Isothermal titration calorimetry analysis of the binding between the maltodextrin binding protein malE of Staphylococcus aureus with maltodextrins of various lengths

Staphylococcus aureus (S. aureus), a Gram-positive bacterium, causes a wide range of infections, and diagnosis at an early stage is challenging. Targeting the maltodextrin transporter has emerged as a promising strategy for imaging bacteria and has been able to image a wide range of bacteria including S. aureus. However, little is known about the maltodextrin transporter in S. aureus, and this prevents new S. aureus specific ligands for the maltodextrin transporter from being developed. In Gram-positive bacteria, including S. aureus, the first step of maltodextrin transport is the binding of the maltodextrin-binding protein malE to maltodextrins. Thus, understanding the binding affinity and characteristics of malE from S. aureus is important to developing efficient maltodextrin-based imaging probes. We evaluated the affinity of malE of S. aureus to maltodextrins of various lengths. MalE of S. aureus (SAmalE) was expressed in E. coli BL21(DE3) and purified by Ni-NTA resin. The affinities of SAmalE to maltodextrins were evaluated with isothermal titration calorimetry. SAmalE has low affinity to maltose but binds to maltotriose and longer maltodextrins up to maltoheptaose with affinities up to Ka = 9.02 ± 0.49 × 105 M-1. SAmalE binding to maltotriose-maltoheptaose was exothermic and fit a single-binding site model. The van't Hoff enthalpy in the binding reaction of SAmalE with maltotriose was 9.9 ± 1.3 kcal/mol, and the highest affinity of SAmalE was observed with maltotetraose with Ka = 9.02 ± 0.49 × 105 M-1. In the plot of ΔH-T*ΔS, the of Enthalpy-Entropy Compensation effect was observed in binding reaction of SAmalE to maltodextrins. Acarbose and maltotetraiol bind with SAmalE indicating that SAmalE is tolerant of modifications on both the reducing and non-reducing ends of maltodextrins. Our results show that unlike ECmalE and similar to the maltodextrin binding protein of Streptococci, SAmalE primarily binds to maltodextrins via hydrogen bonds. This is distinct from the maltodextrin binding protein of Streptococci, SAmalE that binds to maltotetraiol with high affinity. Understanding the binding characteristics and tolerance to maltodextrins modifications by maltodextrin binding proteins will hopefully provide the basis for developing bacterial species-specific maltodextrin-based imaging probes.

Lipid Nanoparticles Deliver mRNA to the Brain after an Intracerebral Injection

Neurological disorders are often debilitating conditions with no cure. The majority of current therapies are palliative rather than disease-modifying; therefore, new strategies for treating neurological disorders are greatly needed. mRNA-based therapeutics have great potential for treating such neurological disorders; however, challenges with delivery have limited their clinical potential. Lipid nanoparticles (LNPs) are a promising delivery vector for the brain, given their safer toxicity profile and higher efficacy. Despite this, very little is known about LNP-mediated delivery of mRNA into the brain. Here, we employ MC3-based LNPs and successfully deliver Cre mRNA and Cas9 mRNA/Ai9 sgRNA to the adult Ai9 mouse brain; greater than half of the entire striatum and hippocampus was found to be penetrated along the rostro-caudal axis by direct intracerebral injections of MC3 LNP mRNAs. MC3 LNP Cre mRNA successfully transfected cells in the striatum (∼52% efficiency) and hippocampus (∼49% efficiency). In addition, we demonstrate that MC3 LNP Cas9 mRNA/Ai9 sgRNA edited cells in the striatum (∼7% efficiency) and hippocampus (∼3% efficiency). Further analysis demonstrates that MC3 LNPs mediate mRNA delivery to multiple cell types including neurons, astrocytes, and microglia in the brain. Overall, LNP-based mRNA delivery is effective in brain tissue and shows great promise for treating complex neurological disorders.

Lung and liver editing by lipid nanoparticle delivery of a stable CRISPR-Cas9 RNP

Lipid nanoparticle (LNP) delivery of CRISPR ribonucleoproteins (RNPs) has the potential to enable high-efficiency in vivo genome editing with low toxicity and an easily manufactured technology, if RNP efficacy can be maintained during LNP production. In this study, we engineered a thermostable Cas9 from Geobacillus stearothermophilus (GeoCas9) using directed evolution to generate iGeoCas9 evolved variants capable of robust genome editing of cells and organs. iGeoCas9s were significantly better at editing cells than wild-type GeoCas9, with genome editing levels >100X greater than those induced by the native GeoCas9 enzyme. Furthermore, iGeoCas9 RNP:LNP complexes edited a variety of cell lines and induced homology-directed repair (HDR) in cells receiving co-delivered single-stranded DNA (ssDNA) templates. Using tissue-selective LNP formulations, we observed genome editing of 35‒56% efficiency in the liver or lungs of mice that received intravenous injections of iGeoCas9 RNP:LNPs. In particular, iGeoCas9 complexed to acid-degradable LNPs edited lung tissue in vivo with an average of 35% efficiency, a significant improvement over editing efficiencies observed previously using viral or non-viral delivery strategies. These results show that thermostable Cas9 RNP:LNP complexes are a powerful alternative to mRNA:LNP delivery vehicles, expanding the therapeutic potential of genome editing.

HIV-1 Remission: Accelerating the Path to Permanent HIV-1 Silencing

Despite remarkable progress, a cure for HIV-1 infection remains elusive. Rebound competent latent and transcriptionally active reservoir cells persevere despite antiretroviral therapy and rekindle infection due to inefficient proviral silencing. We propose a novel "block-lock-stop" approach, entailing long term durable silencing of viral expression towards an irreversible transcriptionally inactive latent provirus to achieve long term antiretroviral free control of the virus. A graded transformation of remnant HIV-1 in PLWH from persistent into silent to permanently defective proviruses is proposed, emulating and accelerating the natural path that human endogenous retroviruses (HERVs) take over millions of years. This hypothesis was based on research into delineating the mechanisms of HIV-1 latency, lessons from latency reversing agents and advances of Tat inhibitors, as well as expertise in the biology of HERVs. Insights from elite controllers and the availability of advanced genome engineering technologies for the direct excision of remnant virus set the stage for a rapid path to an HIV-1 cure.

Gene editing therapeutics based on mRNA delivery

The field of gene editing has received much attention in recent years due to its immense therapeutic potential. In particular, gene editing therapeutics, such as the CRISPR-Cas systems, base editors, and other emerging gene editors, offer the opportunity to address previously untreatable disorders. This review aims to summarize the therapeutic applications of gene editing based on mRNA delivery. We introduce gene editing therapeutics using mRNA and focus on engineering and improvement of gene editing technology. We subsequently examine ex vivo and in vivo gene editing techniques and conclude with an exploration of the next generation of CRISPR and base editing systems.

