Stiffness measurement of nanosized liposomes using solid-state nanopore sensor with automated recapturing platform.

This paper describes a method to gauge the stiffness of nanosized liposomes - a nanoscale vesicle - using a custom-made recapture platform coupled to a solid-state nanopore sensor. The recapture platform electrically profiles a given liposome vesicle multiple times through automated reversal of the voltage polarity immediately following a translocation instance to re-translocate the same analyte through the nanopore - provides better statistical insight at the molecular level by analyzing the same particle multiple times compared to conventional nanopore platforms. The capture frequency depends on the applied voltage with lower voltages (i.e., 100 mV) permitting higher recapture instances than at higher voltages (>200 mV) since the probability of particles exiting the nanopore capture radius increases with voltage. The shape deformation was inferred by comparing the normalized relative current blockade ( ΔI/I0̂) at the two voltage polarities to that of a rigid particle, i.e., polystyrene beads. We found that liposomes deform to adopt a prolate shape at higher voltages. This platform can be further applied to investigate the stiffness of other types of soft matters, e.g., virus, exosomes, endosomes, and accelerate the potential studies in pharmaceutics for increasing the drug packing and unpacking mechanism by controlling the stiffness of the drug vesicles.

Low aspect ratio micropores for single-particle and single-cell analysis.

This paper describes microparticle and bacterial translocation studies using low aspect ratio solid-state micropores. Micropores, 5 µm in diameter, were fabricated in 200 nm thick free-standing silicon nitride membranes, resulting in pores with an extremely low aspect ratio, nominally 0.04. For microparticle translocation experiments, sulfonated polystyrene microparticles and magnetic microbeads in size range of 1-4 µm were used. Using the microparticle translocation characteristics, we find that particle translocations result in a change only in the pore's geometrical resistance while the access resistance remains constant. Furthermore, we demonstrate the ability of our micropore to probe high-resolution shape information of translocating analytes using concatenated magnetic microspheres. Distinct current drop peaks were observed for each microsphere of the multibead architecture. For bacterial translocation experiments, nonflagellated Escherichia coli (strain HCB 5) and wild type flagellated Salmonella typhimurium (strain SJW1103) were used. Distinct current signatures for the two bacteria were obtained and this difference in translocation behavior was attributed to different surface protein distributions on the bacteria. Our findings may help in developing low aspect ratio pores for high-resolution microparticle characterization and single-cell analysis.

Use of solid-state nanopores for sensing co-translocational deformation of nano-liposomes.

Membrane deformation of nano-vesicles is crucial in many cellular processes such as virus entry into the host cell, membrane fusion, and endo- and exocytosis; however, studying the deformation of sub-100 nm soft vesicles is very challenging using the conventional techniques. In this paper, we report detecting co-translocational deformation of individual 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) nano-liposomes using solid-state nanopores. Electrokinetic translocation through the nanopore caused the soft DOPC liposomes (85 nm diameter) to change their shape, which we attribute to the strong electric field strength and physical confinement inside the pore. The experiments were performed at varying transmembrane voltages and the deformation was observed to mount up with increasing applied voltage and followed an exponential trend. Numerical simulations were performed to simulate the concentrated electric field strength inside the nanopore and a field strength of 14 kV cm(-1) (at 600 mV applied voltage) was achieved at the pore center. The electric field strength inside the nanopore is much higher than the field strength known to cause deformation of 15-30 µm giant membrane vesicles. As a control, we also performed experiments with rigid polystyrene beads that did not show any deformation during translocation events, which further established our hypothesis of co-translocational deformation of liposomes. Our technique presents an innovative and high throughput means for investigating deformation behavior of soft nano-vesicles.

Comparison of Salivary and Serum Alkaline Phosphates Level and Lactate Dehydrogenase Levels in Patients with Tobacco Related Oral Lesions with Healthy Subjects - A Step Towards Early Diagnosis.

