The blood–brain barrier (BBB) is a highly specialized neurovascular unit, initially described as an intact barrier to prevent toxins, pathogens, and potentially harmful substances from entering the ...brain. An intact BBB is also critical for the maintenance of normal neuronal function. In cerebral vascular diseases and neurological disorders, the BBB can be disrupted, contributing to disease progression. While restoration of BBB integrity serves as a robust biomarker of better clinical outcomes, the restrictive nature of the intact BBB presents a major hurdle for delivery of therapeutics into the brain. Recent studies show that the BBB is actively engaged in crosstalk between neuronal and the circulatory systems, which defines another important role of the BBB: as an interfacing conduit that mediates communication between two sides of the BBB. This role has been subject to extensive investigation for brain‐targeted drug delivery and shows promising results. The dual roles of the BBB make it a unique target for drug development. Here, recent developments and novel strategies to target the BBB for therapeutic purposes are reviewed, from both barrier and carrier perspectives.
Blood–brain barrier (BBB), which separates the blood and the brain, plays a critical protective role in brain homeostasis. However, it is also a formidable barrier for brain‐targeted drug delivery. This review summarizes the key strategies to restore BBB integrity and to penetrate the BBB for drug delivery, in particular, under neuroinflammation conditions.
Fast and reliable DNA sequencing is a long-standing target in biomedical research. Recent advances in graphene-based electrical sensors have demonstrated their unprecedented sensitivity to adsorbed ...molecules, which holds great promise for label-free DNA sequencing technology. To date, the proposed sequencing approaches rely on the ability of graphene electric devices to probe molecular-specific interactions with a graphene surface. Here we experimentally demonstrate the use of graphene field-effect transistors (GFETs) as probes of the presence of a layer of individual DNA nucleobases adsorbed on the graphene surface. We show that GFETs are able to measure distinct coverage-dependent conductance signatures upon adsorption of the four different DNA nucleobases; a result that can be attributed to the formation of an interface dipole field. Comparison between experimental GFET results and synchrotron-based material analysis allowed prediction of the ultimate device sensitivity, and assessment of the feasibility of single nucleobase sensing with graphene.
We designed a unique nanocapsule for efficient single CRISPR-Cas9 capsuling, noninvasive brain delivery and tumor cell targeting, demonstrating an effective and safe strategy for glioblastoma gene ...therapy. Our CRISPR-Cas9 nanocapsules can be simply fabricated by encapsulating the single Cas9/sgRNA complex within a glutathione-sensitive polymer shell incorporating a dual-action ligand that facilitates BBB penetration, tumor cell targeting, and Cas9/sgRNA selective release. Our encapsulating nanocapsules evidenced promising glioblastoma tissue targeting that led to high PLK1 gene editing efficiency in a brain tumor (up to 38.1%) with negligible (less than 0.5%) off-target gene editing in high-risk tissues. Treatment with nanocapsules extended median survival time (68 days versus 24 days in nonfunctional sgRNA-treated mice). Our new CRISPR-Cas9 delivery system thus addresses various delivery challenges to demonstrate safe and tumor-specific delivery of gene editing Cas9 ribonucleoprotein for improved glioblastoma treatment that may potentially be therapeutically useful in other brain diseases.
Celiac disease has advanced from a medical rarity to a highly prevalent disorder. Patients with the disease show varying degrees of chronic inflammation within the small intestine due to an aberrant ...immune response to the digestion of gliadin found in wheat. As a result, cytokines and antibodies are produced in celiac patients that can be used as specific biomarkers for developing diagnostic tests. This review paper describes celiac disease in terms of its etiological cause, pathological effects, current diagnostic tests based on mucosal biopsy, and the genetic basis for the disease. In addition, it discusses the use of gliadin-induced cytokines, antibodies and autoantibodies as a diagnostic tool for celiac disease. Despite good initial results in terms of sensitivity and specificity, when these immunological tests were used on a large scale, even in combination with genetic testing, the results showed lower predictive value. This review addresses that issue and ends with an outlook on future work required to develop diagnostic tests with greater accuracy in predicting celiac disease in the general public, thus avoiding the need for endoscopy and mucosal biopsy.
Functional ligands and polymers have frequently been used to yield target-specific bio-nanoconjugates. Herein, we provide a systematic insight into the effect of the chain length of poly(oligo ...(ethylene glycol) methyl ether acrylate) (POEGMEA) containing polyethylene glycol on the colloidal stability and antibody-conjugation efficiency of nanoparticles. We employed Reversible Addition–Fragmentation Chain Transfer (RAFT) to design diblock copolymers composed of 7 monoacryloxyethyl phosphate (MAEP) units and 6, 13, 35, or 55 OEGMEA units. We find that when the POEGMEA chain is short, the polymer cannot effectively stabilize the nanoparticles, and when the POEGMEA chain is long, the nanoparticles cannot be efficiently conjugated to antibody. In other words, the majority of the carboxylic groups in larger POEGMEA chains are inaccessible to further chemical modification. We demonstrate that the polymer containing 13 OEGMEA units can effectively bind up to 64% of the antibody molecules, while the binding efficiency drops to 50% and 0% for the polymer containing 35 and 55 OEGMEA units. Moreover, flow cytometry assay statistically shows that about 9% of the coupled antibody retained its activity to recognize B220 biomarkers on the B cells. This work suggests a library of stabile, specific, and bioactive lanthanide-doped nanoconjugates for flow cytometry and mass cytometry application.