Mercapto-pyrimidines are reversible covalent inhibitors of the papain-like protease (PLpro) and inhibit SARS-CoV-2 (SCoV-2) replication

The papain-like protease (PLpro) plays a critical role in SARS-CoV-2 (SCoV-2) pathogenesis and is essential for viral replication and for allowing the virus to evade the host immune response. Inhibitors of PLpro have great therapeutic potential, however, developing them has been challenging due to PLpro's restricted substrate binding pocket. In this report, we screened a 115 000-compound library for PLpro inhibitors and identified a new pharmacophore, based on a mercapto-pyrimidine fragment that is a reversible covalent inhibitor (RCI) of PLpro and inhibits viral replication in cells. Compound 5 had an IC50 of 5.1 μM for PLpro inhibition and hit optimization yielded a derivative with increased potency (IC50 0.85 μM, 6-fold higher). Activity based profiling of compound 5 demonstrated that it reacts with PLpro cysteines. We show here that compound 5 represents a new class of RCIs, which undergo an addition elimination reaction with cysteines in their target proteins. We further show that their reversibility is catalyzed by exogenous thiols and is dependent on the size of the incoming thiol. In contrast, traditional RCIs are all based upon the Michael addition reaction mechanism and their reversibility is base-catalyzed. We identify a new class of RCIs that introduces a more reactive warhead with a pronounced selectivity profile based on thiol ligand size. This could allow the expansion of RCI modality use towards a larger group of proteins important for human disease.

In utero delivery of mRNA to the heart, diaphragm and muscle with lipid nanoparticles

Nanoparticle-based drug delivery systems have the potential to revolutionize medicine, but their low vascular permeability and rapid clearance by phagocytic cells have limited their medical impact. Nanoparticles delivered at the in utero stage can overcome these key limitations due to the high rate of angiogenesis and cell division in fetal tissue and the under-developed immune system. However, very little is known about nanoparticle drug delivery at the fetal stage of development. In this report, using Ai9 CRE reporter mice, we demonstrate that lipid nanoparticle (LNP) mRNA complexes can deliver mRNA in utero, and can access and transfect major organs, such as the heart, the liver, kidneys, lungs and the gastrointestinal tract with remarkable efficiency and low toxicity. In addition, at 4 weeks after birth, we demonstrate that 50.99 ± 5.05%, 36.62 ± 3.42% and 23.7 ± 3.21% of myofiber in the diaphragm, heart and skeletal muscle, respectively, were transfected. Finally, we show here that Cas9 mRNA and sgRNA complexed to LNPs were able to edit the fetal organs in utero. These experiments demonstrate the possibility of non-viral delivery of mRNA to organs outside of the liver in utero, which provides a promising strategy for treating a wide variety of devastating diseases before birth.

TAxI-peptide targeted Cas12a ribonuclease protein nanoformulations increase genome editing in hippocampal neurons

Gene therapy approaches that utilize Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) ribonucleases have tremendous potential to treat human disease. However, CRISPR therapies delivered by integrating viral vectors are limited by potential off-target genome editing caused by constitutive activation of ribonuclease functions. Thus, biomaterial formulations are being used for the delivery of purified CRISPR components to increase the efficiency and safety of genome editing approaches. We previously demonstrated that a novel peptide identified by phage display, TAxI-peptide, mediates delivery of recombinant proteins into neurons. In this report we utilized NeutrAvidin protein to formulate neuron-targeted genome-editing nanoparticles. Cas12a ribonucleases was loaded with biotinylated guide RNA and biotinylated TAxI-peptide onto NeutrAvidin protein to coordinate the formation a targeted ribonuclease protein (RNP) complex. TAxI-RNP complexes are polydisperse with a 14.3 nm radius. The nanoparticles are stable after formulation and show good stability in the presence of normal mouse serum. TAxI-RNP nanoparticles increased neuronal delivery of Cas12a in reporter mice, resulting in induced tdTomato expression after direct injection into the dentate gyrus of the hippocampus. TAxI-RNP nanoparticles also increased genome editing efficacy in hippocampal neurons versus glia. These studies demonstrate the ability to assemble RNP nanoformulations with NeutrAvidin by binding biotinylated peptides and gRNA-loaded Cas12a ribonucleases into protein nanoparticles that target CRISPR delivery to specific cell-types in vivo. The potential to deliver CRISPR nanoparticles to specific cell-types and control off-target delivery to further reduce deleterious genome editing is essential for the creation of viable therapies to treat nervous system disease.

A covalent inhibitor targeting the papain-like protease from SARS-CoV-2 inhibits viral replication†

Covalent inhibitors of the papain-like protease (PLpro) from SARS-CoV-2 have great potential as antivirals, but their non-specific reactivity with thiols has limited their development. In this report, we performed an 8000 molecule electrophile screen against PLpro and identified an α-chloro amide fragment, termed compound 1, which inhibited SARS-CoV-2 replication in cells, and also had low non-specific reactivity with thiols. Compound 1 covalently reacts with the active site cysteine of PLpro, and had an IC50 of 18 μM for PLpro inhibition. Compound 1 also had low non-specific reactivity with thiols and reacted with glutathione 1–2 orders of magnitude slower than other commonly used electrophilic warheads. Finally, compound 1 had low toxicity in cells and mice and has a molecular weight of only 247 daltons and consequently has great potential for further optimization. Collectively, these results demonstrate that compound 1 is a promising lead fragment for future PLpro drug discovery campaigns.

Compound 1 is a covalent inhibitor of SARS-CoV-2 PLpro that inhibits viral replication and has low non-specific reactivity with thiols.

The Coiled-Coil Forming Peptide (KVSALKE)5 Is a Cell Penetrating Peptide that Enhances the Intracellular Delivery of Proteins

Protein-based therapeutics have the potential to treat a variety of diseases, however, safe and effective methods for delivering them into cells need to be developed before their clinical potential can be realized. Peptide fusions have great potential for improving intracellular delivery of proteins. However, very few peptides have been identified that can increase the intracellular delivery of proteins, and new peptides that can enhance intracellular protein delivery are greatly needed. In this report, the authors demonstrate that the coiled-coil forming peptide (KVSALKE)₅ (termed K5) can function as a cell penetrating peptide (CPP), and can also complex other proteins that contain its partner peptide E5. It is shown here that GFP and Cas9 fused to the K5 peptide has dramatically enhanced cell uptake in a variety of cell lines, and is able to edit neurons and astrocytes in the striatum and hippocampus of mice after a direct intracranial injection. Collectively, these studies demonstrate that the coiled-coil forming peptide (KVSALKE)₅ is a new class of multifunctional CPPs that has great potential for improving the delivery of proteins into cells and in vivo.

