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We demonstrate selective capturing of exosomes for surface-enhanced Raman spectroscopy (SERS) analysis using a thiolated peptide ligand that is bound to the surface of silver nanoparticles via thiol-metallic bond formation. The ligand preferentially binds to α3s1 integrin over-expressed in exosomes secreted from SKOV-3 cancer cells. Several Raman peaks at 894 cm−1, 1,080 cm−1, 1,252 cm−1, 1,340 cm−1, and 1,380 cm−1 specific to SKOV-3 exosomes are detected above the background signals generated from the nanoparticle and the ligand. In comparison, α3s1 integrin negative exosomes secreted from Jurkat cells showed no detectable exosome specific SERS signal, confirming the high specificity of this ligand-based SERS detection approach. This study shows the potential of developing a target-specific SERS detection approach for characterizing exosomes from a heterogeneous mixture in body fluid for early-stage disease diagnostics.

The role of phonics instruction in early reading development has been the subject of significant conjecture. Recently, England implemented a phonics screening check to assess the phonetic decoding of 6‐year‐old students, to ensure that all students master this foundational literacy skill and attain adequate phonemic awareness in the early years of primary schooling. Students who fail this check are obliged to retake the assessment the following year. In this article, we compare the performance of students who initially pass this check (pass) and students who fail the original assessment but pass the retaken assessment (fail–pass), with students who fail both the original and retaken assessments (fail–fail). Using data from the Key Stage 1 assessment of reading and the Progress in International Reading Literacy Study (PIRLS), we examined the reading comprehension performance of these students approximately 1 and 4 years after their first phonics screening. The results suggested that fail–pass students performed substantially better than fail–fail students, even after performance on the initial phonics check was controlled for. While fail–pass students do not appear to entirely catch up with pass students in reading comprehension, their relatively better performance underscores the importance of intervening for those students who are identified as having problems with phonetic decoding to increase their likelihood of success at reading comprehension in later schooling.

Systemic chemotherapy is efficacious against triple-negative breast cancer (TNBC), but it is often associated with serious side effects. Here, we report a luteinizing hormone-releasing hormone (LHRH) receptor-targeted and tumor microenvironment-responsive nanoparticle system to selectively deliver chemotherapeutic drugs to TNBC cells. This delivery system (termed “LHRH-DCMs”) contains poly (ethylene glycol) and dendritic cholic acid as a micellar carrier, reversible intra-micellar disulfide bond as a redox-responsive crosslink, and synthetic high-affinity (D-Lys)-LHRH peptide as a targeting moiety. LHRH-DCMs exhibited high drug loading efficiency, optimal particle size, good colloidal stability, and glutathione-responsive drug release. As expected, LHRH-DCMs were more efficiently internalized into human TNBC cells through receptor-mediated endocytosis, resulting in stronger cytotoxicity against these cancer cells than nontargeted counterpart when encapsulated with paclitaxel (PTX). Furthermore, near-infrared fluorescence and magnetic resonance imaging demonstrated that LHRH-DCMs facilitated the tumor distribution and penetration of payloads in three different animal models of breast cancer, including cell line-derived xenograft (CDX), patient-derived xenograft (PDX), and transgenic mammary carcinoma. Finally, in vivo therapeutic studies showed that PTX-LHRH-DCMs outperformed both the corresponding nontargeted PTX-DCMs and the current clinical formulation (Taxol(®)) in an orthotopic TNBC model. These results provide new insights into approaches for precise drug delivery of TNBC.

The efficacy of therapeutics for brain tumors is seriously hampered by multiple barriers to drug delivery, including severe destabilizing effects in the blood circulation, the blood-brain barrier/blood-brain tumor barrier (BBB/BBTB), and limited tumor uptake. Here, a sequential targeting in crosslinking (STICK) nanodelivery strategy is presented to circumvent these important physiological barriers to improve drug delivery to brain tumors. STICK nanoparticles (STICK-NPs) can sequentially target BBB/BBTB and brain tumor cells with surface maltobionic acid (MA) and 4-carboxyphenylboronic acid (CBA), respectively, and simultaneously enhance nanoparticle stability with pH-responsive crosslinkages formed by MA and CBA in situ. STICK-NPs exhibit prolonged circulation time (17-fold higher area under curve) than the free agent, allowing increased opportunities to transpass the BBB/BBTB via glucose-transporter-mediated transcytosis by MA. The tumor acidic environment then triggers the transformation of the STICK-NPs into smaller nanoparticles and reveals a secondary CBA targeting moiety for deep tumor penetration and enhanced uptake in tumor cells. STICK-NPs significantly inhibit tumor growth and prolong the survival time with limited toxicity in mice with aggressive and chemoresistant diffuse intrinsic pontine glioma. This formulation tackles multiple physiological barriers on-demand with a simple and smart STICK design. Therefore, these features allow STICK-NPs to unleash the potential of brain tumor therapeutics to improve their treatment efficacy.

