Rapid and low-cost sampling for detection of airborne SARS-CoV-2 in dehumidifier condensate.

Airborne spread of coronavirus disease 2019 (COVID-19) by infectious aerosol is all but certain. However, easily implemented approaches to assess the actual environmental threat are currently unavailable. We present a simple approach with the potential to rapidly provide information about the prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the atmosphere at any location. We used a portable dehumidifier as a readily available and affordable tool to collect airborne virus in the condensate. The dehumidifiers were deployed in selected locations of a hospital ward with patients reporting flu-like symptoms which could possibly be due to COVID-19 over three separate periods of one week. Samples were analyzed frequently for both virus envelope protein and SARS-CoV-2 RNA. In several samples across separate deployments, condensate from dehumidifiers tested positive for the presence of SARS-CoV-2 antigens as confirmed using two independent assays. RNA was detected, but not attributable to SARS-CoV-2. We verified the ability of the dehumidifier to rapidly collect aerosolized sodium chloride. Our results point to a facile pool testing method to sample air in any location in the world and assess the presence and concentration of an infectious agent to obtain quantitative risk assessment of exposure, designate zones as "hot spots" and minimize the need for individual testing which may often be time consuming, expensive, and laborious.

pH-Sensitive Nanodrug Carriers for Codelivery of ERK Inhibitor and Gemcitabine Enhance the Inhibition of Tumor Growth in Pancreatic Cancer.

Pancreatic ductal adenocarcinoma (PDAC), a metabolic disorder, remains one of the leading cancer mortality sources worldwide. An initial response to treatments, such as gemcitabine (GEM), is often followed by emergent resistance reflecting an urgent need for alternate therapies. The PDAC resistance to GEM could be due to ERK1/2 activity. However, successful ERKi therapy is hindered due to low ligand efficiency, poor drug delivery, and toxicity. In this study, to overcome these limitations, we have designed pH-responsive nanoparticles (pHNPs) with a size range of 100-150 nm for the simultaneous delivery of ERKi (SCH 772984) and GEM with tolerable doses. These pHNPs are polyethylene glycol (PEG)-containing amphiphilic polycarbonate block copolymers with tertiary amine side chains. They are systemically stable and capable of improving in vitro and in vivo drug delivery at the cellular environment's acidic pH. The functional analysis indicates that the nanomolar doses of ERKi or GEM significantly decreased the 50% growth inhibition (IC50) of PDAC cells when encapsulated in pHNPs compared to free drugs. The combination of ERKi with GEM displayed a synergistic inhibitory effect. Unexpectedly, we uncover that the minimum effective dose of ERKi significantly promotes GEM activities on PDAC cells. Furthermore, we found that pHNP-encapsulated combination therapy of ERKi with GEM was superior to unencapsulated combination drug therapy. Our findings, thus, reveal a simple, yet efficient, drug delivery approach to overcome the limitations of ERKi for clinical applications and present a new model of sensitization of GEM by ERKi with no or minimal toxicity.

Chemical Architecture of Block Copolymers Differentially Abrogate Cardiotoxicity and Maintain the Anticancer Efficacy of Doxorubicin.

The molecular architecture of pH-responsive amphiphilic block copolymers, their self-assembly behavior to form nanoparticles (NPs), and doxorubicin (DOX)-loading technique govern the extent of DOX-induced cardiotoxicity. We observed that the choice of pH-sensitive tertiary amines, surface charge, and DOX-loading techniques within the self-assembled NPs strongly influence the release and stimulation of DOX-induced cardiotoxicity in primary cardiomyocytes. However, covalent conjugation of DOX to a pH-sensitive nanocarrier through a "conditionally unstable amide" linkage (PCPY-cDOX; PC = polycarbonate and PY = 2-pyrrolidine-1-yl-ethyl-amine) significantly reduced the cardiotoxicity of DOX in cardiomyocytes as compared to noncovalently encapsulated DOX NPs (PCPY-eDOX). When these formulations were tested for drug release in serum-containing media, the PCPY-cDOX systems showed prolonged control over drug release (for ∼72 h) at acidic pH compared to DOX-encapsulated nanocarriers, as expected. We found that DOX-encapsulated nanoformulations triggered cardiotoxicity in primary cardiomyocytes more acutely, while conjugated systems such as PCPY-cDOX prevented cardiotoxicity by disabling the nuclear entry of the drug. Using 2D and 3D (spheroid) cultures of an ER + breast cancer cell line (MCF-7) and a triple-negative breast cancer cell line (MDA-MB-231), we unravel that, similar to encapsulated systems (PCPY-eDOX-type) as reported earlier, the PCPY-cDOX system suppresses cellular proliferation in both cell lines and enhances trafficking through 3D spheroids of MDA-MB-231 cells. Collectively, our studies indicate that PCPY-cDOX is less cardiotoxic as compared to noncovalently encapsulated variants without compromising the chemotherapeutic properties of the drug. Thus, our studies suggest that the appropriate selection of the nanocarrier for DOX delivery may prove fruitful in shifting the balance between low cardiotoxicity and triggering the chemotherapeutic potency of DOX.