A self-immolative linker that releases thiols detects penicillin amidase and nitroreductase with high sensitivity via absorption spectroscopy

This article reports the synthesis and characterization of a novel self-immolative linker, based on thiocarbonates, which releases a free thiol upon activation via enzymes. We demonstrate that thiocarbonate self-immolative linkers can be used to detect the enzymes penicillin G amidase (PGA) and nitroreductase (NTR) with high sensitivity using absorption spectroscopy. Paired with modern thiol amplification technology, the detection of PGA and NTR were achieved at concentrations of 160 nM and 52 nM respectively. In addition, the PGA probe was shown to be compatible with both biological thiols and enzymes present in cell lysates.

Acid-Sensitive Surfactants Enhance the Delivery of Nucleic Acids

The development of endosomal disruptive agents is a major challenge in the field of drug delivery and pharmaceutical chemistry. Current endosomal disruptive agents are composed of polymers, peptides, and nanoparticles and have had limited clinical impact. Alternatives to traditional endosomal disruptive agents are therefore greatly needed. In this report, we introduce a new class of low molecular weight endosomal disruptive agents, termed caged surfactants, that selectively disrupt endosomes via reversible PEGylation under acidic endosomal conditions. The caged surfactants have the potential to address several of the limitations hindering the development of current endosomal disruptive agents, such as high toxicity and low excretion, and are amenable to traditional medicinal chemistry approaches for optimization. In this report, we synthesized three generations of caged surfactants and demonstrated that they can enhance the ability of cationic lipids to deliver mRNA into primary cells. We also show that caged surfactants can deliver siRNA into cells when modified with the RNA-binding dye thiazole orange. We anticipate that the caged surfactants will have numerous applications in pharmaceutical chemistry and drug delivery given their versatility.

Dimensionless parameter predicts bacterial prodrug success

Understanding mechanisms of antibiotic failure is foundational to combating the growing threat of multidrug-resistant bacteria. Prodrugs-which are converted into a pharmacologically active compound after administration-represent a growing class of therapeutics for treating bacterial infections but are understudied in the context of antibiotic failure. We hypothesize that strategies that rely on pathogen-specific pathways for prodrug conversion are susceptible to competing rates of prodrug activation and bacterial replication, which could lead to treatment escape and failure. Here, we construct a mathematical model of prodrug kinetics to predict rate-dependent conditions under which bacteria escape prodrug treatment. From this model, we derive a dimensionless parameter we call the Bacterial Advantage Heuristic (BAH) that predicts the transition between prodrug escape and successful treatment across a range of time scales (1-104  h), bacterial carrying capacities (5 × 104 -105  CFU/µl), and Michaelis constants (KM  = 0.747-7.47 mM). To verify these predictions in vitro, we use two models of bacteria-prodrug competition: (i) an antimicrobial peptide hairpin that is enzymatically activated by bacterial surface proteases and (ii) a thiomaltose-conjugated trimethoprim that is internalized by bacterial maltodextrin transporters and hydrolyzed by free thiols. We observe that prodrug failure occurs at BAH values above the same critical threshold predicted by the model. Furthermore, we demonstrate two examples of how failing prodrugs can be rescued by decreasing the BAH below the critical threshold via (i) substrate design and (ii) nutrient control. We envision such dimensionless parameters serving as supportive pharmacokinetic quantities that guide the design and administration of prodrug therapeutics.

Screening a Library of FDA-Approved and Bioactive Compounds for Antiviral Activity against SARS-CoV-2

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19), has emerged as a major global health threat. The COVID-19 pandemic has resulted in over 168 million cases and 3.4 million deaths to date, while the number of cases continues to rise. With limited therapeutic options, the identification of safe and effective therapeutics is urgently needed. The repurposing of known clinical compounds holds the potential for rapid identification of drugs effective against SARS-CoV-2. Here, we utilized a library of FDA-approved and well-studied preclinical and clinical compounds to screen for antivirals against SARS-CoV-2 in human pulmonary epithelial cells. We identified 13 compounds that exhibit potent antiviral activity across multiple orthogonal assays. Hits include known antivirals, compounds with anti-inflammatory activity, and compounds targeting host pathways such as kinases and proteases critical for SARS-CoV-2 replication. We identified seven compounds not previously reported to have activity against SARS-CoV-2, including B02, a human RAD51 inhibitor. We further demonstrated that B02 exhibits synergy with remdesivir, the only antiviral approved by the FDA to treat COVID-19, highlighting the potential for combination therapy. Taken together, our comparative compound screening strategy highlights the potential of drug repurposing screens to identify novel starting points for development of effective antiviral mono- or combination therapies to treat COVID-19.

Antibiotic Cross-linked Micelles with Reduced Toxicity for Multidrug-Resistant Bacterial Sepsis Treatment

One potential approach to address the rising threat of antibiotic resistance is through novel formulations of established drugs. We designed antibiotic cross-linked micelles (ABC-micelles) by cross-linking the Pluronic F127 block copolymers with an antibiotic itself, via a novel one-pot synthesis in aqueous solution. ABC-micelles enhanced antibiotic encapsulation while also reducing systemic toxicity in mice. Using colistin, a hydrophilic, potent ″last-resort" antibiotic, ABC-micelle encapsulation yield was 80%, with good storage stability. ABC-micelles exhibited an improved safety profile, with a maximum tolerated dose of over 100 mg/kg colistin in mice, at least 16 times higher than the free drug. Colistin-induced nephrotoxicity and neurotoxicity were reduced in ABC-micelles by 10-50-fold. Despite reduced toxicity, ABC-micelles preserved bactericidal activity, and the clinically relevant combination of colistin and rifampicin (co-loaded in the micelles) showed a synergistic antimicrobial effect against antibiotic-resistant strains of Escherichia coli, Pseudomonas aeruginosa, and Acinetobacter baumannii. In a mouse model of sepsis, colistin ABC-micelles showed equivalent efficacy as free colistin but with a substantially higher therapeutic index. Microscopic single-cell imaging of bacteria revealed that ABC-micelles could kill bacteria in a more rapid manner with distinct cell membrane disruption, possibly reflecting a different antimicrobial mechanism from free colistin. This work shows the potential of drug cross-linked micelles as a new class of biomaterials formed from existing antibiotics and represents a new and generalized approach for formulating amine-containing drugs.