Nanolipoprotein particles (NLPs) are nanometer-scale discoidal particles that feature a phospholipid bilayer confined within an apolipoprotein “scaffold,” which are useful for solubilizing hydrophobic molecules such as drugs and membrane proteins. NLPs are synthesized either by mixing the purified apolipoprotein with phospholipids and other cofactors or by cell-free protein synthesis followed by self-assembly of the nanoparticles in the reaction mixture. Either method can be problematic regarding the production of homogeneous and monodispersed populations of NLPs, which also currently requires multiple synthesis and purification steps. Telodendrimers (TD) are branched polymers made up of a dendritic oligo-lysine core that is conjugated to linear polyethylene glycol (PEG) on one end, and the lysine “branches” are terminated with cholic acid moieties that enable the formation of nanomicelles in aqueous solution. We report herein that the addition of TD during cell-free synthesis of NLPs produces unique hybrid nanoparticles that have drastically reduced polydispersity as compared to NLPs made in the absence of TD. This finding was supported by dynamic light scattering, fluorescence correlation spectroscopy, and cryo transmission electron microscopy (Cryo-EM). These techniques demonstrate the ability of TDs to modulate both the NLP size (6–30 nm) and polydispersity. The telodendrimer NLPs (TD-NLPs) also showed 80% less aggregation as compared to NLPs alone. Furthermore, the versatility of these novel nanoparticles was shown through direct conjugation of small molecules such as fluorescent dyes directly to the TD as well as the insertion of a functional membrane protein.

Stimuli-responsive nanoparticles are gaining considerable attention in the field of drug delivery due to their useful physicochemical changes in response to specific triggers, such as pH[1], temperature[2], enzymes[3] or redox conditions[4], present in certain physiological or disease microenvironment of interest. Among these nanoparticles, stimuli-responsive cross-linked micelles (SCMs) represent a versatile nanocarrier system for tumor targeting drug delivery[2c, 4-5]. For instance, SCMs exhibit superior structural stability under physiological condition compared to the non-crosslinked counterpart. As a result, these nanocarriers are able to better retain the encapsulated drug and minimize its premature release while circulating in the blood pool[2c, 4b, 5b]. The introduction of environmentally sensitive crosslinkers makes SCMs responsive to the local environment of the tumor (e.g. tumor extra-cellular pH (6.5-7.2), endosomal/lysosomal pH (4.5–6)[5b, 6], and tumor reductive intra-cellular condition[4-5]). In these instances, the payload drug is released almost exclusively in the cancerous tissue upon accumulation via the well known enhanced permeation and retention (EPR) effect[2c, 4b, 5b].

Novel foods have been the object of intense public debate in recent years. Despite widespread efforts to communicate the outcomes of risk assessments to consumers, public confidence in risk management has been low. Social scientists have identified various reasons for this, including a disagreement between technical experts and consumers over the nature of the hazards on which risk assessments should focus. The aim of this study was to identify and compare the ways in which experts and consumers understand the benefits and risks associated with a genetically modified example crop. Two qualitative studies were conducted. In Study 1, mental models were elicited from 24 experts by means of a three-wave Delphi procedure. In Study 2, mental models were elicited from 25 consumers by means of in-depth interviews. As expected, the expert mental models were focused on the types of hazards that can realistically be addressed under current regulatory frameworks, whereas the consumers were often more concerned about issues outside the scope of current legislation. Moreover, the experts tended to define risk and benefit in terms of detailed chains of cause-effect relationships between variables for which clear definitions and measurement rules exist. The concepts the consumers used when reasoning about biological processes were very abstract, suggesting that the participants had, at most, a holistic understanding. In line with this, issues of uncertainty played a prominent role for the consumers. Novel foods have been the object of intense public debate in recent years. Despite widespread efforts to communicate the outcomes of risk assessments to consumers, public confidence in risk management has been low. Social scientists have identified various reasons for this, including a disagreement between technical experts and consumers over the nature of the hazards on which risk assessments should focus. The aim of this study was to identify and compare the ways in which experts and consumers understand the benefits and risks associated with a genetically modified example crop. Two qualitative studies were conducted. In Study 1, mental models were elicited from 24 experts by means of a three-wave Delphi procedure. In Study 2, mental models were elicited from 25 consumers by means of in-depth interviews. As expected, the expert mental models were focused on the types of hazards that can realistically be addressed under current regulatory frameworks, whereas the consumers were often more concerned about issues outside the scope of current legislation. Moreover, the experts tended to define risk and benefit in terms of detailed chains of cause-effect relationships between variables for which clear definitions and measurement rules exist. The concepts the consumers used when reasoning about biological processes were very abstract, suggesting that the participants had, at most, a holistic understanding. In line with this, issues of uncertainty played a prominent role for the consumers.

