Implementation of 3D printing technologies to electrochemical and optical biosensors developed for biomedical and pharmaceutical analysis.

Three-dimensional (3D) printing technology has been applied in many areas. In recent years, new generation biosensors have been emerged with the progress on 3D printing technology (3DPT). Especially in the development of optical and electrochemical biosensors, 3DPT provides many advantages such as low cost, easy to manufacturing, being disposable and allow point of care testing. In this review, recent trends in the development of 3DPT based electrochemical and optical biosensors with their applications in the field of biomedical and pharmaceutical are examined. In addition, the advantages, disadvantages and future opportunities of 3DPT are discussed.

Diagnostic kit based on halloysite nanoclay-ionic liquid nanocomposite modified electrode for electrochemical determination of cancer biomarker.

Nucleic acid hybridization is occurred between the selective single-stranded nucleic acid sequence and its target sequence, which is one of the essential procedure for electrochemical detection of nucleic acid. microRNA-21 (miRNA-21) is known as a biomarker in various cancers. The determination of miRNA-21 was attained through by hybridization of inosine substituted miRNA-21 specific DNA probe (Pinosine) with its target miRNA-21. In this study, the surface of pencil graphite electrode (PGE) was firstly modified with halloysite nanoclay-ionic liquid (HNT/IL) nanocomposite. The characterization of surface was performed by Scanning Electron Microscope (SEM) images and Energy Dispersive X-Ray Analysis (EDX) analysis, and the differences at surface modifications were also shown by electrochemical methods with electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). For sensitive and selective determination of miRNA-21, Pinosine and target miRNA concentration, immobilization and hybridization time were optimized by using HNT/IL modified PGE in combination with differential pulse voltammetry (DPV). The detection limit was achieved as 0.17 µg/mL (equals to 23.69 nM) in the linear range of 0.25-2 µg/mL miRNA-21. The selectivity of voltammetric method based on HNT/IL-PGE developed for miRNA-21 was examined in the presence of mismatch (MM) and non-complementary (NC) sequences. Because miRNA-21 is over-expressed in cancer cells, it has been tested in total RNA samples isolated from cancer cell line (breast cancer cell line, MCF-7). In the total RNA samples obtained from MCF-7, the detection limit was calculated as 0.28 µg/mL in the linear range of 1-4 µg/mL. Besides, the healthy cell line (human embryonic kidney cell line, HEK-293) was used as a control group and the results obtained by MCF-7 total RNA samples were compared to the results using HEK-293 total RNA samples in terms of miRNA-21 level.

Six-minute stepper test for evaluating functional exercise capacity in patients with sarcoidosis.

BACKGROUND: Researchers and clinicians may benefit from alternative tests that do not require large physical spaces or corridors for simply evaluating functional exercise capacity in the clinical practice. OBJECTIVE: Aim of this study was to investigate whether six-minute stepper test (6MST) is a valid tool for measuring functional exercise capacity in patients with sarcoidosis. METHODS: Thirty-six patients with sarcoidosis and 18 healthy controls were evaluated with 6MST and six-minute walk test (6MWT). Patients performed 6MST twice. Cardiovascular and symptom responses to tests including heart rate, blood pressure, SpO2, levels of dyspnea and fatigue were recorded. RESULTS: Receiver operating characteristic (ROC) curve analysis revealed an area under the ROC curve of 0.74 for 6MST in identifying the patients and controls, indicating acceptable discriminative ability. Patients performed significantly worse in 6MST compared to controls (277±54 vs 349±87 steps; p<0.001). 6MST was able to explain 66% of variance in 6MWT (p<0.001), and there was a strong relationship between 6MWT and 6MST (r = 0.812). SpO2 responses to tests were similar, however, 6MST generated more severe heart rate, dyspnea and fatigue responses. Intraclass correlation coefficient calculated for initial and retest scores of 6MST was 0.990, indicating excellent test-retest reliability. However, there was a systematical improvement (∼4%) in retest 6MST scores. CONCLUSIONS: 6MST is a valid and reliable alternative test for measuring functional exercise capacity in sarcoidosis. 6MST may also help better testing the upper limits of cardiac system and physical endurance as it is more physically demanding than 6MWT.

Electrochemical DNA biosensors developed for the monitoring of biointeractions with drugs: a review.