Maltohexaose-indocyanine green (MH-ICG) for near infrared imaging of endocarditis

Infectious endocarditis is a life-threatening disease, and diagnostics are urgently needed to accurately diagnose this disease especially in the case of prosthetic valve endocarditis. We show here that maltohexaose conjugated to indocyanine green (MH-ICG) can detect Staphylococcus aureus (S. aureus) infection in a rat model of infective endocarditis. The affinity of MH-ICG to S. aureus was determined and had a Km and Vmax of 5.4 μM and 3.0 X 10⁻⁶ μmol/minutes/10⁸ CFU, respectively. MH-ICG had no detectable toxicity to mammalian cells at concentrations as high as 100 μM. The in vivo efficiency of MH-ICG in rats was evaluated using a right heart endocarditis model, and the accumulation of MH-ICG in the bacterial vegetations was 2.5 ± 0.2 times higher than that in the control left ventricular wall. The biological half-life of MH-ICG in healthy rats was 14.0 ± 1.3 minutes, and approximately 50% of injected MH-ICG was excreted into the feces after 24 hours. These data demonstrate that MH-ICG was internalized by bacteria with high specificity and that MH-ICG specifically accumulated in bacterial vegetations in a rat model of endocarditis. These results demonstrate the potential efficacy of this agent in the detection of infective endocarditis.

A rapid, antibiotic susceptibility test for multidrug-resistant, Gram-negative bacterial uropathogens using the biochemical assay, DETECT

The increasing prevalence of extended spectrum β-lactamases (ESBLs) and plasmid-mediated AmpC (pAmpC) β-lactamases among Enterobacterales threatens our ability to treat urinary tract infections (UTIs). These organisms are resistant to most β-lactam antibiotics and are frequently multidrug-resistant (MDR). Consequently, they are often resistant to antibiotics used to empirically treat UTIs. The lack of rapid diagnostic and antibiotic susceptibility tests (AST) makes clinical management of UTIs caused by such organisms difficult, as standard culture and susceptibility assays require several days. We have adapted a biochemical detection assay, termed dual-enzyme trigger-enabled cascade technology (DETECT) for rapid detection of resistance (time-to-result of 3 h) to other antibiotics commonly used in treatment of UTIs. DETECT is activated by the presence of CTX-M and pAmpC β-lactamases. In this proof-of-concept study, the adapted DETECT assay (AST-DETECT) has been performed on pure-cultures of Klebsiella pneumoniae and Escherichia coli (48 isolates) expressing ESBL or pAmpC β-lactamases to perform AST for ciprofloxacin (sensitivity 96.9%, specificity 100%, accuracy 97.9%) nitrofurantoin (sensitivity 95.7%, specificity 91.7%, accuracy 94%) and trimethoprim/sulfamethoxazole (sensitivity 83.3%, specificity 100%, accuracy 89.4%). These results suggest that AST-DETECT may be adapted as a potential diagnostic platform to rapidly detect multidrug-resistant E. coli and K. pneumoniae that cause UTI.

Advances in Imaging Reactive Oxygen Species

Reactive oxygen species (ROS) play a pivotal role in many cellular processes and can be either beneficial or harmful. The design of ROS-sensitive fluorophores has allowed for imaging of specific activity and has helped elucidate mechanisms of action for ROS. Understanding the oxidative role of ROS in the many roles it plays allows us to understand the human body. This review provides a concise overview of modern advances in the field of ROS imaging. Indeed, much has been learned about the role of ROS throughout the years; however, it has recently been shown that using nanoparticles, rather than individual small organic fluorophores, for ROS imaging can further our understanding of ROS.

Non-viral strategies for delivering genome editing enzymes

Genome-editing tools such as Cre recombinase (Cre), zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and most recently the clustered regularly interspaced short palindromic repeat (CRISPR)-associated protein system have revolutionized biomedical research, agriculture, microbial engineering, and therapeutic development. Direct delivery of genome editing enzymes, as opposed to their corresponding DNA and mRNA precursors, is advantageous since they do not require transcription and/or translation. In addition, prolonged overexpression is a problem when delivering viral vector or plasmid DNA which is bypassed when delivering whole proteins. This lowers the risk of insertional mutagenesis and makes for relatively easier manufacturing. However, a major limitation of utilizing genome editing proteins in vivo is their low delivery efficiency, and currently the most successful strategy involves using potentially immunogenic viral vectors. This lack of safe and effective non-viral delivery systems is still a big hurdle for the clinical translation of such enzymes. This review discusses the challenges of non-viral delivery strategies of widely used genome editing enzymes, including Cre recombinase, ZFNs and TALENs, CRISPR/Cas9, and Cas12a (Cpf1) in their protein format and highlights recent innovations of non-viral delivery strategies which have the potential to overcome current delivery limitations and advance the clinical translation of genome editing.

A pH-sensitive eosin-block copolymer delivers proteins intracellularly

There is great interest in developing strategies to deliver proteins into the cytoplasm of cells. We report here a PEG-poly-eosin block copolymer (PEG-pEosin) that can encapsulate proteins and release them in active form under mildly acidic conditions. A PEG-pEosin formulation composed of Cre and the endosomolytic protein LLO efficiently performed gene editing in cells and in the brains of mice after an intracranial injection.

A Dual Enzyme-Based Biochemical Test Rapidly Detects Third-Generation Cephalosporin-Resistant CTX-M-Producing Uropathogens in Clinical Urine Samples

Extended-spectrum β-lactamase (ESBL)-producing Gram-negative bacteria (GNB) are increasingly identified as the cause of both community and healthcare-associated urinary tract infections (UTIs), with CTX-Ms being the most common ESBLs identified. CTX-M-producing GNB are resistant to most β-lactam antibiotics and are frequently multidrug-resistant, which limits treatment options. Rapid diagnostic tests that can detect ESBL-producing GNB, particularly CTX-M producers, in the urine of patients with UTIs are needed. Results from such a test could direct the selection of appropriate antimicrobial therapy at the point-of-care (POC). In this study, we show that a chromogenic, dual enzyme-mediated amplification system (termed DETECT [dual-enzyme trigger-enabled cascade technology]) can identify CTX-M-producing GNB from unprocessed urine samples in 30 minutes. We first tested DETECT against a diverse set of recombinant β-lactamases and β-lactamase-producing clinical isolates to elucidate its selectivity. We then tested DETECT with 472 prospectively collected clinical urine samples submitted for urine culture to a hospital clinical microbiology laboratory. Of these, 118 (25%) were consistent with UTI, 13 (11%) of which contained ESBL-producing GNB. We compared DETECT results in urine against a standard phenotypic method to detect ESBLs, and polymerase chain reaction and sequencing for CTX-M genes. DETECT demonstrated 90.9% sensitivity and 97.6% specificity (AUC, 0.937; 95% confidence interval, 0.822-1.000), correctly identifying 10 of 11 urine samples containing a clinically significant concentration of CTX-M-producing GNB (including Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis). Our results demonstrate the clinical potential of DETECT to deliver diagnostic information at the POC, which could improve initial antibiotic selection.