AIM: To evaluate and compare salivary and serum levels of Alkaline Phosphates and Lactate Dehydrogenase in patients without the habit of tobacco, in patients with the habit of tobacco, in patients with benign oral lesions and in patients with oral premalignant lesions and oral malignant lesions. MATERIAL AND METHODOLOGY: This study was comprised of 500 subjects, Group I: 100 healthy individuals without the habit of tobacco usage formed the control group. Group II: 100 patients with the habit of tobacco/ smoking consumption without any oral lesion. Group III: 100 patients with benign oral lesions. Group IV: 100 patients having the history of tobacco consumption and having apparent precancerous lesions like leukoplakia, erythroplakia. Group V:100  patients having frank oral cancer. The grade of dysplasia in these patients was statically correlated with the levels of serum and salivary ALP and LDH. RESULTS: This study revealed that there was high expression of both serum and salivary ALP and LDH  in group IV and Group V as compared with the other groups and mean difference showed a statistically significant p value of less than 0.01. This study revealed that the in group V, the highest level of serum and salivary ALP was found in those patients who were reported with poorly differentiated oral cancer. CONCLUSION: Both Alkaline phosphates and Lactate dehydrogenase could be considered a sensitive markers for the detection of dysplasia with already existing precancancerous and cancerous lesions.

The prevalence, radiographic appearance, and characteristics of zygomatic air cell defects (ZACDs) in symptomatic temporomandibular joint disorder patients in North Indian population.

PURPOSE: Although the incidence of zygomatic air cell defects (ZACDs) is significantly low in general population, still they pose as a risk factor during surgical procedures like eminectomies and eminoplasties because there is a risk of spread of infection intracranially. Furthermore, such procedures are more common in TMD patients. With this fact in mind, this study was designed to find out the prevalence, radiographic appearance, and characteristics of zygomatic air cell defects in diagnosed symptomatic temporomandibular joint disorder patients. METHOD: The study comprised of evaluation of panoramic radiographs of 70 temporomandibular joint disorder (TMD) patients in the age range of 18-30 years selected on the basis of Research Diagnostic Criteria (RDC/TMD). The radiographs were evaluated regarding the presence, variations, and characteristics of ZACDs. Groups were compared by χ (2) analysis. RESULTS: ZACDs were identified in 21 TMD subjects out of 70, giving an overall prevalence of 30 %. Out of 21 ZACDs, nine were in males (42.8 %) and 12 were in females (52.38 %). ZACDs were unilateral in ten TMD patients (47.61 %) and were bilateral in 11 patients (52.38 %). CONCLUSION: It can be concluded that the number of ZACDs is surprisingly more in diagnosed TMD patients. This strengthens the need for thorough preoperative imaging evaluation of ZACDs in such patients. Further longitudinal studies are required to find out the long-term effect of ZACDs on symptomatic as well as non-symptomatic TMD subjects. This may prove helpful to appreciate that whether ZACDs have any role in the development TMDs and vice versa. As with many TMD studies, caution should be exercised in interpreting these results until further studies have been carried out on this topic. Ideally, some prospective randomised evaluations with "hard" evidence of the diagnosis with MRI support.

Zygomatic air cell defect: a panoramic radiographic study of a North Indian population.

AIM: The aim of the present study was to determine the prevalence, radiographic appearance, and characteristics of zygomatic air cell defects (ZACD) in digital panoramic radiographs in a North Indian population. METHODS: The dental panoramic radiographs of 800 outpatients were selected from the records of the department, and were examined retrospectively to evaluate the variations and characteristics of ZACD. Groups were compared by χ(2) analysis for the presence of ZACD. RESULTS: ZACD were identified in 46 of 800 patients, giving an overall prevalence of 5.7%. Patients with ZACD were aged 4-60 years, with a mean age of 31.43 years. Most patients with ZACD were in their thirties. ZACD showed a no gender predilection; 29 of 46 patients were male (63.4%), and 17 were female (36.6%). Thirty cases (65.2%) of ZACD were unilateral, with 20 cases occurring on the right side. In 16 cases (34.8%), ZACD was bilateral. Forty four of the defects were unilocular, and two of the defects were multilocular. CONCLUSION: Digital panoramic radiographs are considered better than conventional panoramic radiographs in locating ZACD. Further, the presence of ZACD might be valuable for age estimations, to some extent. Further studies are required to investigate the pneumatization of articular eminence before puberty.