Targeting the Tumor Core: Hypoxia-Responsive Nanoparticles for the Delivery of Chemotherapy to Pancreatic Tumors.

In pancreatic ductal adenocarcinoma (PDAC), early onset of hypoxia triggers remodeling of the extracellular matrix, epithelial-to-mesenchymal transition, increased cell survival, the formation of cancer stem cells, and drug resistance. Hypoxia in PDAC is also associated with the development of collagen-rich, fibrous extracellular stroma (desmoplasia), resulting in severely impaired drug penetration. To overcome these daunting challenges, we created polymer nanoparticles (polymersomes) that target and penetrate pancreatic tumors, reach the hypoxic niches, undergo rapid structural destabilization, and release the encapsulated drugs. In vitro studies indicated a high cellular uptake of the polymersomes and increased cytotoxicity of the drugs under hypoxia compared to unencapsulated drugs. The polymersomes decreased tumor growth by nearly 250% and significantly increased necrosis within the tumors by 60% in mice compared to untreated controls. We anticipate that these polymer nanoparticles possess a considerable translational potential for delivering drugs to solid hypoxic tumors.

A New, Simple and Versatile Strategy for the Synthesis of Short Segments of Zigzag-Type Carbon Nanotubes.

Short segments of zigzag single-walled carbon nanotubes (SWCNTs) were obtained from a calixarene scaffold by using a completely new, simple and expedited strategy that allowed fine-tuning of their diameters. This new approach also allows for functionalised short segments of zigzag SWCNTs to be obtained; a prerequisite towards their lengthening. These new SWCNT short segments/calixarene composites show interesting behaviour in solution. DFT analysis of these new compounds also suggests interesting photophysical behaviour. Along with the synthesis of various SWCNTs segments, this approach also constitutes a powerful tool for the construction of new, radially oriented π systems.

Context-Responsive Nanoparticle Derived from Synthetic Zwitterionic Ionizable Phospholipids in Targeted CRISPR/Cas9 Therapy for Basal-like Breast Cancer.

The majority of triple negative breast cancers (TNBCs) are basal-like breast cancers (BLBCs), which tend to be more aggressive, proliferate rapidly, and have poor clinical outcomes. A key prognostic biomarker and regulator of BLBC is the Forkhead box C1 (FOXC1) transcription factor. However, because of its functional placement inside the cell nucleus and its structural similarity with other related proteins, targeting FOXC1 for therapeutic benefit, particularly for BLBC, continues to be difficult. We envision targeted nonviral delivery of CRISPR/Cas9 plasmid toward the efficacious knockdown of FOXC1. Keeping in mind the challenges associated with the use of CRISPR/Cas9 in vivo, including off-targeting modifications, and effective release of the cargo, a nanoparticle with context responsive properties can be designed for efficient targeted delivery of CRISPR/Cas9 plasmid. Consequently, we have designed, synthesized, and characterized a zwitterionic amino phospholipid-derived transfecting nanoparticle for delivery of CRISPR/Cas9. The construct becomes positively charged only at low pH, which encourages membrane instability and makes it easier for nanoparticles to exit endosomes. This has enabled effective in vitro and in vivo downregulation of protein expression and genome editing. Following this, we have used EpCAM aptamer to make the system targeted toward BLBC cell lines and to reduce its off-target toxicity. The in vivo efficacy, biodistribution, preliminary pharmacokinetics, and biosafety of the optimized targeted CRISPR nanoplatform is then validated in a rodent xenograft model. Overall, we have attempted to knockout the proto-oncogenic FOXC1 expression in BLBC cases by efficient delivery of CRISPR effectors via a context-responsive nanoparticle delivery system derived from a designer lipid derivative. We believe that the nonviral approach for in vitro and in vivo delivery of CRISPR/Cas9 targeted toward FOXC1, studied herein, will greatly emphasize the therapeutic regimen for BLBC.

pH-responsive targeted nanoparticles release ERK-inhibitor in the hypoxic zone and sensitize free gemcitabine in mutant K-Ras-addicted pancreatic cancer cells and mouse model.