The interaction of drugs with DNA is important for the discovery of novel drug molecules and for understanding the therapeutic effects of drugs as well as the monitoring of side effects. For this reason, many studies have been carried out to investigate the interactions of drugs with nucleic acids. In recent years, a large number of studies have been performed to electrochemically detect drug-DNA interactions. The fast, sensitive, and accurate results of electrochemical techniques have resulted in a leading role for their implementation in this field. By means of electrochemical techniques, it is possible not only to demonstrate drug-DNA interactions but also to quantitatively analyze drugs. In this context, electrochemical biosensors for drug-DNA interactions have been examined under different headings including anticancer, antiviral, antibiotic, and central nervous system drugs as well as DNA-targeted drugs. An overview of the studies related to electrochemical DNA biosensors developed for the detection of drug-DNA interactions that were reported in the last two decades in the literature is presented herein along with their applications and they are discussed together with their future perspectives.

Impedimetric Detection Based on Label-Free Immunoassay Developed for Targeting Spike S1 Protein of SARS-CoV-2.

After the COVID-19 pandemic started all over the world, great importance was placed on the development of sensitive and selective bioanalytical assays for the rapid detection of the highly pathogenic SARS-CoV-2 virus causing COVID-19 disease. In this present work, an impedimetric immunosensor was developed and applied for rapid, reliable, sensitive and selective detection of the SARS-CoV-2 S1 protein. To detect the SARS-CoV-2 virus, targeting of the spike S1 protein was achieved herein by using S1 protein-specific capture antibody (Cab-S1) immobilized screen-printed electrode (SPE) in combination with the electrochemical impedance spectroscopy (EIS) technique. With the impedimetric immunosensor, the detection limit for S1 protein in buffer medium was found to be 0.23 ng/mL (equal to 23.92 amol in 8 µL sample) in the linear concentration range of S1 protein from 0.5 to 10 ng/mL. In the artificial saliva medium, it was found to be 0.09 ng/mL (equals to 9.36 amol in 8 µL sample) in the linear concentration range of S1 protein between 0.1 and 1 ng/mL. The selectivity of the impedimetric immunosensor toward S1 protein was tested against influenza hemagglutinin antigen (HA) in the buffer medium as well as in artificial saliva.

Amperometric immunosensor developed for sensitive detection of SARS-CoV-2 spike S1 protein in combined with portable device.

In this present study, an amperometric immunosensor was developed based on disposable screen-printed carbon electrode (SPCE) for specific and sensitive detection of SARS-CoV-2 S1 protein. Anti-SARS-CoV-2 S1 monoclonal antibody was firstly immobilized onto the electrode surface. Then, the sandwich complex was formed by addition of S1 protein, secondary antibody and HRP-IgG, respectively. Chronoamperometry measurements were done in the presence of TMB mediator and the detection of SARS-CoV-2 S1 protein was performed by using 10 µL sample. The limit of detection (LOD) was found to be 0.19 ng/mL (equals to 24.7 amol in 10 µL sample) in the linear range of 0.5-10 ng/mL obtained in buffer medium. The applicability of this assay was investigated in the linear range of 0.5-3 ng/mL S1 protein in artificial saliva medium with the LOD as 0.13 ng/mL (equals to 16.9 amol in 10 µL sample). The selectivity study was examined in the presence of Hemagglutinin antigen (HA) in both mediums; buffer and artificial saliva while resulting with the successful discrimination between S1 protein and HA. The one of ultimate goals of our study is to present the possible implementation of this assay to point of care (POC) analysis. Under this aim, this assay was performed in combination with a portable device that is the commercial electrochemical analyzer. Amperometric detection of S1 protein in the range of 0.5-5 ng/mL was also successfully performed in artificial saliva medium with a resulting LOD as 0.15 ng/mL (equals to 19.5 amol in 10 µL sample). In addition, a selectivity study was similarly carried out by portable device.

Voltammetric detection of miRNA hybridization based on electroactive indicator-cobalt phenanthroline.

The indicator-based nucleic acid detection protocol is one of the major approaches to monitor the sequence-selective nucleic acid hybridization-mediated recognition events in biochemical analysis. The metal complex, cobalt phenanthroline, [Co(phen)33+], which is one of the electroactive indicators, interacts more with double stranded nucleic acids via intercalation. Thus, this interaction permits an increase at the electrochemical signal of [Co(phen)33+]. In our study, the interaction of metal complex, [Co(phen)33+] with nucleic acids was examined using pencil graphite electrodes (PGEs) in combination with differential pulse voltammetry (DPV) technique. The voltammetric detection of miRNA-34a was investigated based on the changes at the electrochemical signal of [Co(phen)33+] under optimized experimental conditions; such as accumulation potentialof metal complex and DNA probe concentration, hybridization time, target miRNA concentration. Furthermore, the selectivity of electrochemical miRNA-34a biosensor was studied in contrast to different miRNAs. The applicability of indicator-based biosensor specific to miRNA-34a was also presented by using total RNA samples.

Shear Bond Strength of Intraoral Laser Welding and its Effect on Intrapulpal Temperature Rise in Primary Teeth: An in Vitro Study.

