective Strategy to Develop Potent and Selective Antifungal Agents from Cell Penetrating Peptides in Tackling Drug-Resistant Invasive Fungal Infections.

The high mortality rate of invasive fungal infections and quick emergence of drug-resistant fungal pathogens urgently call for potent antifungal agents. Inspired by the cell penetrating peptide (CPP) octaarginine (R8), we elongated to 28 residues poly(d,l-homoarginine) to obtain potent toxicity against both fungi and mammalian cells. Further incorporation of glutamic acid residues shields positive charge density and introduces partial zwitterions in the obtained optimal peptide polymer that displays potent antifungal activity against drug-resistant fungi superior to antifungal drugs, excellent stability upon heating and UV exposure, negligible in vitro and in vivo toxicity, and strong therapeutic effects in treating invasive fungal infections. Moreover, the peptide polymer is insusceptible to antifungal resistance owing to the unique CPP-related antifungal mechanism of fungal membrane penetration followed by disruption of organelles within fungal cells. All these merits imply the effectiveness of our strategy to develop promising antifungal agents.

Microbial Metabolite Inspired ß-Peptide Polymers Displaying Potent and Selective Antifungal Activity.

Potent and selective antifungal agents are urgently needed due to the quick increase of serious invasive fungal infections and the limited antifungal drugs available. Microbial metabolites have been a rich source of antimicrobial agents and have inspired the authors to design and obtain potent and selective antifungal agents, poly(DL-diaminopropionic acid) (PDAP) from the ring-opening polymerization of ß-amino acid N-thiocarboxyanhydrides, by mimicking ε-poly-lysine. PDAP kills fungal cells by penetrating the fungal cytoplasm, generating reactive oxygen, and inducing fungal apoptosis. The optimal PDAP displays potent antifungal activity with minimum inhibitory concentration as low as 0.4 µg mL-1 against Candida albicans, negligible hemolysis and cytotoxicity, and no susceptibility to antifungal resistance. In addition, PDAP effectively inhibits the formation of fungal biofilms and eradicates the mature biofilms. In vivo studies show that PDAP is safe and effective in treating fungal keratitis, which suggests PDAPs as promising new antifungal agents.

Recent Advances in Microfluidic Platforms for Programming Cell-Based Living Materials.

Cell-based living materials, including single cells, cell-laden fibers, cell sheets, organoids, and organs, have attracted intensive interests owing to their widespread applications in cancer therapy, regenerative medicine, drug development, and so on. Significant progress in materials, microfabrication, and cell biology have promoted the development of numerous promising microfluidic platforms for programming these cell-based living materials with a high-throughput, scalable, and efficient manner. In this review, the recent progress of novel microfluidic platforms for programming cell-based living materials is presented. First, the unique features, categories, and materials and related fabrication methods of microfluidic platforms are briefly introduced. From the viewpoint of the design principles of the microfluidic platforms, the recent significant advances of programming single cells, cell-laden fibers, cell sheets, organoids, and organs in turns are then highlighted. Last, by providing personal perspectives on challenges and future trends, this review aims to motivate researchers from the fields of materials and engineering to work together with biologists and physicians to promote the development of cell-based living materials for human healthcare-related applications.

Addressing MRSA infection and antibacterial resistance with peptoid polymers.

Methicillin-Resistant Staphylococcus aureus (MRSA) induced infection calls for antibacterial agents that are not prone to antimicrobial resistance. We prepare protease-resistant peptoid polymers with variable C-terminal functional groups using a ring-opening polymerization of N-substituted N-carboxyanhydrides (NNCA), which can provide peptoid polymers easily from the one-pot synthesis. We study the optimal polymer that displays effective activity against MRSA planktonic and persister cells, effective eradication of highly antibiotic-resistant MRSA biofilms, and potent anti-infectious performance in vivo using the wound infection model, the mouse keratitis model, and the mouse peritonitis model. Peptoid polymers show insusceptibility to antimicrobial resistance, which is a prominent merit of these antimicrobial agents. The low cost, convenient synthesis and structure diversity of peptoid polymers, the superior antimicrobial performance and therapeutic potential in treating MRSA infection altogether imply great potential of peptoid polymers as promising antibacterial agents in treating MRSA infection and alleviating antibiotic resistance.

Efficient synthesis of amino acid polymers for protein stabilization.