Therapeutic options for managing Pancreatic ductal adenocarcinoma (PDAC), one of the deadliest types of aggressive malignancies, are limited and disappointing. Therefore, despite suboptimal clinical effects, gemcitabine (GEM) remains the first-line chemotherapeutic drug in the clinic for PDAC treatment. The therapeutic limitations of GEM are primarily due to poor bioavailability and the development of chemoresistance resulting from the addiction of mutant-K-RAS/AKT/ERK signaling-mediated desmoplastic barriers with a hypoxic microenvironment. Several new therapeutic approaches, including nanoparticle-assisted drug delivery, are being investigated by us and others. This study used pH-responsive nanoparticles encapsulated ERK inhibitor (SCH772984) and surface functionalized with tumor-penetrating peptide, iRGD, to target PDAC tumors. We used a small molecule, SCH772984, to target ERK1 and ERK2 in PDAC and other cancer cells. This nanocarrier efficiently released ERKi in hypoxic and low-pH environments. We also found that the free-GEM, which is functionally weak when combined with nanoencapsulated ERKi, led to significant synergistic treatment outcomes in vitro and in vivo. In particular, the combination approaches significantly enhanced the GEM effect in PDAC growth inhibition and prolonged survival of the animals in a genetically engineered KPC (LSL-KrasG12D/+/LSL-Trp53R172H/+/Pdx-1-Cre) pancreatic cancer mouse model, which is not observed in a single therapy. Mechanistically, we anticipate that the GEM efficacy was increased as ERKi blocks desmoplasia by impairing the production of desmoplastic regulatory factors in PDAC cells and KPC mouse tumors. Therefore, 2nd generation ERKi (SCH 772984)-iRGD-pHNPs are vital for the cellular response to GEM and denote a promising therapeutic target in PDAC with mutant K-RAS.

Design and Evaluation of Nanoscale Materials with Programmed Responsivity towards Epigenetic Enzymes.

Self-assembled materials capable of modulating their assembly properties in response to specific enzymes play a pivotal role in advancing 'intelligent' encapsulation platforms for biotechnological applications. Here, we introduce a previously unreported class of synthetic nanomaterials that programmatically interact with histone deacetylase (HDAC) as the triggering stimulus for disassembly. These nanomaterials consist of co-polypeptides comprising poly (acetyl L-lysine) and poly(ethylene glycol) blocks. Under neutral pH conditions, they self-assemble into particles. However, their stability is compromised upon exposure to HDACs, depending on enzyme concentration and exposure time. Our investigation, utilizing HDAC8 as the model enzyme, revealed that the primary mechanism behind disassembly involves a decrease in amphiphilicity within the block copolymer due to the deacetylation of lysine residues within the particles' hydrophobic domains. To elucidate the response mechanism, we encapsulated a fluorescent dye within these nanoparticles. Upon incubation with HDAC, the nanoparticle structure collapsed, leading to controlled release of the dye over time. Notably, this release was not triggered by denatured HDAC8, other proteolytic enzymes like trypsin, or the co-presence of HDAC8 and its inhibitor. We further demonstrated the biocompatibility and cellular effects of these materials and conducted a comprehensive computational study to unveil the possible interaction mechanism between enzymes and particles. By drawing parallels to the mechanism of naturally occurring histone proteins, this research represents a pioneering step toward developing functional materials capable of harnessing the activity of epigenetic enzymes such as HDACs.

Controllable self-replicating RNA vaccine delivered intradermally elicits predominantly cellular immunity.

