Antibacterial and Osteoinductive Implant Surface Using Layer-by-Layer Assembly.

Osseointegration of dental, craniofacial, and orthopedic implants is critical for their long-term success. Multifunctional surface treatment of implants was found to significantly improve cell adhesion and induce osteogenic differentiation of dental-derived stem cells in vitro. Moreover, local and sustained release of antibiotics via nanolayers from the surface of implants can present unparalleled therapeutic benefits in implant dentistry. Here, we present a layer-by-layer surface treatment of titanium implants capable of incorporating BMP-2-mimicking short peptides and gentamicin to improve their osseointegration and antibacterial features. Additionally, instead of conventional surface treatments, we employed polydopamine coating before layer-by-layer assembly to initiate the formation of the nanolayers on rough titanium surfaces. Cytocompatibility analysis demonstrated that modifying the titanium implant surface with layer-by-layer assembly did not have adverse effects on cellular viability. The implemented nanoscale coating provided sustained release of osteoinductive peptides with an antibacterial drug. The surface-functionalized implants showed successful osteogenic differentiation of periodontal ligament stem cells and antimicrobial activity in vitro and increased osseointegration in a rodent animal model 4 wk postsurgery as compared with untreated implants. Altogether, our in vitro and in vivo studies suggest that this approach can be extended to other dental and orthopedic implants since this surface functionalization showed improved osseointegration and an enhanced success rate.

Flow mediated dilation with photoplethysmography as a substitute for ultrasonic imaging.

Flow mediated dilation (FMD) is a non-invasive method for endothelial function assessment providing an index extracted from ultrasonic B-mode images. Although utilized in the research community, the difficulty of its application and high cost of ultrasonic devices prevent it from being widely used in clinical settings. In this study we show that substituting the ultrasonic device with more easily handled and low cost photoplethysmography and electrocardiography is possible. We introduce new indices based on the photoplethysmogram (PPG) and electrocardiogram (ECG) and show that they are correlated with the ultrasound-based FMD Index. To this end, a conventional ultrasound FMD test was carried out whereas PPG and ECG were simultaneously recorded from 20 healthy volunteers (13 M, 7 F) in the age range of 23-32 years. Our results show a significant correlation between our proposed index and ultrasound FMD when using the ECG in conjunction with the PPG (R = 0.77, p < 0.000 01). Using the PPG alone produces a lower correlation (R = 0.72, p < 0.0001). Compared to conventional FMD, the proposed method is low cost and does not require any special operator skills. Hence it may be easily utilized as a screening tool in locations deprived of high-end ultrasound imaging devices.

Preconcentration of Zn2+ and Cu2+ ions from food and vegetable samples using modified activated carbon.

In this work, two N/S-containing chelating agents 2-(4-methoxybenzylideneamino)thiophenol (2-4-MBAT) and 2-(4-chlorobenzylideneamino) benzenethiol (2-4-CBABT) were synthesized as new sorbents and were used for preconcentration of Zn(2+) and Cu(2+) ions in food and vegetable samples. In the proposed procedure, the trace amount of Zn(2+) and Cu(2+) ions from 250 mL of sample solution at pH = 5.0 was preconcentrated by 1 g of activated carbon (AC) loaded with 15 mg of 2-4-MBAT and 2-4-CBABT separately. The breakthrough volumes (maximum sample volume that their metal ions quantitatively can be enriched) for solid-phase extraction (SPE) procedure based on the AC modified with 2-4-MBAT and 2-4-CBABT were 800 and 750 mL, respectively. The sorbed Zn(2+) and Cu(2+) ions were efficiently eluted by 8 mL of 4 mol L(-1) HNO(3) and preconcentration factor of 112.5 and 93.7 and experimental enhancement factor of 30 and 35 ions were obtained for Zn(2+) and Cu(2+), respectively. The application of this enrichment procedure allowed the extraction of trace metal ions with recoveries exceeding of 90%.

The application of empirical mode decomposition for the enhancement of cardiotocograph signals.

Cardiotocograph (CTG) is widely used in everyday clinical practice for fetal surveillance, where it is used to record fetal heart rate (FHR) and uterine activity (UA). These two biosignals can be used for antepartum and intrapartum fetal monitoring and are, in fact, nonlinear and non-stationary. CTG recordings are often corrupted by artifacts such as missing beats in FHR, high-frequency noise in FHR and UA signals. In this paper, an empirical mode decomposition (EMD) method is applied on CTG signals. A recursive algorithm is first utilized to eliminate missing beats. High-frequency noise is reduced using EMD followed by the partial reconstruction (PAR) method, where the noise order is identified by a statistical method. The obtained signal enhancement from the proposed method is validated by comparing the resulting traces with the output obtained by applying classical signal processing methods such as Butterworth low-pass filtering, linear interpolation and a moving average filter on 12 CTG signals. Three obstetricians evaluated all 12 sets of traces and rated the proposed method, on average, 3.8 out of 5 on a scale of 1(lowest) to 5 (highest).

Finger photoplethysmogram pulse amplitude changes induced by flow-mediated dilation.

This study was conducted to investigate the utility and efficacy of finger photoplethysmogram pulse amplitude (PPG-AC) in comparison with the standard Doppler ultrasound in assessing an endothelial function via flow-mediated dilation (FMD). High-resolution B-mode scanning of the right brachial artery (BA) of 31 healthy subjects aged 39.7 +/- 11.3 (range 22-64) years and 52 risk subjects aged 47.7 +/- 10.8 (range 30-65) years were performed before and after 4 min of upper arm occlusion. Concurrent with the ultrasound measurement (where color Doppler imaging was used to enhance arterial boundary detection), PPG signals were recorded from both index fingers for cross evaluation and comparison. Our results show that the finger PPG-AC exhibits a similar response to that of the well-known BA dilation: following the release of pressure (cuff around the BA), the PPG-AC increases abruptly before slowly decreasing toward the baseline. The peak PPG-AC is reached significantly faster than the peak FMD measured by ultrasound among healthy and risk groups (P < 0.001). The proposed technique using a finger photoplethysmogram can be applied in a rapid and non-invasive assessment of peripheral vascular functions as an alternative low-cost and less operator-dependent tool compared to ultrasound.

Dual-channel photoplethysmography synchronization using a Barker sequence.

A Barker sequence is employed for the synchronization of two photoplethysmogram (PPG) channels. The correctness of this technique is demonstrated by recording a PPG signal, injecting a Barker sequence at the start of this trace and producing a delayed version of it. After preprocessing, cross-correlation techniques are utilized for accurate time alignment of the two traces. The algorithm can correct for any time misalignment as long as the synchronization sequence appears on both channels.