A traceless linker for aliphatic amines that rapidly and quantitatively fragments after reduction

Reduction sensitive linkers (RSLs) have the potential to transform the field of drug delivery due to their ease of use and selective cleavage in intracellular environments. However, despite their compelling attributes, developing reduction sensitive self-immolative linkers for aliphatic amines has been challenging due to their poor leaving group ability and high pK_a values. Here a traceless self-immolative linker composed of a dithiol-ethyl carbonate connected to a benzyl carbamate (DEC) is presented, which can modify aliphatic amines and release them rapidly and quantitatively after disulfide reduction. DEC was able to reversibly modify the lysine residues on CRISPR–Cas9 with either PEG, the cell penetrating peptide Arg₁₀, or donor DNA, and generated Cas9 conjugates with significantly improved biological properties. In particular, Cas9–DEC–PEG was able to diffuse through brain tissue significantly better than unmodified Cas9, making it a more suitable candidate for genome editing in animals. Furthermore, conjugation of Arg₁₀ to Cas9 with DEC was able to generate a self-delivering Cas9 RNP that could edit cells without transfection reagents. Finally, conjugation of donor DNA to Cas9 with DEC increased the homology directed DNA repair (HDR) rate of the Cas9 RNP by 50% in HEK 293T cell line. We anticipate that DEC will have numerous applications in biotechnology, given the ubiquitous presence of aliphatic amines on small molecule and protein therapeutics.

Reduction sensitive linkers (RSLs) have the potential to transform the field of drug delivery due to their ease of use and selective cleavage in intracellular environments.

The delivery challenge: fulfilling the promise of therapeutic genome editing

Genome editing has the potential to treat an extensive range of incurable monogenic and complex diseases. In particular, advances in sequence-specific nuclease technologies have dramatically accelerated the development of therapeutic genome editing strategies that are based on either the knockout of disease-causing genes or the repair of endogenous mutated genes. These technologies are progressing into human clinical trials. However, challenges remain before the therapeutic potential of genome editing can be fully realized. Delivery technologies that have serendipitously been developed over the past couple decades in the protein and nucleic acid delivery fields have been crucial to genome editing success to date, including adeno-associated viral and lentiviral vectors for gene therapy and lipid nanoparticle and other non-viral vectors for nucleic acid and protein delivery. However, the efficiency and tissue targeting capabilities of these vehicles must be further improved. In addition, the genome editing enzymes themselves need to be optimized, and challenges regarding their editing efficiency, specificity and immunogenicity must be addressed. Emerging protein engineering and synthetic chemistry approaches can offer solutions and enable the development of safe and efficacious clinical genome editing.

A cephalosporin-chemiluminescent conjugate increases beta-lactamase detection sensitivity by four orders of magnitude

The expression of beta-lactamases in bacteria is a central cause of drug resistance. In this report, we present a beta-lactamase chemiluminescent probe, termed CCP, which can for the first time detect beta-lactamase activity via chemiluminescence and can detect beta lactamase with a sensitivity that is 4-orders of magnitude higher than the commercially available fluorescent lactamase substrate fluorocillin.

The methionase chain reaction: an enzyme-based autocatalytic amplification system for the detection of thiols

We present an autocatalytic system for the detection and amplification of thiols termed the Methionase Chain Reaction (MCR). MCR is based on the reversible modification of the thiol producing enzyme Methionine Gamma-Lyase (MGL). MCR was able to amplify the concentration of thiols by a factor of 560 and was able to visually detect thiols at concentrations as low as 50 nM.

Detection of unamplified target genes via CRISPR-Cas9 immobilized on a graphene field-effect transistor

Most methods for the detection of nucleic acids require many reagents and expensive and bulky instrumentation. Here, we report the development and testing of a graphene-based field-effect transistor that uses clustered regularly interspaced short palindromic repeats (CRISPR) technology to enable the digital detection of a target sequence within intact genomic material. Termed CRISPR-Chip, the biosensor uses the gene-targeting capacity of catalytically deactivated CRISPR-associated protein 9 (Cas9) complexed with a specific single-guide RNA and immobilized on the transistor to yield a label-free nucleic-acid-testing device whose output signal can be measured with a simple handheld reader. We used CRISPR-Chip to analyse DNA samples collected from HEK293T cell lines expressing blue fluorescent protein, and clinical samples of DNA with two distinct mutations at exons commonly deleted in individuals with Duchenne muscular dystrophy. In the presence of genomic DNA containing the target gene, CRISPR-Chip generates, within 15 min, with a sensitivity of 1.7 fM and without the need for amplification, a significant enhancement in output signal relative to samples lacking the target sequence. CRISPR-Chip expands the applications of CRISPR-Cas9 technology to the on-chip electrical detection of nucleic acids.

A novel fluorescent surfactant enhances the delivery of the Cas9 ribonucleoprotein and enables the identification of edited cells

In this report, we designed and synthesized a novel fluorescent single tailed surfactant (termed FEDS), which can disrupt endosomes, complex lipofectamine, and can also identify cells that have been transfected. FEDS was able to increase the gene editing efficiency of lipofectamine/Cas9 ribonucleoprotein by 300% via a combination of fluorescent based enrichment and endosomal disruption.

A multiplexed, indirect enzyme-linked immunoassay for the detection and differentiation of E. coli from other Enterobacteriaceae and P. aeruginosa from other glucose non-fermenters

Gram-negative bacteria (GNB) are important causes of community (CA) and hospital (HA)- associated infections. Here we describe the development of an indirect ELISA (I-ELISA), which can be used to detect and differentiate the Enterobacteriaceae Escherichia coli, and glucose non-fermenter Pseudomonas aeruginosa from other GNB species. The I-ELISA utilizes six antibodies for bacterial speciation, which were grouped according to their bacterial targets; Enterobacteriaceae (SL-EntA and CH1810 mAb), Escherichia coli (SL-EcA and 6103-46 mAb), Pseudomonas aeruginosa (SL-PaA and SL-PaB). The six, anti-GNB antibodies were first screened against a panel of well-characterized clinical GNB isolates to optimize assay conditions and to determine individual antibody sensitivity and specificity. When tested against a diverse, blinded panel of 94 GNB clinical isolates, the I-ELISA exhibited the following sensitivity/specificity for each target: Enterobacteriaceae (94.4%/95%), E. coli (82.6%/88.7%), P. aeruginosa (83.3%/96%). An I-ELISA to detect and differentiate the most common GNB pathogens offers advantage in terms of simplicity over diagnostic tests currently used in most clinical settings.

Making gene editing a therapeutic reality

This review discusses current bottlenecks in making CRISPR-Cas9-mediated genome editing a therapeutic reality and it outlines recent strategies that aim to overcome these hurdles as well as the scope of current clinical trials that pioneer the medical translation of CRISPR-Cas9. Additionally, this review outlines the specifics of disease-modifying gene editing in recessive versus dominant genetic diseases with the focus on genetic myopathies that are exemplified by Duchenne muscular dystrophy and myotonic dystrophies.

