Epidemiology of Reportable Bacterial Infectious Diseases in Saudi Arabia

INTRODUCTION

Bacterial infections have a significant impact on human health; they can cause severe morbidity and mortality, particularly in susceptible populations. Epidemiological surveillance is a critical tool for monitoring the population's health and facilitate the prevention and control of infectious disease outbreaks. Knowing the burden of bacterial communicable diseases is an initial core step toward public health goals.

METHODS

Saudi epidemiology surveillance data were utilized to depict the changing epidemiology of bacterial infectious diseases in Saudi Arabia from 2018 to 2021. The cumulative numbers of cases, demographics, and incidence rates were analyzed and visualized. Parametric tests were used to compare the difference in the mean values between categorical variables. Regression analysis was employed to estimate trends in disease rates over time. Statistical significance was set at p value ≤ 0.05.

RESULTS

The results revealed that brucellosis, tuberculosis, and salmonellosis were the most frequently reported bacterial infectious diseases in Saudi Arabia. Males were more significantly affected by brucellosis and tuberculosis infections than females. Salmonellosis infections were more significant among Saudi citizens, while pulmonary tuberculosis was more significant in non-Saudis. Interestingly, there was a decline in the incidence rates of numerous bacterial infectious diseases during the Coronavirus Disease 2019 (COVID-19) pandemic and COVID-19 restrictions. Some bacterial infectious diseases were rarely reported in Saudi Arabia, including syphilis and diphtheria.

CONCLUSIONS

The future perspective of this research is to enhance disease surveillance reporting by including different variables, such as the source of infection, travel history, hospitalization, and mortality rates. The aim is to improve the sensitivity and specificity of surveillance data and focus on the mortality associated with bacterial pathogens to identify the most significant threats and set a public health priority.

Mitochondrial DNA variation in Aedes aegypti (Diptera: Culicidae) mosquitoes from Jeddah, Saudi Arabia

Wolbachia (Hertig 1936) (Rickettsiales: Ehrlichiaceae) has emerged as a valuable biocontrol tool in the fight against dengue by suppressing the transmission of the virus through mosquitoes. Monitoring the dynamics of Wolbachia is crucial for evaluating the effectiveness of release programs. Mitochondrial (mtDNA) markers serve as important tools for molecular tracking of infected mitochondrial backgrounds over time but require an understanding of the variation in release sites. In this study, we investigated the mitochondrial lineages of Aedes aegypti (Linnaeus 1762) in Jeddah, Saudi Arabia, which is a prospective release site for the "wAlbBQ" Wolbachia-infected strain of this mosquito species. We employed a combination of comprehensive mitogenomic analysis (including all protein-coding genes) and mtDNA marker analysis (cox1 and nad5) using data collected from Jeddah. We combined our mitogenome and mtDNA marker data with those from previous studies to place mitochondrial variation in Saudi Arabia into a broader global context. Our findings revealed the presence of 4 subclades that can be broadly categorized into 2 major mitochondrial lineages. Ae. aegypti mosquitoes from Jeddah belonged to both major lineages. Whilst mitogenomic data offered a higher resolution for distinguishing Jeddah mosquitoes from the wAlbBQ strain, the combination of cox1 and nad5 mtDNA markers alone proved to be sufficient. This study provides the first important characterization of Ae. aegypti mitochondrial lineages in Saudi Arabia and offers essential baseline information for planning future molecular monitoring efforts during the release of Wolbachia-infected mosquitoes.

Recent Advancement in mRNA Vaccine Development and Applications

Messenger RNA (mRNA) vaccine development for preventive and therapeutic applications has evolved rapidly over the last decade. The mRVNA vaccine has proven therapeutic efficacy in various applications, including infectious disease, immunotherapy, genetic disorders, regenerative medicine, and cancer. Many mRNA vaccines have made it to clinical trials, and a couple have obtained FDA approval. This emerging therapeutic approach has several advantages over conventional methods: safety; efficacy; adaptability; bulk production; and cost-effectiveness. However, it is worth mentioning that the delivery to the target site and in vivo degradation and thermal stability are boundaries that can alter their efficacy and outcomes. In this review, we shed light on different types of mRNA vaccines, their mode of action, and the process to optimize their development and overcome their limitations. We also have explored various delivery systems focusing on the nanoparticle-mediated delivery of the mRNA vaccine. Generally, the delivery system plays a vital role in enhancing mRNA vaccine stability, biocompatibility, and homing to the desired cells and tissues. In addition to their function as a delivery vehicle, they serve as a compartment that shields and protects the mRNA molecules against physical, chemical, and biological activities that can alter their efficiency. Finally, we focused on the future considerations that should be attained for safer and more efficient mRNA application underlining the advantages and disadvantages of the current mRNA vaccines.