Intradermal delivery of self-replicating RNA (srRNA) is a promising vaccine platform. We have developed an srRNA that functions optimally at around 33°C (skin temperature) and is inactivated at or above 37°C (core body temperature) as a safety switch. This temperature-controllable srRNA (c-srRNA), when tested as an intradermal vaccine against SARS-CoV-2, functions when injected naked without lipid nanoparticles. Unlike most currently available vaccines, c-srRNA vaccines predominantly elicit cellular immunity with little or no antibody production. Interestingly, c-srRNA-vaccinated mice produced antigen-specific antibodies upon subsequent stimulation with antigen protein. Antigen-specific antibodies were also produced when B cell stimulation using antigen protein was followed by c-srRNA booster vaccination. We have thus designed a pan-coronavirus booster vaccine that incorporates both spike-receptor-binding domains as viral surface proteins and evolutionarily conserved nucleoproteins as viral internal proteins, from both severe acute respiratory syndrome coronavirus 2 and Middle East respiratory syndrome coronavirus. c-srRNA may provide a route to activate cellular immunity against a wide variety of pathogens.

A Phase I/II Clinical Trial of Intradermal, Controllable Self-Replicating Ribonucleic Acid Vaccine EXG-5003 against SARS-CoV-2.

mRNA vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have played a key role in reducing morbidity and mortality from coronavirus disease 2019 (COVID-19). We conducted a double-blind, placebo-controlled phase I/II trial to evaluate the safety, tolerability, and immunogenicity of EXG-5003, a two-dose, controllable self-replicating RNA vaccine against SARS-CoV-2. EXG-5003 encodes the receptor binding domain (RBD) of SARS-CoV-2 and was administered intradermally without lipid nanoparticles (LNPs). The participants were followed for 12 months. Forty healthy participants were enrolled in Cohort 1 (5 µg per dose, n = 16; placebo, n = 4) and Cohort 2 (25 µg per dose, n = 16; placebo, n = 4). No safety concerns were observed with EXG-5003 administration. SARS-CoV-2 RBD antibody titers and neutralizing antibody titers were not elevated in either cohort. Elicitation of antigen-specific cellular immunity was observed in the EXG-5003 recipients in Cohort 2. At the 12-month follow-up, participants who had received an approved mRNA vaccine (BNT162b2 or mRNA-1273) >1 month after receiving the second dose of EXG-5003 showed higher cellular responses compared with equivalently vaccinated participants in the placebo group. The findings suggest a priming effect of EXG-5003 on the long-term cellular immunity of approved SARS-CoV-2 mRNA vaccines.

N-gene-complementary antisense-oligonucleotide directed molecular aggregation of dual-colour carbon dots, leading to efficient fluorometric sensing of SARS-COV-2 RNA.

The early stages of the COVID-19 pandemic punctuated the need for rapid, mass testing for early detection of viral infection. Carbon dots are easily synthesized, cost-effective fluorescent nanoparticles whose surface functionalities enable facile conjugation with biorecognition elements suitable for  molecular detection of viral RNA. Herein, we report that a pair of complementary antisense oligonucleotide (ASO) sequences can lead to a highly specific molecular aggregation of dual colour carbon dots (CDs) in the presence of SARS-CoV-2 RNA. The nanoprobes used ASOs highly specific to the N-gene of SARS-COV-2. When the ASOs are conjugated to blue and yellow citric acid-derived CDs, the combination of the ASO-CD pairs facilitates aggregation-induced emission enhancement (AIEE) of the measured fluorescence after hybridization with SARS-CoV-2 RNA. We found the sensor capable of differentiating between MERS-CoV and SARS-CoV-2 samples and was found to have a limit of detection of 81 copies per µL. Additionally, we used dialysis to demonstrate that the change in emission upon aggregation is dependent on the compositional heterogeneity of the conjugated-carbon dot mixture.

Controllable self-replicating RNA vaccine delivered intradermally elicits predominantly cellular immunity.

Intradermal delivery of self-replicating RNA (srRNA) is a promising vaccine platform. Considering that human skin temperature is around 33°C, lower than core body temperature of 37°C, we have developed an srRNA that functions optimally at skin temperature and is inactivated at or above 37°C as a safety switch. This temperature- c ontrollable srRNA (c-srRNA), when tested as an intradermal vaccine against SARS-CoV-2, functions when injected naked without lipid nanoparticles. Unlike most currently available vaccines, c-srRNA vaccines predominantly elicit cellular immunity with little or no antibody production. Interestingly, c-srRNA-vaccinated mice produced antigen-specific antibodies upon subsequent stimulation with antigen protein. Antigen-specific antibodies were also produced when B-cell stimulation using antigen protein was followed by c-srRNA booster vaccination. Using c-srRNA, we have designed a pan-coronavirus booster vaccine that incorporates both spike receptor binding domains as viral surface proteins and evolutionarily conserved nucleoproteins as viral non-surface proteins, from both SARS-CoV-2 and MERS-CoV. It can thereby potentially immunize against SARS-CoV-2, SARS-CoV, MERS-CoV, and their variants. c-srRNA may provide a route to activate cellular immunity against a wide variety of pathogens.