Graphene-based biosensor for on-chip detection of bio-orthogonally labeled proteins to identify the circulating biomarkers of aging during heterochronic parabiosis

Studies of heterochronic parabiosis, where two animals of different ages are joined surgically, provided proof-of-principle results that systemic proteins have broad age-specific effects on tissue health and repair. In an effort to identify these systemic proteins, we previously developed a method to selectively label the proteome of only one animal joined in parabiosis utilizing bio-orthogonal non-canonical amino acid tagging (BONCAT), which can metabolically label proteins during their de novo synthesis by incorporating a methionine substitute, azido-nor-leucine (ANL), in cells expressing a mutant methionyl-tRNA synthetase (MetRSL274G). Once labeled, we can selectively identify the proteins produced by the MetRSL274G transgenic mouse in the setting of heterochronic parabiosis. This approach enabled the detection of several rejuvenating protein candidates from the young parabiont, which were transferred to the old mammalian tissue through their shared circulation. Although BONCAT is a very powerful technology, the challenges associated with its complexity including large starting material requirements and cost of ANL-labeled protein detection, such as modified antibody arrays and mass spectrometry, limit its application. Herein, we propose a lab-on-a-chip technology, termed Click-A+Chip for facile and rapid digital detection of ANL-labeled proteomes present in minute amount of sample, to replace conventional assays. Click-A+Chip is a graphene-based field effect biosensor (gFEB) which utilizes novel on-chip click-chemistry to specifically bind to ANL-labeled biomolecules. In this study, Click-A+Chip is utilized for the capture of ANL-labeled proteins transferred from young to old parabiotic mouse partners. Moreover, we were able to identify the young-derived ANL-labeled Lif-1 and leptin in parabiotic systemic milieu, confirming previous data as well as providing novel findings on the relative levels of these factors in young versus old parabionts. Summarily, our results demonstrate that Click-A+Chip can be used for rapid detection and identification of ANL-labeled proteins, significantly reducing the sample size, complexity, cost and time associated with BONCAT analysis.

An Enzyme-Mediated Amplification Strategy Enables Detection of β-Lactamase Activity Directly in Unprocessed Clinical Samples for Phenotypic Detection of β-Lactam Resistance

Biochemical assays that can identify β-lactamase activity directly from patient samples have the potential to significantly improve the treatment of bacterial infections. However, current β-lactamase probes do not have the sensitivity needed to measure β-lactam resistance directly from patient samples. Here, we report the development of an instrument-free signal amplification technology, DETECT, that connects the activity of two enzymes in series to effectively amplify the activity of β-lactamase 40 000-fold, compared to the standard β-lactamase probe nitrocefin.

Extension of the crRNA enhances Cpf1 gene editing in vitro and in vivo

Engineering of the Cpf1 crRNA has the potential to enhance its gene editing efficiency and non-viral delivery to cells. Here, we demonstrate that extending the length of its crRNA at the 5' end can enhance the gene editing efficiency of Cpf1 both in cells and in vivo. Extending the 5' end of the crRNA enhances the gene editing efficiency of the Cpf1 RNP to induce non-homologous end-joining and homology-directed repair using electroporation in cells. Additionally, chemical modifications on the extended 5' end of the crRNA result in enhanced serum stability. Also, extending the 5' end of the crRNA by 59 nucleotides increases the delivery efficiency of Cpf1 RNP in cells and in vivo cationic delivery vehicles including polymer nanoparticle. Thus, 5' extension and chemical modification of the Cpf1 crRNA is an effective method for enhancing the gene editing efficiency of Cpf1 and its delivery in vivo.

Nitro Sulfonyl Fluorides are a new pharmacophore for the development of antibiotics

The development of antibiotics against Gram-negative bacteria is a central problem in drug discovery. In this report, we demonstrate that aromatic sulfonyl fluorides with a nitro group in their ortho position have remarkable antibacterial activity and are active against drug-resistant pathogens, such as methicillin-resistant Staphylococcus aureus (MRSA), multidrug resistant Acinetobacter baumannii, and Pseudomonas aeruginosa.

A peptide-based fluorescent probe images ERAAP activity in cells and in high throughput assays

ERAAP is an intracellular amino-peptidase that plays a central role in determining the repertoire of peptides displayed by cells by MHC class I molecules, and dysfunctions in ERAAP are linked to a variety of diseases. There is therefore great interest in developing probes that can image ERAAP in cells. In this report we present a fluorescent probe, termed Ep, that can image ERAAP activity in live cells. Ep is composed of a 10 amino acid ERAAP substrate that has a donor quencher pair conjugated to it, composed of BODIPY and dinitro-toluene. Ep undergoes a 20-fold increase in fluorescence after ERAAP cleavage, and was able to image ERAAP activity in cell culture via fluorescence microscopy. In addition, we used Ep to develop a high throughput screen for ERAAP inhibitors, and screened an electrophile library containing 1460 compounds. From this Ep based screen we identified aromatic alkyne-ketone as a lead fragment that can irreversibly inhibit ERAAP activity. We anticipate numerous applications of Ep given its unique ability to image ERAAP within cells.

A Trimethoprim Conjugate of Thiomaltose Has Enhanced Antibacterial Efficacy In Vivo

Trimethoprim is one of the most widely used antibiotics in the world. However, its efficacy is frequently limited by its poor water solubility and dose limiting toxicity. Prodrug strategies based on conjugation of oligosaccharides to trimethoprim have great potential for increasing the solubility of trimethoprim and lowering its toxicity, but they have been challenging to develop due to the sensitivity of trimethoprim to chemical modifications, and the rapid degradation of oligosaccharides in serum. In this report, we present a trimethoprim conjugate of maltodextrin termed TM-TMP, which increased the water solubility of trimethoprim by over 100 times, was stable to serum enzymes, and was active against urinary tract infections in mice. TM-TMP is composed of thiomaltose conjugated to trimethoprim, via a self-immolative disulfide linkage, and releases 4'-OH-trimethoprim (TMP-OH) after disulfide cleavage, which is a known metabolic product of trimethoprim and is as potent as trimethoprim. TM-TMP also contains a new maltodextrin targeting ligand composed of thiomaltose, which is stable to hydrolysis by serum amylases and therefore has the metabolic stability needed for in vivo use. TM-TMP has the potential to significantly improve the treatment of a wide number of infections given its high water solubility and the widespread use of trimethoprim.

Novel PET and Near Infrared Imaging Probes for the Specific Detection of Bacterial Infections Associated With Cardiac Devices

OBJECTIVES

The aim of this study was to develop imaging agents to detect early stage infections in implantable cardiac devices.

