Collagen membrane functionalized with magnesium oxide via room-temperature atomic layer deposition promotes osteopromotive and antimicrobial properties

Artificial bone grafting materials such as collagen are gaining interest due to the ease of production and implantation. However, collagen must be supplemented with additional coating materials for improved osteointegration. Here, we report room-temperature atomic layer deposition (ALD) of MgO, a novel method to coat collagen membranes with MgO. Characterization techniques such as X-ray photoelectron spectroscopy, Raman spectroscopy, and electron beam dispersion mapping confirm the chemical nature of the film. Scanning electron and atomic force microscopies show the surface topography and morphology of the collagen fibers were not altered during the ALD of MgO. Slow release of magnesium ions promotes bone growth, and we show the deposited MgO film leaches trace amounts of Mg when incubated in phosphate-buffered saline at 37 °C. The coated collagen membrane had a superhydrophilic surface immediately after the deposition of MgO. The film was not toxic to human cells and demonstrated antibacterial properties against bacterial biofilms. Furthermore, in vivo studies performed on calvaria rats showed MgO-coated membranes (200 and 500 ALD) elicit a higher inflammatory response, leading to an increase in angiogenesis and a greater bone formation, mainly for Col-MgO500, compared to uncoated collagen. Based on the characterization of the MgO film and in vitro and in vivo data, the MgO-coated collagen membranes are excellent candidates for guided bone regeneration.

Is atomic layer deposition of silver possible on N95 masks?

Due to the COVID19 outbreak, there has been increasing interest in tailoring, modifying and improving conventional personal protective equipment to increase their service life and make them more effective against viruses and bacteria. Here, atomic layer deposition (ALD) was used to functionalize the filter of N95 mask with nano-islands of silver. X-ray photoelectron spectroscopy and x-ray absorption fine structure were used for ALD silver characterization; microbiological assay was conducted to study the effectiveness of the deposited silver against the air-borne pathogen Staphylococcus aureus (S. aureus). Results showed that silver ALD successfully functionalized the N95 mask at 90 and 120 °C for two different numbers of ALD cycles (1100 and 1500 cycles). The deposited silver nano-islands were stable on the N95 filter media against washing. The leaching of silver nano-islands was studied using inductively coupled plasma mass spectrometry of phosphate-buffered saline solution after soaking the mask in it over predetermined times. <9% of Ag was removed after a maximum time of 4 h that was investigated. Antimicrobial tests showed that for samples functionalized with 1100 ALD cycles of Ag, 76% reduction in S. aureus colony-forming units content was observed after 24 h of biofilm development on the mask surfaces.

Hybrid Pixel-Waveform (HPWF) Enabled CdTe Detectors for Small Animal Gamma-Ray Imaging Applications

This paper presents the design and preliminary evaluation of small-pixel CdTe gamma ray detectors equipped with a hybrid pixel-waveform (HPWF) readout system for gamma ray imaging applications with additional discussion on CZT due to its similarity. The HPWF readout system utilizes a pixelated anode readout circuitry which is designed to only provide the pixel address. This readout circuitry works in coincidence with a high-speed digitizer to sample the cathode waveform which provides the energy, timing, and depth-of-interaction (DOI) information. This work focuses on the developed and experimentally evaluated prototype HPWF-CdTe detectors with a custom CMOS pixel-ASIC to readout small anode pixels of 350 μm in size, and a discrete waveform sampling circuitry to digitize the signal waveform induced on the large cathode. The intrinsic timing, energy, and spatial resolution were experimentally evaluated in this paper in conjunction with methods for depth of interaction (DOI) partitioning of the CdTe crystal. While the experimental studies discussed in this paper are primarily for evaluating HPWF detectors for small animal PET imaging, these detectors could find their applications for ultrahigh-resolution SPECT and other imaging modalities.

Inguinal hernia is not a sign of colon cancer: results of a prospective screening trial

BACKGROUND

It has been suggested that patients with an inguinal hernia harbour an increased risk for colorectal cancer.