Proteins are fragile such that even freezing, drying and dehydration may induce their denaturation, aggregation, and activity loss. To protect proteins from these kinds of damage, we prepared two types of amino acid polymers, poly-(l-glutamate)-r-poly-(l-lysine) (PLG-r-PLL) and poly-l-glutamate (PLG), from the efficient ring-opening polymerization of α-amino acid N-carboxyanhydride (NCA) using lithium hexamethyldisilazide (LiHMDS) as the initiator. ß-galactosidase (ß-Gal) was used in this study to examine the protein protecting effect of the synthesized amino acid polymers during lyophilization. The results indicate that both PLG-r-PLL and PLG exert significant protection on ß-Gal during lyophilization and improve the activity of the resulting protein from 40%, without using a protecting agent during lyophilization, to 80% of the original protein activity. Nevertheless, PLG generally performs better than PLG-r-PLL independent of the chain length. Our studies also show that PLG and PLG-r-PLL with a high content of PLG subunits display no observable cytotoxicity and hemolytic effect. Furthermore, dynamic light scattering (DLS) and transmission electron microscopy (TEM) characterization indicate that PLG protects ß-Gal upon lyophilization by preventing the aggregation of ß-Gal. Our studies demonstrate that amino acid polymers, such as PLG, can exert potent activity for protein stabilization. The easy operation of LiHMDS-initiated and efficient NCA polymerization implies the great potential of this strategy to prepare amino acid polymers quickly for the screening of protein stabilization and mechanism study.

Practical Preparation of Infection-Resistant Biomedical Surfaces from Antimicrobial ß-Peptide Polymers.

Tackling microbial infection associated with biomaterial surfaces has been an urgent need. Synthetic ß-peptide polymers can mimic host defense peptides and have potent antimicrobial activities without driving the bacteria to develop antimicrobial resistance. Herein, we demonstrate a plasma surface activation-based practical ß-peptide polymer modification to prepare antimicrobial surfaces for biomedical materials such as thermoplastic polyurethane (TPU), polytetrafluoroethylene, polyvinyl pyrrolidone, polyvinyl chloride, and polydimethylsiloxane. The ß-peptide polymer-modified surfaces demonstrated effective killing on drug-resistant Gram-positive and Gram-negative bacteria. The antibacterial function retained completely even after the ß-peptide polymer-modified surfaces were stored at ambient temperature for at least 2 months. Moreover, the optimum ß-peptide polymer (50:50 DM-Hex)-modified surfaces displayed no hemolysis and cytotoxicity. In vivo study using methicillin-resistant Staphylococcus aureus (MRSA)-pre-incubated TPU-50:50 DM-Hex surfaces for subcutaneous implantation revealed a 3.4-log reduction of MRSA cells after the implantation for 11 days at the surrounding tissue of implanted TPU sheet and significant suppression of infection, compared to bare TPU control. These results imply promising and practical applications of ß-peptide polymer tethering to prepare infection-resistant surfaces for biomedical materials and devices.

[The distribution of azidothymidine palmitate galactosylated liposomes in mice].

Hepatocytes act as a reservoir for the human immunodeficiency viruses (HIV) and are responsible for its continual dissemination in the peripheral circulation. For this reason, galactosylated liposomes (GalLs) containing home-made [(2-lactoylamido) ethylamino] formic acid cholesterol ester (CH-ED-LA ) as a homing device were prepared to study the biodistribution of the liposomal azidothymidine palmitate (AZTP) in mice. Four liposomes of the present study, soybean phosphatidylcholine (SPC)/cholesterol(CH)/CH-ED-LA (80 : 10: 10, 10% GalLs), SPC/CH/CH-ED-LA (80 : 15:5, 5% GalLs), SPC/CH/CH-ED-LA (80 : 17 : 3, 3% GallLs) and SPC/CH (80 : 20, CL) incorporated AZTP were prepared by ethanol-injection method followed by ultrasonic-dispersion and characterized by entrapped efficiency which was more than 95% and their mean diameter was less than 100 nm, respectively. The effects of the addition upon the liposomal membrane potential and AZTP content were also unseen. The distributions of AZT in various organs were determinated by reversed phase HPLC after intravenous administration via tail vein in mice, at a dose of 15.85 mg x kg(-1) AZT solution and 30 mg x kg(-1) AZTP (at equimolar doses) in CL or GalLs, respectively. Compared to AZT control solution, the half-life of AZT in each group of AZTP liposomes increased significantly (P < 0.05). In addition, the concentration-averaged overall drug targeting efficiency (r(e)) of the liver presented by AZTP CL and GalLs containing 3% , 5% , 10% (mol/mol) CH-ED-LA increased 1.32 and 1.48, 2.13, 1.50 times as that of AZT solution, respectively. These results indicate that liposomes containing such novel galactosylated lipid, CH-ED-LA, had remarkably improved the targetability of AZTP to liver, and are anticipated to be a potential candidate for liver targeting delivery carriers.

[Changes in expressions of sRNA SpR19 and its potential target GroEL in Streptococcus mutans strains with different cariogenicity cultured under different pH conditions].