Silicon nanoforms in crop improvement and stress management.

Although, silicon - the second most abundant element in the earth crust could not supersede carbon (C) in the competition of being the building block of life during evolution, yet its presence has been reported in some life forms. In case of the plants, silicon has been reported widely to promote the plant growth under normal as well as stressful situations. Nanoform of silicon is now being explored for its potential to improve plant productivity and its tolerance against various stresses. Silicon nanoparticles (SiNPs) in the form of nanofertilizers, nanoherbicides, nanopesticides, nanosensors and targeted delivery systems, find great utilization in the field of agriculture. However, the mechanisms underlying their uptake by plants need to be deciphered in detail. Silicon nanoformss are reported to enhance plant growth, majorly by improving photosynthesis rate, elevating nutrient uptake and mitigating reactive oxygen species (ROS)-induced oxidative stress. Various studies have reported their ability to provide tolerance against a range of stresses by upregulating plant defense responses. Moreover, they are proclaimed not to have any detrimental impacts on environment yet. This review includes the up-to-date information in context of the eminent role of silicon nanoforms in crop improvement and stress management, supplemented with suggestions for future research in this field.

New side chain design for pH-responsive block copolymers for drug delivery.

New molecular motifs that can act as pH-regulating triggers for amphiphilic, pH-sensitive block copolymers are investigated. Inspired by the mechanism of action of pH-indicators, such as methyl orange, and natural amino acids, we designed these copolymers where either 4-Amino-4'-dimethylaminoazobenzene, AZB (pKa 3.4, an amine derivative of methyl orange), isoleucine, Ile (pKa 2.37 for carboxylic acid), or a statistical mixture of both were appended as side chains to the hydrophobic block to act as pH-triggers. These new side chain motifs were identified with an aim to enhance the self-assembling properties of the block copolymers in terms of particle size and stability, drug encapsulation, and release. As the parent polymer, poly (ethylene) glycol-block- poly (carbonate) (PEG-b-PC) of number average molecular weight 12.1 kDa was used. We observed that PEG-b-PC block copolymers, when engineered with AZB or Ile-type of pH-regulators appended as side chains to PC blocks, formed self-assembled, spherical nanoparticles with hydrodynamic diameters ranging from 114 to 137 nm depending on copolymer composition. Critical aggregation concentrations (CAC) of the block copolymers were found to be governed by the type and content of side chains. We explored the use of these newly designed block copolymer assemblies as drug carriers using gemcitabine (GEM) as a model cytotoxic drug generally used for pancreatic ductal adenocarcinoma (PDAC). We showed that AZB and Ile decorated copolymeric nanocarriers were able to encapsulate GEM at 13.8-28.8 % loading content and release the drug in a pH-dependent pattern. Drug-loaded nanocarriers showed cellular entry into PDAC cells in vitro and were found to exert cytotoxicity against these cells. Neither the block copolymers bearing AZB or Ile-type pH-responsive triggers, nor their self-assembled nanoparticles showed any cytotoxicity at usable concentrations, thereby reflecting the potentials of these molecular motifs for designing stimuli-responsive drug delivery nanosystems.

Unlocking the power of optical imaging in the second biological window: Structuring near-infrared II materials from organic molecules to nanoparticles.

Biomedical imaging techniques play a crucial role in clinical diagnosis, surgical intervention, and prognosis. Fluorescence imaging in the second biological window (second near-infrared [NIR-II]; 1000-1700 nm) has attracted attention recently. NIR-II fluorescence imaging offers unique advantages in terms of reduced photon scattering, deep tissue penetration, high sensitivity, and many others. A host of materials, including small organic molecules, single-walled carbon nanotubes, polymeric and rare-earth-doped nanoparticles, have been explored as NIR-II emitting fluorescent probes. Efficient and viable approaches to design and develop fluorescence probes with tunable photophysical properties without compromising other key features are of paramount importance. Various chemical strategies are explored to increase the quantum yield of these imaging agents without compromising their spatiotemporal resolution, specificity, and tissue penetration capabilities. This review summarizes the strategies implemented to design and synthesize NIR-II emitting nanoparticles and small organic molecule-based fluorescent probes for applications in the biomedical field. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Implantable Materials and Surgical Technologies > Nanoscale Tools and Techniques in Surgery.