Assessment of Proinflammatory Cytokines Among Patients with Middle East Respiratory Syndrome Coronavirus Infection

Middle East respiratory syndrome coronavirus (MERS-CoV) is associated with significant morbidity and mortality. This study was performed to assess the proinflammatory cytokines profile among MERS-CoV patients. A total of 46 MERS-CoV-infected patients (27 symptomatic and 19 asymptomatic) were assessed and compared with 52 normal healthy controls for plasma levels of interleukin (IL)-1β, tumor necrosis factor (TNF)-α, IL-17, IL-7, IL-6, interferon (IFN)-α, and IL-15 using a customized luminex kit. Whereas asymptomatic MERS-CoV patients and controls were no different; the mean plasma levels among MERS-CoV symptomatic patients were significantly higher than the normal controls: IL-1β (16.89 ± 1.23 vs. 12.80 ± 0.59 pg/mL; p < 0.001), TNF-α (14.04 ± 0.93 vs. 10.35 ± 0.29 pg/mL; p < 0.0001), IL-17 (14.3 ± 0.89 vs. 11.47 ± 0.61 pg/mL; p < 0.001), IL-7 (21.56 ± 1.00 vs. 16.31 ± 0.30 pg/mL; p < 0.0001), IL-6 (156.5 ± 37.90 vs. 18.60 ± 1.59 pg/mL; p < 0.0001), and IFN-α (68.73 ± 13.06 vs. 23.57 ± 1.05 pg/mL; p < 0.0001). The mean plasma levels of IL-7 (24.81 ± 1.63 vs. 19.79 ± 0.94 pg/mL; p < 0.01), IL-6 (312.7 ± 94.67 vs. 101.2 ± 25.67 pg/mL; p < 0.01), and IFN-α (89.00 ± 18.97 vs. 51.05 ± 8.68 pg/mL; p < 0.05) were significantly elevated among MERS-CoV symptomatic patients with fatal outcome compared with MERS-CoV symptomatic patients who survived. Only IL-7 was found to have a higher risk ratio of mortality (4.76, 95% confidence interval: 1.5-14.94; p < 0.01). No differences were observed in IL-15 levels among the groups. Significantly elevated proinflammatory cytokines among symptomatic MERS-CoV-infected patients may contribute to manifestations of cytokine storm frequently observed among critically ill MERS-CoV patients and IL-7 may serve as a marker for disease activity.

Application of CRISPR/Cas9 Technology in Cancer Treatment: A Future Direction

Gene editing, especially with clustered regularly interspaced short palindromic repeats associated protein 9 (CRISPR-Cas9), has advanced gene function science. Gene editing's rapid advancement has increased its medical/clinical value. Due to its great specificity and efficiency, CRISPR/Cas9 can accurately and swiftly screen the whole genome. This simplifies disease-specific gene therapy. To study tumor origins, development, and metastasis, CRISPR/Cas9 can change genomes. In recent years, tumor treatment research has increasingly employed this method. CRISPR/Cas9 can treat cancer by removing genes or correcting mutations. Numerous preliminary tumor treatment studies have been conducted in relevant fields. CRISPR/Cas9 may treat gene-level tumors. CRISPR/Cas9-based personalized and targeted medicines may shape tumor treatment. This review examines CRISPR/Cas9 for tumor therapy research, which will be helpful in providing references for future studies on the pathogenesis of malignancy and its treatment.