We recently reported the use of a biphasic approach to generate topologically segregated bilayer beads. In generating 'one-bead one-compound' (OBOC) combinatorial libraries, novel encoding methods have been applied to these beads such as the testing library compound and the coding tags residing on the outer layer and inner core of each bead, respectively. In this report, we further exploit these bilayer beads by preparing target bead-libraries with low concentration of random peptides on the outer layer, and full substitution of coding peptides in the bead interior. The low concentration of peptide on the bead surface enables us to greatly increase the stringency of screening so that higher affinity ligands can easily be identified. Full substitution of the inner core of the beads enables us to have enough coding peptides inside the bead for direct microsequencing with Edman chemistry. The biphasic approach of preparing bilayer beads can be carried out at any point during the library construction. Therefore, the nonsequencable or fixed structures of the peptides can be bypassed in the coding tags. As a result, peptide libraries that otherwise cannot be sequenced can now be sequenced, and peptide segments with fixed residues within the libraries can be bypassed so that the microsequencing time can be significantly shortened. Furthermore, peptides with a branch of random sequence in the middle of a fixed peptide chain can be encoded with just the random sequence in the bead interior. We have successfully applied these novel OBOC library concepts in the optimization of cell-surface ligands for a human T-cell leukemia, Jurkat, cell line.

α4β1 integrin is a therapeutic target for inflammation, autoimmune diseases, and lymphoid cancers. A series of peptidomimetic ligands based on the Nle-D-I motif have been synthesized and their binding affinities (IC50) to activated α4β1 integrin on Jurkat T-leukemia cells have been determined using a cell adhesion assay. One of the 51 ligands, 18, has been determined to have an IC50 of 0.6 nM and has a more than twofold increase of binding affinity than the initial lead compound 1. Extensive SAR studies provide important information for further ligand optimization, which has served as a foundation for studies that ultimately led to identification of a potent ligand with an IC50 of 2 pM. © 2006 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 84: 595–604, 2006 This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com

Using a “split – mix” synthesis approach, “One-Bead One-Compound” (OBOC) combinatorial libraries can be generated such that each bead displays only one chemical entity. Tens of thousands to millions of compound-beads can be screened concurrently using a variety of biochemical and cell-based screening methods. Positive beads are then physically isolated for structure determination. Peptide beads or peptoid beads consisting of a-amino acids and with a free N-terminus can be routinely sequenced by an automatic microsequencer using Edman chemistry. Libraries with N-terminally blocked peptides, peptides with unsequenceable building blocks, or small molecules require encoding. To fully exploit the OBOC combinatorial library methods, we have developed topologically segregated bilayer beads. Such bilayer beads allow us to prepare library compound on the outer layer of each bead and the coding tags in the bead interior. In addition, we can use these bilayer beads to prepare OBOC combinatorial libraries that are down-substituted on the bead surface but fully substituted in the bead interior. This configuration enables one to screen at a much higher stringency and yet have enough peptides or coding tags retained in the bead interior for structure determination.

The cytoplasmic protein p60c-src, an ubiquitous non-receptor protein tyrosine kinase (PTK) is a potential anticancer target as it is over-expressed and/or constitutively active in several cancer types. In addition, the phenotype of c-src knock-out mice is consistent with osteopetrosis, which suggests that inhibitors against this enzyme may also be therapeutic for osteoporosis. Using a known peptide substrate for c-src, MIYKYYF, as a template, we have developed a series of pseudosubstrate-based peptide inhibitors. Structure-activity relationship studies have been performed on one of these inhibitors, CIYKYYF. In a kinase assay using YIYGSFK as the substrate, CIYKYY has been demonstrated to inhibit p60c-src, with an IC50 of 0.6 microm. Further truncation has led to the determination that even the smaller peptide, CIYK, is a moderately potent inhibitor with IC50 of 15 microm. Some improvement in inhibitory potency (IC50 = 11.8 microm) has been observed with the replacement of Tyr3 in CIYK with beta-phenylalanine (beta-Phe). The tetrapeptide CI(beta-Phe)K will be used as a lead compound for future development of peptidomimetics and small molecule inhibitors that have the capacity to penetrate the plasma membrane of intact cells.