CCN5 activation by free or encapsulated EGCG is required to render triple-negative breast cancer cell viability and tumor progression.

Epigallocatechin-3-gallate (EGCG) has been considered an anticancer agent despite conflicting and discrepant bioavailability views. EGCG impairs the viability and self-renewal capacity of triple-negative breast cancer (TNBC) cells and makes them sensitive to estrogen via activating ER-α. Surprisingly, the mechanism of EGCG's action on TNBC cells remains unclear. CCN5/WISP-2 is a gatekeeper gene that regulates viability, ER-α, and stemness in TNBC and other types of cancers. This study aimed to investigate whether EGCG (free or encapsulated in nanoparticles) interacts with the CCN5 protein by emphasizing its bioavailability and enhancing its anticancer effect. We demonstrate that EGCG activates CCN5 to inhibit in vitro cell viability through apoptosis, the sphere-forming ability via reversing TNBC cells' stemness, and suppressing tumor growth in vivo. Moreover, we found EGCG-loaded nanoparticles to be functionally more active and superior in their tumor-suppressing ability than free-EGCG. Together, these studies identify EGCG (free or encapsulated) as a novel activator of CCN5 in TNBC cells and hold promise as a future therapeutic option for TNBC with upregulated CCN5 expression.

Development of Functional Nanomaterials from Wheat Bran Derived Arabinoxylan for Nucleic Acid Delivery.

Wheat bran is a major byproduct of the wheat industry and a rich source of cellulosic and hemicellulosic compounds. We developed a facile and reproducible method to generate functional nanomaterials from wheat bran derived polysaccharide, Arabinoxylan (AX). We first established that AX derived from wheat bran was chemically equivalent to commercially available AX extracted from wheat flour. Through facile chemical modification, positive and negatively charged domains were introduced along AX backbone, which in turn induced local electrostatic and hydrophobic interactions promoting the formation of nanoparticulate structures. The extracted, chemically modified AX was characterized using FTIR, 1H NMR, and elemental analysis. We observed that, while both anionic and cationic AX self-assemble into stable, spherical nanoparticles with a low polydispersity index, the unmodified AX did not exhibit such self-organizational properties. To form functionally active nanomaterials, we further complexed negatively charged CRISPR-Cas9 DNA with cationic AX. Through gel electrophoretic studies, we identified that, at a feed ratio of DNA to AX of 1:15, AX is capable of forming polyplexes with DNA in the form of nanoparticles with an average hydrodynamic diameter of ∼100 nm and surface charge of -1.40 ± 0.91 mV. We envision that chemically modified AX, originally sourced from agricultural waste materials and not from food products, can be used as functional nanomaterials for gene delivery in the agrochemical sector thus catalyzing the circular approach of sustainability.

Dendritic Polyglycerol-Derived Nano-Architectures as Delivery Platforms of Gemcitabine for Pancreatic Cancer.

Dendritic polyglycerol-co-polycaprolactone (PG-co-PCL)-derived block copolymers are synthesized and explored as nanoscale drug delivery platforms for a chemotherapeutic agent, gemcitabine (GEM), which is the cornerstone of therapy for pancreatic ductal adenocarcinoma (PDAC). Current treatment strategies with GEM result in suboptimal therapeutic outcome owing to microenvironmental resistance and rapid metabolic degradation of GEM. To address these challenges, physicochemical and cell-biological properties of both covalently conjugated and non-covalently stabilized variants of GEM-containing PG-co-PCL architectures have been evaluated. Self-assembly behavior, drug loading and release capacity, cytotoxicity, and cellular uptake properties of these constructs in monolayer and in spheroid cultures of PDAC cells are investigated. To realize the covalently conjugated carrier systems, GEM, in conjunction with a tertiary amine, is attached to the polycarbonate block grafted from the PG-co-PCL core. It is observed that pH-dependent ionization properties of these amine side-chains direct the formation of self-assembly of block copolymers in the form of nanoparticles. For non-covalent encapsulation, a facile "solvent-shifting" technique is adopted. Fabrication techniques are found to control colloidal and cellular properties of GEM-loaded nanoconstructs. The feasibility and potential of these newly developed architectures for designing carrier systems for GEM to achieve augmented prognosis for pancreatic cancer are reported.