BACKGROUND

Bacteria ingest maltodextrins through the specific maltodextrin transporter. We developed probes conjugated with either a fluorescent dye (maltohexaose fluorescent dye probe [MDP]) or a F-18 (F18 fluoromaltohexaose) and determined their usefulness in a model of infections associated with implanted cardiac devices.

METHODS

Stainless steel mock-ups of medical devices were implanted subcutaneously in rats. On post-operative day 4, animals were injected with either Staphylococcus aureus around the mock-ups to induce a relatively mild infection or oil of turpentine to induce noninfectious inflammation. Animals with a sterile implant were used as control subjects. On post-operative day 6, either the MDP or F18 fluoromaltohexaose was injected intravenously, and the animals were scanned with the appropriate imaging device. Additional positron emission tomography imaging studies were performed with F18-fluorodeoxyglucose as a comparison of the specificity of our probes (n = 5 to 9 per group).

RESULTS

The accumulation of the MDP in the infected rats was significantly increased at 1 h after injection when compared with the control and noninfectious inflammation groups (intensity ratio 1.54 ± 0.07 vs. 1.26 ± 0.04 and 1.20 ± 0.05, respectively; p < 0.05) and persisted for more than 24 h. In positron emission tomography imaging, both F18 fluoromaltohexaose and F18 fluorodeoxyglucose significantly accumulated in the infected area 30 min after the injection (maximum standard uptake value ratio 4.43 ± 0.30 and 4.87 ± 0.28, respectively). In control rats, there was no accumulation of imaging probes near the device. In the noninfectious inflammation rats, no significant accumulation was observed with F18 fluoromaltohexaose, but F18 fluorodeoxyglucose accumulated in the mock-up area (maximum standard uptake value 2.53 ± 0.39 vs. 4.74 ± 0.46, respectively; p < 0.05).

CONCLUSIONS

Our results indicate that maltohexaose-based imaging probes are potentially useful for the specific and sensitive diagnosis of infections associated with implantable cardiac devices.

Recent developments in intracellular protein delivery

Protein therapeutics based on transcription factors, gene editing enzymes, signaling proteins and protein antigens, have the potential to provide cures for a wide number of untreatable diseases, but cannot be developed into therapeutics due to challenges in delivering them into the cytoplasm. There is therefore great interest in developing strategies that can enable proteins to enter the cytoplasm of cells. In this review article we will discuss recent progress in intracellular protein therapeutics, which are focused on the following four classes of therapeutics, Firstly, vaccine development, secondly, transcription factor therapies, thirdly, gene editing and finally, cancer therapeutics. These exciting new advances raise the prospect of developing cures for several un-treatable diseases.

A Cleavage-Responsive Stem-Loop Hairpin for Assaying Guide RNA Activity

The scope of the CRISPR-Cas9 technology now reaches far beyond genomic engineering. While significant efforts are driving the evolution of this revolutionary biomedical tool, the in vitro cleavage assay remains the standard method implemented to validate the guide RNA that directs endonuclease Cas9 to a desired genomic target. Here, we report the development of an alternative guide RNA validation system called GUIDER. GUIDER features a hairpin loop structure with a proximal guanosine-rich unit, a distal fluorophore unit, and a gRNA-targeting stem component. Cleavage of GUIDER by its complementary RNA-guided Cas9 endonuclease complex yields a fluorescent emission at 525 nm, signaling effective cleavage of the hairpin structure. GUIDER was validated using the model gene target mpcsk9, and it was able to identify the gRNA that could most efficiently cleave the target mpcsk9 gene. The modular design of GUIDER should allow it to have broad applicability in validating gRNAs, and its fluorescent signal output offers a rapid, simple, and quantitative measure of Cas9-mediated DNA cleavage.

Thiophene bridged aldehydes (TBAs) image ALDH activity in cells via modulation of intramolecular charge transfer

Aldehyde dehydrogenases (ALDHs) catalyze the oxidation of an aldehyde to a carboxylic acid and are implicated in the etiology of numerous diseases. However, despite their importance, imaging ALDH activity in cells is challenging due to a lack of fluorescent imaging probes. In this report, we present a new family of fluorescent probes composed of an oligothiophene flanked by an aldehyde and an electron donor, termed thiophene-bridged aldehydes (TBAs), which can image ALDH activity in cells. The TBAs image ALDH activity via a fluorescence sensing mechanism based on the modulation of intramolecular charge transfer (ICT) and this enables the TBAs and their ALDH-mediated oxidized products, thiophene-bridged carboxylates (TBCs), to have distinguishable fluorescence spectra. Herein, we show that the TBAs can image ALDH activity in cells via fluorescence microscopy, flow cytometry, and in a plate reader. Using TBA we were able to develop a cell-based high throughput assay for ALDH inhibitors, for the first time, and screened a large, 1460-entry electrophile library against A549 cells. We identified α,β-substituted acrylamides as potent electrophile fragments that can inhibit ALDH activity in cells. These inhibitors sensitized drug-resistant glioblastoma cells to the FDA approved anti-cancer drug, temozolomide. The TBAs have the potential to make the analysis of ALDH activity in cells routinely possible given their ability to spectrally distinguish between an aldehyde and a carboxylic acid.

Aptavalve-gated Mesoporous Carbon Nanospheres image Cellular Mucin and provide On-demand Targeted Drug Delivery

In this report, we present a mesoporous carbon nanosphere that can target drugs to tumors and image tumor biomarkers. A single-strand DNA (P₀ aptamer) aptavalve was capped on the surface of doxorubicin-loaded oxide mesoporous carbon nanospheres (Dox-OMCN-P₀) through π-π stacking for real-time imaging-guided on-demand targeting drug delivery. The Dox-OMCN-P₀ could not only realize the detection of MUC1 tumor marker with a wide linear range (0.1 - 10.6 μmol/L) and a low detection limit (17.5 nmol) based on different apparatuses, but also achieve in-situ targeting imaging of cellular MUC1 concentration in vitro and in vivo via "off-on" fluorescence biosensing. Much attractively, as a real-time feedback of the diagnostic/imaging outcomes, Dox-OMCN-P₀ accomplished the on-demand targeting drug delivery in quantitative response to MUC1. Controllable chemotherapy with sustained release and pH-sensitiveness, together with the potential photothermal therapy, were also clearly demonstrated. This is a simple but advanced platform, which could well achieve the real-time switchable imaging of cellular mucin for targeting cancer therapy.

Synthetically modified guide RNA and donor DNA are a versatile platform for CRISPR-Cas9 engineering

Chemical modification of the gRNA and donor DNA has great potential for improving the gene editing efficiency of Cas9 and Cpf1, but has not been investigated extensively. In this report, we demonstrate that the gRNAs of Cas9 and Cpf1, and donor DNA can be chemically modified at their terminal positions without losing activity. Moreover, we show that 5' fluorescently labeled donor DNA can be used as a marker to enrich HDR edited cells by a factor of two through cell sorting. In addition, we demonstrate that the gRNA and donor DNA can be directly conjugated together into one molecule, and show that this gRNA-donor DNA conjugate is three times better at transfecting cells and inducing HDR, with cationic polymers, than unconjugated gRNA and donor DNA. The tolerance of the gRNA and donor DNA to chemical modifications has the potential to enable new strategies for genome engineering.