Insights from the molecular docking analysis of SGLT2 and FIMH to combat uropathogenicity

SGLT2 inhibitors are a novel class of FDA approved anti-diabetes drugs. They act by blocking the SGLT2 protein, which prevents glucose reabsorption, leading in enhance glucose excretion and lower blood glucose levels. In diabetic patients, SGLT2 inhibitors have been linked to urinary tract infections (UTIs). Therefore, the development of novel SGLT2 inhibitors with no adverse effects is a need of time. With this purpose, in this study, 48164natural compounds from ZINC database were screened targeting both the SGLT2 and FimH protein using insilico approaches. FimH has been discovered as a promising target for preventing and treating UTIs. The hit compounds ZINC69481892, ZINC1612996, and ZINC4039265 exhibited strong binding with both SGLT2 and FimH with binding energies values of -9.88, -8.96, and -10.57 kcal/mol for SGLT2, and -7.86, -7.01, and -8.92 kcal/mol for FimH, which is higher than that of controls (-6.78 kcal/mol (Empaglifozolin for SGLT2) and -5.14 kcal/mol (Heptyl α-d-mannopyranoside for FimH)). Hits were found to bind with key residues of both SGLT2 and FimH protein. In addition, physiochemical properties showed that these compounds have good drug-likeness properties. Therefore, we anticipate that if these compounds are investigated further, might be potential SGLT2 inhibitors with less uropathogenic adverse effects.

Spatio-Temporal Modelling Informing Wolbachia Replacement Releases in a Low Rainfall Climate

Releases of Aedes aegypti carrying Wolbachia bacteria are known to suppress arbovirus transmission and reduce the incidence of vector-borne diseases. In planning for Wolbachia releases in the arid environment of Jeddah, Saudi Arabia, we collected entomological data with ovitraps across a 7-month period in four locations. Herein, we show that mosquito presence in basements does not differ from that of non-basement areas of buildings. In modelling mosquito presence across the study sites, we found the spatial structure to be statistically significant in one of the four sites, while a significant spatial structure was found for egg production data across three of the four sites. The length scales of the spatial covariance functions fitted to the egg production data ranged from 143 m to 574 m, indicating that high productivity regions can be extensive in size. Rank-correlation analyses indicated that mosquito presence tended to persist from the dry to wet season, but that egg production ranks at locations could reverse. The data suggest that, in Jeddah, the quality of the local environment for breeding can vary over time. The data support the feasibility of dry season releases but with release numbers needing to be flexible depending on local rates of invasion.

The short-term effect of different chlorhexidine forms versus povidone iodine mouth rinse in minimizing the oral SARS-CoV-2 viral load: An open label randomized controlled clinical trial study

Several investigations evaluated the possibility of different types of mouth wash rinse in minimizing the SARS-CoV-2 load. However, results still controversial. The study aim is to assess the short-term efficiency of several over-the-counter mouth rinses and lozenges in minimizing the salivary viral load for SARS-CoV-2 in patients with confirmed COVID-19 in comparison to saline. This is a randomized controlled clinical trial with 4 arms. The recruited cases were randomized using a simple randomization technique and were assigned to chlorhexidine digluconate mouth rinse (CHX mouth rinse), 2 mg of chlorhexidine digluconate lozenges (CHX lozenges), povidone iodine mouth rinse (PVP-I mouth rinse) or saline as a control group. Saliva were collected from all study subjects by passive drool technique at two time points. First, prior to intervention with mouth rinse or the lozenges, the baseline saliva sample was collected. Second saliva samples were collected immediately after the mouth rinse. Real time PCR was conducted and the value threshold cycle (Ct) for each sample was recorded. Majority of the participants had an education level of high school or less (60%), were married (68.3), males (58.3%), and non-smokers (58.5%). No statistically significant differences between groups at the two times test (P > .05). However, a significant decrease of salivary viral load in all four groups combined (P-value for E genes = .027, and for S genes = .006), and in PVP-I mouth rinse specifically (P = .003 and P = .045, respectively). Povidone iodine mouth rinse showed a potential influence on the reduction of the viral load on a short-term basis. However, longer-term studies of the effect of these products should be conducted.