METHODS

In a prospective clinical trial, we compared the prevalence of colonic neoplasms in 100 cases with inguinal hernia and 100 controls without inguinal hernia. The number, size, histology type, and the location of all colorectal lesions found during a screening flexible sigmoidoscopy were recorded.

RESULTS

Not a single case of colorectal cancer was detected in the patients with inguinal hernia pending surgical repair. In the asymptomatic control subjects, one Dukes A and one Dukes B1 colon cancer were detected. Polypectomy was performed in 15% and 17% of the case and control subjects, respectively. During a 5-year period following the initial screening procedure, none of the case or control subjects was diagnosed with colon cancer.

CONCLUSIONS

The decision for or against performing an endoscopic procedure in a patient with inguinal hernia should be guided by the general principles of screening for colorectal cancer. The mere presence of an inguinal hernia does not automatically increase the risk of colorectal cancer.

Quantitation of urinary hydroxypyridinium cross-links from collagen by high-performance liquid chromatography

Pyridinoline and deoxypyridinoline are intermolecular cross-links in mature collagen in bone and cartilage. The urinary excretion of the two compounds correlates well to bone turnover. A fast, sensitive, and accurate isocratic ion-pairing reverse-phase high-performance liquid chromatography method for measurement of pyridinoline and deoxypyridinoline in urine has been established. Intra- and inter-assay precision were 5-7% and 12-14%, respectively. Recovery for pyridinoline was 97.4% and for deoxypyridinoline 94.3%. The detection limit was 0.4 pmol. Pyridinoline:creatinine and deoxypyridinoline: creatinine ratios in healthy subjects, were 38.8 nmol:mmol and 13.0 nmol:mmol, respectively. Increased values of both cross-links were observed in children, in the age group 20-29 in both sexes, and in post-menopausal women.

Semiautomated homogeneous enzyme immunoassay of total serum thyroxine with a kinetic analyzer

A new semiautomatic procedure for determination of total serum thyroxine was adapted to a kinetic analyzer, LKB 2086 Mark II. The ABA thyroxine assay kit was used, and although the assay procedure was modified, the advantage of small reagent volumes, short measuring times, and automation were retained. The results were analyzed off-line with a programmable desk-top calculator. The method has a precision of 7% (CV) and a sensitivity of 8 nmol/L. Values in sera from 64 patients analyzed by enzyme immunoassay and by radioimmunoassay correlated well (r = 0.975). One kit contains enough reagents for 500 assays, and an operator could do 25 samples (i.e., 64 assays) in about 4 h.

Semiautomated homogeneous enzyme immunoassay of total serum thyroxine with a kinetic analyzer

A new semiautomatic procedure for determination of total serum thyroxine was adapted to a kinetic analyzer, LKB 2086 Mark II. The ABA thyroxine assay kit was used, and although the assay procedure was modified, the advantage of small reagent volumes, short measuring times, and automation were retained. The results were analyzed off-line with a programmable desk-top calculator. The method has a precision of 7% (CV) and a sensitivity of 8 nmol/L. Values in sera from 64 patients analyzed by enzyme immunoassay and by radioimmunoassay correlated well (r = 0.975). One kit contains enough reagents for 500 assays, and an operator could do 25 samples (i.e., 64 assays) in about 4 h.

Semiautomated homogeneous enzyme immunoassay of total serum thyroxine with a kinetic analyzer

A new semiautomatic procedure for determination of total serum thyroxine was adapted to a kinetic analyzer, LKB 2086 Mark II. The ABA thyroxine assay kit was used, and although the assay procedure was modified, the advantage of small reagent volumes, short measuring times, and automation were retained. The results were analyzed off-line with a programmable desk-top calculator. The method has a precision of 7% (CV) and a sensitivity of 8 nmol/L. Values in sera from 64 patients analyzed by enzyme immunoassay and by radioimmunoassay correlated well (r = 0.975). One kit contains enough reagents for 500 assays, and an operator could do 25 samples (i.e., 64 assays) in about 4 h.