The design of compartmentalized carriers for advanced drug delivery systems or artificial cells and organelles is of interest for biomedical applications. Herein, a polymer carrier microreactor that ...contains two different classes of subcompartments, multilayered polymer capsules and liposomes, is presented. 50 nm‐diameter liposomes and 300 nm‐diameter polymer capsules are encapsulated into a larger polymer carrier capsule, demonstrating control over the spatial positioning of the subcompartments, which are either ‘membrane‐associated’ or 'free‐floating’ in the aqueous interior. Selective and spatially dependent degradation of the 300 nm‐diameter subcompartments (without destroying the structural integrity of the enzyme‐loaded liposomes) is also shown, by performing an encapsulated enzymatic reaction using the liposomal subcompartments. These findings cover several important aspects toward the development of engineered compartmentalized carrier vessels for the creation of artificial cell mimics or advanced therapeutic delivery systems.
The assembly of a polymer capsule microreactor containing subcompartments of different composition, polymeric capsules and liposomes, is reported. Control over the position of the subcompartments is demonstrated, the polymeric subunits are selectively degraded, and cargo functionality is preserved within the liposomal subunits, as demonstrated through enzymatic reactions.
A great body of evidence suggests that there are retinal functional and structural changes that occur in Alzheimer's disease (AD). However, whether such changes are primary or secondary remains to be ...elucidated. We studied a range of retinal functional and structural parameters in association with AD- specific pathophysiological markers in the double transgenic APP/PS1 and control mice across age.
Electroretinogram (ERG) and optical coherence tomography (OCT) was performed in APP/PS1 and wild type (WT) control mice every 3 months from 3 to 12 months of age. For functional assessment, the a- and b-wave of the ERG, amplitude of oscillatory potentials (OP) and the positive scotopic threshold response (pSTR) were quantified at each time point. For structural assessment, the inner and outer retinal thickness was segmented and measured from OCT scans. Episodic memory was evaluated at 6, 9 and 12 months of age using the novel object recognition test. Amyloid beta (Aβ) distribution in the hippocampus and the retina were visualised at 3, 6 and 12 months of age. Inter- and intra- group analysis was performed to study rate of change for each parameter between the two groups.
Inter-group analysis revealed a significant difference in b-wave and OPs of APP/PS1 compared to WT controls starting from 3 months (
< 0.001). There was also a significant difference in the amplitude of pSTR between the two groups starting from 6 months (
< 0.001). Furthermore, a significant difference in the inner retinal thickness, between the two groups, was observed starting from 9 months (
< 0.001).
We observed an age-related decline in retinal functional and structural parameters in both APP/PS1 and WT controls, however, inter-group analysis revealed that inner retinal functional and structural decline is exacerbated in APP/PS1 mice, and that retinal functional changes precede structural changes in this strain. Further studies are required to confirm whether such phenomenon occurs in humans and if studying retinal functional changes can aid-in early assessment of AD.
The COVID-19 pandemic has changed people’s lives and has brought society to a sudden standstill, with lockdowns and social distancing as the preferred preventative measures. To lift these ...measurements and reduce society’s burden, developing an easy-to-use, rapid, and portable system to detect SARS-CoV-2 is mandatory. To this end, we developed a portable and semi-automated device for SARS-CoV-2 detection based on reverse transcription loop-mediated isothermal amplification followed by a CRISPR/Cas12a reaction. The device contains a heater element mounted on a printed circuit board, a cooler fan, a proportional integral derivative controller to control the temperature, and designated areas for 0.2 mL Eppendorf® PCR tubes. Our system has a limit of detection of 35 copies of the virus per microliter, which is significant and has the capability of being used in crisis centers, mobile laboratories, remote locations, or airports to diagnose individuals infected with SARS-CoV-2. We believe the current methodology that we have implemented in this article is beneficial for the early screening of infectious diseases, in which fast screening with high accuracy is necessary.
A mis-metabolism of transition metals (i.e., copper, iron, and zinc) in the brain has been recognised as a precursor event for aggregation of Amyloid-β plaques, a pathological hallmark of Alzheimer's ...disease (AD). However, imaging cerebral transition metals in vivo can be extremely challenging. As the retina is a known accessible extension of the central nervous system, we examined whether changes in the hippocampus and cortex metal load are also mirrored in the retina. Laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) was used to visualise and quantify the anatomical distribution and load of Cu, Fe, and Zn in the hippocampus, cortex, and retina of 9-month-old Amyloid Precursor Protein/Presenilin 1 (APP/PS1,
= 10) and Wild Type (WT,
= 10) mice. Our results show a similar metal load trend between the retina and the brain, with the WT mice displaying significantly higher concentrations of Cu, Fe, and Zn in the hippocampus (
< 0.05,
< 0.0001,
< 0.01), cortex (
< 0.05,
= 0.18,
< 0.0001) and the retina (
< 0.001,
= 0.01,
< 0.01) compared with the APP/PS1 mice. Our findings demonstrate that dysfunction of the cerebral transition metals in AD is also extended to the retina. This could lay the groundwork for future studies on the assessment of transition metal load in the retina in the context of early AD.
PDF