Oral gel loaded with penciclovir-lavender oil nanoemulsion to enhance bioavailability and alleviate pain associated with herpes labialis

Herpes labialis, caused by herpes simplex virus type 1, is usually characterized by painful skin or mucosal lesions. Penciclovir (PV) tablets are found to be effective against herpes labialis but suffer from poor oral bioavailability. This study aimed to combine the benefits of PV and lavender oil (LO), which exhibits anesthetic activity, in the form of a self-nanoemulsifying drug delivery system (SNEDDS) for the treatment of herpes labialis. Toward this purpose, LO (oil), Labrasol:Labrafil M1944 CS in the ratio of 6:4 (surfactant mixture), and Lauroglycol-FCC (co-surfactant, selected based on the solubility of PV) were evaluated as the independent factors using a distance quadratic mixture design. The formulation was optimized for the minimum globule size and maximum stability index and was determined to contain 14% LO, 40.5% Labrasol:Labrafil 1944 (6:4), and 45.5% Lauroglycol-FCC. The optimized PV-LO-SNEDDS was embedded in chitosan hydrogel and the resulting formulations coded by (O3) were prepared and evaluated. The rheological studies demonstrated a combined pseudoplastic and thixotropic behavior with the highest flux of PV permeation across sheep buccal mucosa. Compared to a marketed 1% PV cream, the O3 formulation exhibited a significantly higher and sustained PV release, nearly twice the PV permeability, and a relative bioavailability of 180%. Overall, results confirm that the O3 formulation can provide an efficient delivery system for PV to reach oral mucosa and subsequent prolonged PV release. Thus, the PV-LO-SNEDDS embedded oral gel is promising and can be further evaluated in clinical settings to establish its therapeutic use in herpes labialis.

Contemporary Ross procedure outcomes: medium- to long-term results in 214 patients

OBJECTIVE

Our goal was to present 2 decades of our experience with the Ross procedure and its sequential modifications, adopted since 2010, to improve the reoperation rate.

METHODS

We performed a single-centre, retrospective review of database information and medical notes about the implantation technique: the freestanding root. We compared era 1 (1997-2009) and era 2 (2010-2019).

RESULTS

Between 1997 and 2019, a total of 214 Ross procedures were performed (71% men, median age 24 years) [interquartile range (IQR) 15-38]. Of these, 87% had various forms of congenital-dysplastic aortic valves. The median cross-clamping and bypass times were 173 (IQR 148-202) and 202 (IQR 182-244) min. The median postoperative stay was 6 days (2-77). Thirty-day mortality was 0.5%. The median follow-up time was 8.2 years (IQR 3.9-13.2). Survival at 10 and 20 years was 97% and 95%; freedom from greater than moderate aortic regurgitation or aortic valve intervention was 91% and 80%; and 93% of the patients were in New York Heart Association functional class I. Twenty (21%) patients operated on during era 1 and 6 (9%) during era 2 underwent autograft reoperations. The median follow-up time was 14.3 (IQR 11.5-17.4) and 4.8 (IQR 2.5-7) years. Freedom from autograft reoperation was 87% and 69% at 10 and 20 years, with no significant difference between eras. Freedom from homograft reoperation was 96% and 76% at 10 and 20 years. The presence of aortic regurgitation, infective endocarditis and era 1 were predictors of autograft reoperation. Male gender and era 1 were predictors of neoaortic root dilatation.

CONCLUSIONS

The contemporary modified Ross procedure continues to deliver excellent results and should remain part of the strategy to treat children and young adults requiring aortic valve replacement.

CRISPR technology: new paradigm to target the infectious disease pathogens

OBJECTIVE

Infectious diseases are one of the prime causes of death worldwide. An innovative sequence specific editing technology "Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)" has been tested on a broad range of microorganisms to target and destroy invading foreign DNA to human cells or tissues. This study aimed to discuss the mechanism and therapeutic usage of CRISPR/Cas9 genome editing technology in the management of various infectious disease pathogens.

MATERIALS AND METHODS

We conducted a broad search of the English-language literature in "PubMed" using the search terms "CRISPR", "Cas-9", "Genome editing", "Gene therapy", "infectious disease pathogens". All the articles were reviewed and required information was recorded.

RESULTS

CRISPR technology is used to modify and modulate the gene expression in biomedical research and therapeutic development. This technology facilitates the understanding of fundamental biology and broadens the horizon of treatments of germ-laden conditions.