OBJECTIVE: This study compared the shear bond strength (SBS) of conventional welding (CW) and intraoral laser welding (LW) on fixed space maintainers (SMs), and investigated the intrapulpal temperature change (ITC) during LW. BACKGROUND DATA: Lasers have been used for intraoral welding. MATERIALS AND METHODS: The SBS test used 26 molar bands divided into two groups, CW and LW. Stainless steel wires were welded to the middle of the buccal and lingual aspects of all the bands, using an Nd:YAG laser for the LW group and silver solder and flux soldering media for the CW group. The samples, fixed to acrylic resin blocks, were subjected to shear testing. In the ITC test, 25 exfoliated primary second molar teeth were used to adapt molar bands. J-type thermocouple wire was positioned in the pulp chamber. ITCs were determined during Nd:YAG laser welding of stainless steel wires to the bands. Mann-Whitney U test was used to determine differences in SBS between the groups. ITCs were analyzed by paired t test. RESULTS: The SBS between groups showed significant differences (LW: 489.47 ± 135.70; CW: 49.71 ± 17.76; p < 0.001). The mean ITC during LW was 3.64 ± 0.79 (min: 2.4; max: 5.10). None of the samples' ITCs exceeded the critical threshold value (5.5 °C). CONCLUSIONS: LW obtained a higher-strength joint than CW. ITCs during LW do not present a thermal risk to primary teeth. The intraoral use of LW for SMs in primary teeth is recommended in terms of strength and ITCs.

Fracture strength of restorations in proximal cavities of primary molars.

This study evaluated the fracture strength of various restorative materials for primary molars in dovetail and box-only class II cavity designs. Eighty extracted noncarious human primary molars were used. The teeth were randomly divided into two groups for either dovetail or box-only preparations. The teeth were then divided into four subgroups for each restorative material: glass ionomer cement (GIC), resin-modified glass ionomer cement (RMGIC), compomer, and composite. The restorations were tested for fracture strength. The loads at fracture and fracture mode were recorded and a scanning electron microscopy analysis was performed to observe the micromorphology of the borders between the teeth and the materials. The nonparametric Kruskal-Wallis and Mann-Whitney U-tests were used. Although there were significant differences between the restorative materials (p < 0.05), there were no differences between the fracture strength of the box-only and the dovetail cavity designs in any of the groups (p > 0.05) except the composite group. The fracture strength of the compomer and composite groups was significantly higher than that of the GIC and RMGIC groups (p < 0.05). A class II cavity could be selected as dovetail or box-only and compomer and composite are more resistant to fracture than GIC and RMGIC.

Color stability and surface roughness of polished anterior restorative materials.

The purpose of this study was to investigate the effects of different finishing-polishing techniques on the color stability and surface roughness of various anterior restorative materials after staining. A composite, a compomer, and a resin-modified glass ionomer were used to prepare 120 specimens. Specimens were divided into subgroups: polishing discs, liquid polishing material, aluminium oxidebonded discs, and control. The specimens were stained in a coffee solution. Color parameters (L*a*b*) and surface roughness before and after staining were measured. The color was affected by the material type (p<0.05) and finishing-polishing systems (p<0.05). The composite showed the highest color stability; however, the color differences of all groups were visible even to the nonskilled operator. The Ra values did not significantly change after staining for any of the restorative groups (p>0.05). The finishing-polishing systems had an effect on color after storing in staining solution.

Evaluation of formocresol, calcium hydroxide, ferric sulfate, and MTA primary molar pulpotomies.

OBJECTIVE: The aim of this study is to evaluate four different pulpotomy medicaments in primary molars. MATERIALS AND METHODS: A total of 147 primary molars with deep caries were treated with four different pulpotomy medicaments (FC: formocresol, FS: ferric sulfate, CH: calcium hydroxide, and MTA: mineral trioxide aggregate) in this study. The criteria for tooth selection for inclusion were no clinical and radiographic evidence of pulp pathology. During 30 months of follow-up at 6-month intervals, clinical and radiographic success and failures were recorded. The differences between the groups were statistically analyzed using the Chi-square test and Kaplan-Meier analysis. RESULTS: At 30 months, clinical success rates were 100%, 95.2%, 96.4%, and 85% in the FC, FS, MTA, and CH groups, respectively. In radiographic analysis, the MTA group had the highest (96.4%), and the CH group had the lowest success rate (85%). There were no clinical and radiographic differences between materials (P > 0.05). CONCLUSIONS: Although there were no differences between materials, only in the CH group did three teeth require extraction due to further clinical symptoms of radiographic failures during the 30-month follow-up period. None of the failed teeth in the other groups required extraction during the 30-month follow-up period.

Effects of different polishing methods on color stability of resin composites after accelerated aging.