OBJECTIVE: To investigate the changes in the expression level of sRNA SpR19 and its potential target protein GroEL in clinical isolates of Streptococcus mutans with different cariogenicity exposed to different pH conditions and explore the possibility of using these molecules as biomarkers for assessing the cariogenicity of the bacteria. METHODS: The total RNAs were extracted from the clinical isolates of Streptococcus mutans with high (strain 17) and low cariogenicity (strain 5) for high-throughput sequencing for profiling of the differentially expressed sRNAs. The candidate sRNA, SpR19, was selected for further study on the basis of bioinformatics analysis considering the role of its potential target in the cariogenic process. The differential expression levels of SpR19 in the strains exposed to both pH5.5 and pH7 culture conditions were verified by quantitative real-time PCR. The expression of the potential target of SpR19, GroEL, was also investigated at both the protein and mRNA level using Western blotting and quantitative real-time PCR. RESULTS: Bioinformatic analysis suggested multiple potential target sites of SpR19 both in GroEL mRNA and in the upstream and downstream inter-genic regions. Under different pH conditions, the highly cariogenic strain 17 expressed consistently low levels of SpR19 as compared with the strain 5 with a low cariogenicity; GroEL showed a reverse expression pattern in the 2 strains. An inverse correlation was found between the expressions of SpR19 and GroEL. CONCLUSION: The highly cariogenic strain 17 expressed low levels of SpR19 and high levels of GroEL in both acidic and neutral culture conditions. SpR19 may negatively regulate the cariogenicity of Streptococcus mutants by targeting at GroEL.

Synthesis of a novel galactosylated lipid and its application to the hepatocyte-selective targeting of liposomal doxorubicin.

This paper described the synthesis of a novel galactosylated lipid with mono-galactoside moiety, (5-Cholesten-3beta-yl) 4-oxo-4-[2-(lactobionyl amido) ethylamido] butanoate (CHS-ED-LA), and the targetability of doxorubicin (DOX), a model drug, in liposomes containing 10% mol/mol CHS-ED-LA (galactosylated liposomes, GalL) to the liver was studied. The weighted-average overall drug targeting efficiency (Te(*)) was used to evaluate the liver targetability of GalL DOX. The results showed that GalL DOX gave a relatively high (Te(*))(liver) value of 64.6%, while DOX in conventional liposome (CL DOX) only gave a (Te(*))(liver) value of 21.8%. In the liver, the GalL DOX was mainly taken up by parenchymal cells (88% of the total hepatic uptake). Moreover, preinjection of asialofetuin significantly inhibited the liver uptake of GalL DOX (from 70 to 12% of the total injected dose). It was suggested that liposomes containing such novel galactosylated lipid, CHS-ED-LA, had a great potential as drug delivery carriers for hepatocyte-selective targeting.

Integrin-specific hydrogels as adaptable tumor organoids for malignant B and T cells.

Non-Hodgkin lymphomas are a heterogeneous group of lymphoproliferative disorders of B and T cell origin that are treated with chemotherapy drugs with variable success rate that has virtually not changed over decades. Although new classes of chemotherapy-free epigenetic and metabolic drugs have emerged, durable responses to these conventional and new therapies are achieved in a fraction of cancer patients, with many individuals experiencing resistance to the drugs. The paucity in our understanding of what regulates the drug resistance phenotype and establishing a predictive indicator is, in great part, due to the lack of adequate ex vivo lymphoma models to accurately study the effect of microenvironmental cues in which malignant B and T cell lymphoma cells arise and reside. Unlike many other tumors, lymphomas have been neglected from biomaterials-based microenvironment engineering standpoint. In this study, we demonstrate that B and T cell lymphomas have different pro-survival integrin signaling requirements (αvß3 and α4ß1) and the presence of supporting follicular dendritic cells are critical for enhanced proliferation in three-dimensional (3D) microenvironments. We engineered adaptable 3D tumor organoids presenting adhesive peptides with distinct integrin specificities to B and T cell lymphoma cells that resulted in enhanced proliferation, clustering, and drug resistance to the chemotherapeutics and a new class of histone deacetylase inhibitor (HDACi), Panobinostat. In Diffuse Large B cell Lymphomas, the 3D microenvironment upregulated the expression level of B cell receptor (BCR), which supported the survival of B cell lymphomas through a tyrosine kinase Syk in the upstream BCR pathway. Our integrin specific ligand functionalized 3D organoids mimic a lymphoid neoplasm-like heterogeneous microenvironment that could, in the long term, change the understanding of the initiation and progression of hematological tumors, allow primary biospecimen analysis, provide prognostic values, and importantly, allow a faster and more rational screening and translation of therapeutic regimens.