CONCLUSIONS

The applications of CRISPR technology are widely established in the diagnosis and treatment of various bacterial, viral, fungal and parasitic infectious diseases. CRISPR technology is a simple, efficient and tested on a broad range of microorganisms to rectify disease-associated genetic defects and destroy invading foreign DNA to human cells or tissues.

Middle East Respiratory Syndrome Coronavirus (MERS-CoV) infection: epidemiology, pathogenesis and clinical characteristics

OBJECTIVE

Middle East Respiratory Syndrome Coronavirus-(MERS-CoV) infection is an evolving worldwide health crisis. The early diagnosis and management of the disease remains a major challenge. This study designed to discuss the epidemiology, pathogenesis and clinical appearances of MERS-CoV infections.

MATERIALS AND METHODS

We conducted a broad search of the English-language literature in "PubMed" "Medline" "Web of knowledge", "EMBASE" and "Google Scholar" World Health Organization-WHO" using the key words "Middle East Respiratory Syndrome", "MERS", "MERS-CoV" "Epidemiology" "Transmission" "Pathogenesis" "Clinical Characteristics". We reviewed the literature on epidemiology, pathogenesis and clinical appearances of MERS-CoV infection and the required information was documented.

RESULTS

The global prevalence of MERS-CoV infection from June 2012 to April 2018 is 2206 people. The number of cases reported from Saudi Arabia is 1831 (83%) with mortality rate of 787 (35.67%). The main clinical manifestations are fever, chills, generalized myalgia, cough, shortness of breath, nausea, vomiting and diarrhea. The age-allied prevalence of MERS-CoV was highest amongst elderly people with chronic debilitating diseases such as pulmonary diseases, end-stage renal illness, diabetes mellitus and malignancy.

CONCLUSIONS

MERS-CoV infection is an emerging global health concern, affected people in 27 countries in the various continents. MERS-CoV infection has been identified mainly in the Middle East, Europe, Africa, Asia and North America. Early detection and management of MERS-CoV infection is of critical importance to minimize the burden of the disease.

Global seasonal occurrence of middle east respiratory syndrome coronavirus (MERS-CoV) infection

OBJECTIVE

Middle East Respiratory Syndrome Coronavirus (MERS-CoV) is an evolving global health crisis. Despite recent efforts, there are numerous notable gaps in the understanding of MERS-CoV seasonal diversity. We aimed at investigating the global seasonal occurrence of Middle East Respiratory Syndrome coronavirus (MERS-CoV) outbreaks.

MATERIALS AND METHODS

We obtained the data on the prevalence and occurrence of Middle East Respiratory Syndrome Coronavirus (MERS-CoV) infection from the World Health Organization (WHO) for all the MERS cases reported from the various countries and their allied ministries. We also recorded the research documents published in various global scientific journals on the seasonal occurrence of MERS-CoV infection during the period 2012-2017.

RESULTS

Worldwide 2048 laboratory confirmed cases of MERS-CoV infection were reported from June 2012 to the Dec 2017. 1680 (82.03%) cases were from the Saudi Arabia and 368 (17.96%) cases were reported from the other countries of the world. The maximum number of cases reported in June was 474 (23.14%). 287 (14.01%) cases were reported from Saudi Arabia and remaining 187 (9.13%) cases were reported from all over the world. The number of cases reported from April to June was 396 (19.33%) while the cases encountered from October to December were 231 (11.27%).

CONCLUSIONS

The highest global seasonal occurrence of Middle East Respiratory Syndrome coronavirus-MERS-CoV outbreak cases were found in the month of June, while the lowest was found in the month of January during the period of 2012 to 2017. The pattern of MERS-CoV infections has been observed to have seasonal variations. It is suggested that the health officials should highlight the seasonal occurrence of MERS-CoV outbreak and take better preventive measures to minimize the disease burden nationally and globally.

CRISPR technology: new paradigm to target the infectious disease pathogens

OBJECTIVE

Infectious diseases are one of the prime causes of death worldwide. An innovative sequence specific editing technology "Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)" has been tested on a broad range of microorganisms to target and destroy invading foreign DNA to human cells or tissues. This study aimed to discuss the mechanism and therapeutic usage of CRISPR/Cas9 genome editing technology in the management of various infectious disease pathogens.