The purpose of this study was to evaluate the effect of polishing procedures on the color stability of different types of composites after aging. Forty disk-shaped specimens (Ø10×2 mm) were prepared for each composite resin type (an ormocer, a packable, a nanohybrid, and a microhybrid) for a total of 160 specimens. Each composite group was divided into four subgroups according to polishing method (n=10): control (no finishing and polishing), polishing disk, polishing wheel, and glaze material. Color parameters (L*, a*, and b*) and surface roughness were measured before and after accelerated aging. Of the polishing methods, glazed specimens showed the lowest color change (∆E*), ∆L*, and ∆b* values (p<0.05). Of the composite resins, the microhybrid composite showed the lowest ∆E* value, whereas the ormocer showed the highest (p<0.05). For all composite types, the surface roughness of their control groups decreased after aging (p<0.05). In conclusion, all composite resins showed color changes after accelerated aging, with the use of glaze material resulting in the lowest color change.

The effect of fissure sealants on the values of two different caries detection devices.

OBJECTIVE: The aim of this in vitro study was to evaluate the effects of clear and opaque fissure sealants on readings of laser fluorescence (LF) and light-emitting diode (LED) based caries detection devices. BACKGROUND DATA: When planning patient care, the practitioner needs to consider any changes in the status of the sealed surface for the long-term success of the sealant. As visual inspection is difficult to perform on sealed surfaces, adjunct diagnostic methods must be used to improve follow-up assessments and increase the accuracy of caries diagnosis. METHODS: Forty-six freshly extracted permanent human molars were selected and divided into two groups. Each group was treated with a different sealant (clear and opaque). The teeth were measured twice by two blinded observers using an LF-based and an LED-based device before and after sealing. The data were analyzed using Wilcoxon's matched-pairs signed-rank test and a paired t-test. Cohen's κ and the intraclass correlation coefficient were used to examine intra- and inter-examiner repeatability. RESULTS: The values of the LED device were significantly higher after the application of the opaque sealant, but there was no statistically significant difference after the application of the clear sealant (p=0.15). The LF-based device readings were also significantly lower after both the clear and the opaque sealant applications (p<0.001). CONCLUSIONS: The readings from the LF-based device were affected by both sealants. The readings from the LED-based device were affected by the opaque sealant but not by the clear sealant.

Reattachment of fractured maxillary incisors using fiber-reinforced post: Two case reports.

OBJECTIVE: The reattachment of the crown fragment to a fractured tooth is a conservative treatment that should be considered for young patients with crown-root fractures to the maxillary incisors if the subgingival fracture can be exposed to provide isolation. Gingivectomy, the surgical or orthodontic extrusion of the apical fragment is necessary to expose the subgingival fracture. This report demonstrates the treatment of two cases with the combination of gingivectomy or resective osseous surgery, reattachment of coronal fracture and fiber-reinforced polymer posts and shows three years long term follow-up. Subgingivally extended crown-root fractures of maxillary incisors were restored with a combination of chemically cured resin material, light cured resin material and polyethylene fiber. CONCLUSION: Within the limitations of this case report, it was demonstrated that reattachment of tooth fragments can successfully benefit periodontal health, aesthetic needs and normal functioning after three years.

TaqMan Real-Time Quantification of Epstein-Barr Virus in Severe Early Childhood Caries.

OBJECTIVES: Early childhood caries (ECC) has several risk factors and it is important stressful/painful events of childhood and immunosuppression may occur during this unique rampant caries pattern. The changes in the host immune competence by compromised cellular immune system functions can activate Epstein Barr virus (EBV). The objective of this study was to determine whether the supragingival plaque samples of severe-ECC (S-ECC) patients harbor more EBV load than the non-carious healthy children by quantitative TaqMan Real-Time polymerase chain reaction (PCR). METHODS: Sixty subjects, including 30 S-ECC patients as well as age and gender matched 30 caries-free patients were studied. The supragingival plaque samples were collected from patients by brushing their teeth for 1 minute and the toothbrush was washed in 1 ml of sterile deionized water. After viral DNA extraction, TaqMan real-time PCR assay was used to quantify EBV DNA. Dental treatments were completed for all S-ECC patients and they were called for routine controls. Only 10 treated S-ECC patients were come to the 3(rd) months' control and post-treatment viral sampling was made in the same manner. RESULTS: EBV DNA was detected 16 of 30 S-ECC patients and 6 of the healthy controls (P<.001). There was no relationship between baseline and post-treatment samples of 10 treated S-ECC patients. CONCLUSIONS: The results of the study suggest that oro-dental hygiene motives of S-ECC patients might be important contributory factor for S-ECC and EBV would not be involved in the etiopathogenesis of ECC.