End-point immobilization of heparin on plasma-treated surface of electrospun polycarbonate-urethane vascular graft

Small-diameter synthetic vascular grafts have high failure rate due to primarily surface thrombogenicity, and effective surface chemical modification is critical to maintain the patency of the grafts. In this study, we engineered a small-diameter, elastic synthetic vascular graft with off-the-shelf availability and anti-thrombogenic activity. Polycarbonate-urethane (PCU), was electrospun to produce nanofibrous grafts that closely mimicked a native blood vessel in terms of structural and mechanical strength. To overcome the difficulty of adding functional groups to PCU, we explored various surface modification methods, and determined that plasma treatment was the most effective method to modify the graft surface with functional amine groups, which were subsequently employed to conjugate heparin via end-point immobilization. In addition, we confirmed in vitro that the combination of plasma treatment and end-point immobilization of heparin exhibited the highest surface density and correspondingly the highest anti-thrombogenic activity of heparin molecules. Furthermore, from an in vivo study using a rat common carotid artery anastomosis model, we showed that plasma-heparin grafts had higher patency rate at 2weeks and 4weeks compared to plasma-control (untreated) grafts. More importantly, we observed a more complete endothelialization of the luminal surface with an aligned, well-organized monolayer of endothelial cells, as well as more extensive graft integration in terms of vascularization and cell infiltration from the surrounding tissue. This work demonstrates the feasibility of electrospinning PCU as synthetic elastic material to fabricate nanofibrous vascular grafts, as well as the potential to endow desired functionalization to the graft surface via plasma treatment for the conjugation of heparin or other bioactive molecules.

STATEMENT OF SIGNIFICANCE

Vascular occlusion remains the leading cause of death all over the world, despite advances made in balloon angioplasty and conventional surgical intervention. Currently, autografts are the gold-standard grafts used to treat vascular occlusive disease. However, many patients with vascular occlusive disease do not have autologous vascular graft available. Therefore, there is a widely recognized need for a readily available, functional, small-diameter vascular graft (inner diameter of <6mm). This work addresses this critical need by developing a method of antithrombogenic modification of synthetic grafts.

An oral microjet vaccination system elicits antibody production in rabbits

Noninvasive immunization technologies have the potential to revolutionize global health by providing easy-to-administer vaccines at low cost, enabling mass immunizations during pandemics. Existing technologies such as transdermal microneedles are costly, deliver drugs slowly, and cannot generate mucosal immunity, which is important for optimal immunity against pathogens. We present a needle-free microjet immunization device termed MucoJet, which is a three-dimensional microelectromechanical systems-based drug delivery technology. MucoJet is administered orally, placed adjacent to the buccal tissue within the oral cavity, and uses a self-contained gas-generating chemical reaction within its two-compartment plastic housing to produce a high-pressure liquid jet of vaccine. We show that the vaccine jet ejected from the MucoJet device is capable of penetrating the buccal mucosal layer in silico, in porcine buccal tissue ex vivo, and in rabbits in vivo. Rabbits treated with ovalbumin by MucoJet delivery have antibody titers of anti-ovalbumin immunoglobulins G and A in blood serum and buccal tissue, respectively, that are three orders of magnitude higher than rabbits receiving free ovalbumin delivered topically by a dropper in the buccal region. MucoJet has the potential to accelerate the development of noninvasive oral vaccines, given its ability to elicit antibody production that is detectable locally in the buccal tissue and systemically via the circulation.

Thiophene bridged hydrocyanine – a new fluorogenic ROS probe

In this report, we present a new hydrocyanine analog, termed as thiophene-bridged hydrocyanine (TBHC), which has its double bonds replaced with a bisthiophene, is 8.06-fold more stable to auto-oxidation than hydro-Cy5 and significantly better in cell culture.

Hydrogel Pore-Size Modulation for Enhanced Single-Cell Western Blotting

Pore-gradient microgel arrays enable thousands of parallel high-resolution single-cell protein electrophoresis separations for targets accross a wide molecular mass (25-289 kDa), yet within 1 mm separation distances. Dual crosslinked hydrogels facilitate gel-pore expansion after electrophoresis for efficient and uniform immunoprobing. The photopatterned, light-activated, and acid-expandable hydrogel underpins single-cell protein analysis, here for oncoprotein-related signaling in human breast biopsy.

In Vivo Imaging of Retinal Oxidative Stress Using a Reactive Oxygen Species-Activated Fluorescent Probe

PURPOSE

In vivo methods for detecting oxidative stress in the eye would improve screening and monitoring of the leading causes of blindness: diabetic retinopathy, glaucoma, and age-related macular degeneration.

METHODS

To develop an in vivo biomarker for oxidative stress in the eye, we tested the efficacy of a reactive oxygen species (ROS)-activated, near-infrared hydrocyanine-800CW (H-800CW) fluorescent probe in light-induced retinal degeneration (LIRD) mouse models. After intravitreal delivery in LIRD rats, fluorescent microscopy was used to confirm that the oxidized H-800CW appeared in the same retinal layers as an established ROS marker (dichlorofluorescein).

RESULTS

Dose-response curves of increasing concentrations of intravenously injected H-800CW demonstrated linear increases in both intensity and total area of fundus hyperfluorescence in LIRD mice, as detected by scanning laser ophthalmoscopy. Fundus hyperfluorescence also correlated with the duration of light damage and functional deficits in vision after LIRD. In LIRD rats with intravitreal injections of H-800CW, fluorescent labeling was localized to photoreceptor inner segments, similar to dichlorofluorescein.

CONCLUSIONS

Hydrocyanine-800CW detects retinal ROS in vivo and shows potential as a novel biomarker for ROS levels in ophthalmic diseases.

Physical Delivery of Macromolecules using High-Aspect Ratio Nanostructured Materials

There is great need for the development of an efficient delivery method of macromolecules, including nucleic acids, proteins, and peptides, to cell cytoplasm without eliciting toxicity or changing cell behavior. High-aspect ratio nanomaterials have addressed many challenges present in conventional methods, such as cell membrane passage and endosomal degradation, and have shown the feasibility of efficient high-throughput macromolecule delivery with minimal perturbation of cells. This review describes the recent advances of in vitro and in vivo physical macromolecule delivery with high-aspect ratio nanostructured materials and summarizes the synthesis methods, material properties, relevant applications, and various potential directions.