MATERIALS AND METHODS

We conducted a broad search of the English-language literature in "PubMed" using the search terms "CRISPR", "Cas-9", "Genome editing", "Gene therapy", "infectious disease pathogens". All the articles were reviewed and required information was recorded.

RESULTS

CRISPR technology is used to modify and modulate the gene expression in biomedical research and therapeutic development. This technology facilitates the understanding of fundamental biology and broadens the horizon of treatments of germ-laden conditions.

CONCLUSIONS

The applications of CRISPR technology are widely established in the diagnosis and treatment of various bacterial, viral, fungal and parasitic infectious diseases. CRISPR technology is a simple, efficient and tested on a broad range of microorganisms to rectify disease-associated genetic defects and destroy invading foreign DNA to human cells or tissues.

Encapsulation of Ibuprofen in CD-MOF and Related Bioavailability Studies

Although ibuprofen is one of the most widely used nonsteroidal anti-inflammatory drugs (NSAIDs), it exhibits poor solubility in aqueous and physiological environments as a free acid. In order to improve its oral bioavailability and rate of uptake, extensive research into the development of new formulations of ibuprofen has been undertaken, including the use of excipients as well as ibuprofen salts, such as ibuprofen lysinate and ibuprofen, sodium salt. The ultimate goals of these studies are to reduce the time required for maximum uptake of ibuprofen, as this period of time is directly proportional to the rate of onset of analgesic/anti-inflammatory effects, and to increase the half-life of the drug within the body; that is, the duration of action of the effects of the drug. Herein, we present a pharmaceutical cocrystal of ibuprofen and the biocompatible metal-organic framework called CD-MOF. This metal-organic framework (MOF) is based upon γ-cyclodextrin (γ-CD) tori that are coordinated to alkali metal cations (e.g., K⁺ ions) on both their primary and secondary faces in an alternating manner to form a porous framework built up from (γ-CD)₆ cubes. We show that ibuprofen can be incorporated within CD-MOF-1 either by (i) a crystallization process using the potassium salt of ibuprofen as the alkali cation source for production of the MOF or by (ii) absorption and deprotonation of the free-acid, leading to an uptake of 23-26 wt % of ibuprofen within the CD-MOF. In vitro viability studies revealed that the CD-MOF is inherently not affecting the viability of the cells with no IC₅₀ value determined up to a concentration of 100 μM. Bioavailability investigations were conducted on mice, and the ibuprofen/CD-MOF pharmaceutical cocrystal was compared to control samples of the potassium salt of ibuprofen in the presence and absence of γ-CD. From these animal studies, we observed that the ibuprofen/CD-MOF-1 cocrystal exhibits the same rapid uptake of ibuprofen as the ibuprofen potassium salt control sample with a peak plasma concentration observed within 20 min, and the cocrystal has the added benefit of a 100% longer half-life in blood plasma samples and is intrinsically less hygroscopic than the pure salt form.

Radically promoted formation of a molecular lasso

Two potential viologen-based molecular lasso precursors-both composed of a 4,4'-bipyridinium (BIPY2+) unit as part of a rope appended to a cyclobis(paraquat-p-phenylene) (CBPQT4+) loop-that have been designed to mimic the threading/unthreading motion of lasso peptides, have been synthesised and characterised. Solution and solid-state experiments reveal that, when the BIPY2+ unit in the rope and the CBPQT4+ loop are connected by a bulky linker, no lasso-like conformational transformation is observed between the different redox states on account of steric effects. In sharp contrast, when the linker size is small, the molecule can be switched between (i) a free rope-like conformation in its fully oxidised state and (ii) a self-entangled lasso-like conformation under reducing conditions employing either chemical or electrochemical stimuli: the BIPY˙+ unit in the rope resides inside the cavity of the CBPQT2(˙+) loop, forming a pseudo[1]rotaxane. The switching process is reversible and stereochemically unambiguous. This research shows how tiny structural differences can induce significantly different self-complexing properties and sheds light on designing functional artificial actuators.