PEG-b-poly (carbonate)-derived nanocarrier platform with pH-responsive properties for pancreatic cancer combination therapy.

A pH-responsive nanoparticle platform, based on PEG-b-poly (carbonate) block copolymers have been proposed that can respond to low pH as found in many cancer micro- and intracellular environment, including that in pancreatic cancer. The hydrophobic domain, i.e., the poly (carbonate) segment has been substituted with tertiary amine side chains, such as N, N'-dibutylethylenediamine (pKa = 4.0, DB) and 2-pyrrolidin-1-yl-ethyl-amine (pka = 5.4, Py) to generate two different sets of block copolymers namely PEG-DB and PEG-PY systems. These side-chain appended amines promote disassembly of nanoparticles and activation of drug release in response to pH conditions mimicking extra- (pH 6.9-6.5) and intracellular compartments (5.5-4.5, from early endosome to lysosome) of cancer tissues respectively. A frontline chemotherapy used for pancreatic cancer, i.e., gemcitabine (GEM) and a Hedgehog inhibitor (GDC 0449) has been used as the model combination to evaluate the encapsulation and pH-dependent release efficiency of these block copolymers. We found that, depending on the tertiary amine side chains appended to the polycarbonate segment, these block copolymers self-assemble to form nanoparticles with the size range of 100-150 nm (with a critical association concentration value in the order of 10-6 M). We also demonstrated an approach where GEM and GDC 0449-encapsulated PEG-DB and PEG-PY nanoparticles, responsive to two different pH conditions, when mixed at a 1:1 vol ratio, yielded a pH-dependent co-release of the encapsulated contents. We envision that such release behaviour can be exploited to gain spatiotemporal control over drug accumulation in pathological compartments with different pH status. The mixture of pH-responsive nanoparticles was found to suppress pancreatic cancer cell proliferation when loaded with anticancer agents in vitro. Cell-proliferation assay showed that both variants of PEG-b-polycarbonate block copolymers were inherently non-toxic. We have also immobilized iRGD peptide on intracellularly activable PEG-DB systems to augment cellular uptake. These targeted nanoparticles were found to promote selective internalization of particles in pancreatic cancer cells and tumor tissue.

Size-Transformable, Multifunctional Nanoparticles from Hyperbranched Polymers for Environment-Specific Therapeutic Delivery.

Hyperbranched polymer-derived drug nanocarriers have been synthesized that can change sizes selectively in response to pH. These constructs were composed of tertiary amine-conjugated polycarbonate blocks "grafted from" a hyperbranched polyester polyol core. At neutral pH, unprotonated polycarbonate arms stabilized the copolymer aggregates in the form of nanoparticles with hydrodynamic diameters ranging from 150 to 190 nm. Upon lowering of pH, these larger aggregates disassembled into smaller nanoparticles with diameters of 3-5 nm as directed by protonation of tertiary amine side-chains. The pH-dependent reduction of particle sizes was evident by titrimetric, spectroscopic, dynamic light scattering, transmission electron, and atomic force microscopy-based experiments. We observed that these copolymeric nanoparticles could be loaded with dye and drug molecules either by noncovalent encapsulation or by covalent conjugation. A pH-induced disassembly of the aggregates initiated rapid release of the encapsulated payload, but not of the conjugated ones, thus establishing a controlled rate of therapeutic delivery from the nanostructures over an extended period. We envision that such systems can be used for drug delivery applications where nanoparticle sizes critically govern therapeutic efficiency in a vasculature-poor disease microenvironment such as desmoplasia in pancreatic cancer. Hence, we tested the cellular uptake, cytotoxicity, and chemotherapeutic potential of the size-modifiable nanoaggregates using gemcitabine as a model drug in pancreatic cancer setting. We observed that assembled nanoparticles were biocompatible to noncancerous cells, showed pH-dependent effects on cellular uptake as well as promoted accumulation within cancer cells cultured as 3D spheroids. We also found that when conjugated with gemcitabine, the resulting drug-loaded nanoparticles suppressed proliferation of cancer cells. Collectively, the studies suggested that these synthesized, pH-disassembling nanoscale platform will find applications as biomaterials for constructing a size-transformable drug nanocarriers where reduction of size takes effect near localized disease targets in response to microenvironmental triggers.