Oligorotaxane Radicals under Orders

A strategy for creating foldameric oligorotaxanes composed of only positively charged components is reported. Threadlike components-namely oligoviologens-in which different numbers of 4,4'-bipyridinium (BIPY(2+)) subunits are linked by p-xylylene bridges, are shown to be capable of being threaded by cyclobis(paraquat-p-phenylene) (CBPQT(4+)) rings following the introduction of radical-pairing interactions under reducing conditions. UV/vis/NIR spectroscopic and electrochemical investigations suggest that the reduced oligopseudorotaxanes fold into highly ordered secondary structures as a result of the formation of BIPY(•+) radical cation pairs. Furthermore, by installing bulky stoppers at each end of the oligopseudorotaxanes by means of Cu-free alkyne-azide cycloadditions, their analogous oligorotaxanes, which retain the same stoichiometries as their progenitors, can be prepared. Solution-state studies of the oligorotaxanes indicate that their mechanically interlocked structures lead to the enforced interactions between the dumbbell and ring components, allowing them to fold (contract) in their reduced states and unfold (expand) in their fully oxidized states as a result of Coulombic repulsions. This electrochemically controlled reversible folding and unfolding process, during which the oligorotaxanes experience length contractions and expansions, is reminiscent of the mechanisms of actuation associated with muscle fibers.

CD-MOF: A Versatile Separation Medium

Porous metal-organic frameworks (MOFs) have been studied in the context of a wide variety of applications, particularly in relation to molecular storage and separation sciences. Recently, we reported a green, renewable framework material composed of γ-cyclodextrin (γ-CD) and alkali metal salts--namely, CD-MOF. This porous material has been shown to facilitate the separation of mixtures of alkylaromatic compounds, including the BTEX mixture (benzene, toluene, ethylbenzene, and the regioisomers of xylene), into their pure components, in both the liquid and gas phases, in an energy-efficient manner which could have implications for the petrochemical industry. Here, we report the ability of CD-MOF to separate a wide variety of mixtures, including ethylbenzene from styrene, haloaromatics, terpinenes, pinenes and other chiral compounds. CD-MOF retains saturated compounds to a greater extent than their unsaturated analogues. Also, the location of a double bond within a molecule influences its retention within the extended framework, as revealed in the case of the structural isomers of pinene and terpinine, where the isomers with exocyclic double bonds are more highly retained than those with endocyclic double bonds. The ability of CD-MOF to separate various mono- and disubstituted haloaromatic compounds appears to be controlled by both the size of the halogen substituents and the strength of the noncovalent bonding interactions between the analyte and the framework, an observation which has been confirmed by molecular simulations. Since CD-MOF is a homochiral framework, it is also able to resolve the enantiomers of chiral analytes, including those of limonene and 1-phenylethanol. These findings could lead to cheaper and easier-to-prepare stationary phases for HPLC separations when compared with other chiral stationary phases, such as CD-bonded silica particles.

Esterase- and pH-responsive poly(β-amino ester)-capped mesoporous silica nanoparticles for drug delivery

Gating of mesoporous silica nanoparticles (MSNs) with the stimuli-responsive poly(β-amino ester) has been achieved. This hybrid nanocarrier releases doxorubicin (DOX) under acidic conditions or in the presence of porcine liver esterase. The DOX loaded poly(β-amino ester)-capped MSNs reduce cell viability when tested on MDA-MB-231 human breast cancer cells.

Oxime ligation on the surface of mesoporous silica nanoparticles

A versatile surface-functionalization strategy applicable to mesoporous silica nanoparticles, which could potentially serve as drug delivery vehicles, is described that makes use of alkoxyamine tethers on the surface of the nanoparticles. A wide variety of carbonyl compounds can be attached readily to these tethers under the mild conditions of oxime ether formation, simply by incubating the chemically modified mesoporous silica nanoparticles with aldehydes or ketones in water.

Anticancer activity expressed by a library of 2,9-diazaperopyrenium dications

Polyaromatic compounds are well-known to intercalate DNA. Numerous anticancer chemotherapeutics have been developed upon the basis of this recognition motif. The compounds have been designed such that they interfere with the role of the topoisomerases, which control the topology of DNA during the cell-division cycle. Although many promising chemotherapeutics have been developed upon the basis of polyaromatic DNA intercalating systems, these candidates did not proceed past clinical trials on account of their dose-limiting toxicity. Herein, we discuss an alternative, water-soluble class of polyaromatic compounds, the 2,9-diazaperopyrenium dications, and report in vitro cell studies for a library of these dications. These investigations reveal that a number of 2,9-diazaperopyrenium dications show similar activities as doxorubicin toward a variety of cancer cell lines. Additionally, we report the solid-state structures of these dications, and we relate their tendency to aggregate in solution to their toxicity profiles. The addition of bulky substituents to these polyaromatic dications decreases their tendency to aggregate in solution. The derivative substituted with 2,6-diisopropylphenyl groups proved to be the most cytotoxic against the majority of the cell lines tested. In the solid state, the 2,6-diisopropylphenyl-functionalized derivative does not undergo π···π stacking, while in aqueous solution, dynamic light scattering reveals that this derivative forms very small (50-100 nm) aggregates, in contrast with the larger ones formed by dications with less bulky substituents. Alteration of the aromaticitiy in the terminal heterocycles of selected dications reveals a drastic change in the toxicity of these polyaromatic species toward specific cell lines.

Sugar and pH dual-responsive mesoporous silica nanocontainers based on competitive binding mechanisms

A sugar and pH dual-responsive controlled release system, which is highly specific towards molecular stimuli, has been developed based on the binding between catechol and boronic acid on a platform of mesoporous silica nanoparticles (MSNs). By grafting phenylboronic acid stalks onto the silica surface, catechol-containing β-cyclodextrins can be attached to the orifices of the MSNs' nanopores through formation of boronate esters which block access to the nanopores. These esters are stable enough to prevent cargo molecules from escaping. The boronate esters disassociate in the presence of sugars, enabling the molecule-specific controlled-release feature of this hybrid system. The rate of release has been found to be tunable by varying both the structures and the concentrations of sugars, as a result of the competitive binding nature associated with the mechanism of its operation. Acidification also induces the release of cargo molecules. Further investigations show that the presence of both a low pH and sugar molecules provides cooperative effects which together control the rate of release.

Assembly of supramolecular nanotubes from molecular triangles and 1,2-dihalohydrocarbons

Precise control of molecular assembly is a challenging goal facing supramolecular chemists. Herein, we report the highly specific assembly of a range of supramolecular nanotubes from the enantiomeric triangular naphthalenediimide-based macrocycles (RRRRRR)- and (SSSSSS)-NDI-Δ and a class of similar solvents, namely, the 1,2-dihalo-ethanes and -ethenes (DXEs). Three kinds of supramolecular nanotubes are formed from the columnar stacking of NDI-Δ units with a 60° mutual rotation angle as a result of cooperative [C-H···O] interactions, directing interactions of the [X···X]-bonded DXE chains inside the nanotubes and lateral [X···π] or [π···π] interactions. They include (i) semiflexible infinite nanotubes formed in the gel state from NDI-Δ and (E)-1,2-dichloroethene, (ii) rigid infinite nonhelical nanotubes produced in the solid state from NDI-Δ and BrCH2CH2Br, ClCH2CH2Br, and ClCH2CH2I, and (iii) a pair of rigid tetrameric, enantiomeric single-handed (P)- and (M)-helical nanotubes formed in the solid state from the corresponding (RRRRRR)- and (SSSSSS)-NDI-Δ with ClCH2CH2Cl. In case (i), only the electron-rich C═C double bond of (E)-1,2-dichloroethene facilitates the gelation of NDI-Δ. In cases (ii) and (iii), the lengths of anti-DXEs determine the translation of the chirality of NDI-Δ into the helicity of nanotubes. Only ClCH2CH2Cl induces single-handed helicity into the nanotubes. The subtle interplay of noncovalent bonding interactions, resulting from the tiny structural variations involving the DXE guests, is responsible for the diverse and highly specific assembly of NDI-Δ. This research highlights the critical role that guests play in constructing assembled superstructures of hosts and offers a novel approach to creating supramolecular nanotubes.