In the US, central venous catheters (CVCs) have been used in roughly 5 million patients per annum. The use of these devices is for prolonged periods to deliver total parenteral nutrition, antibiotic therapy, and chemotherapy regimens.
Nevertheless, patients using CVCs often suffer from thrombosis and infection complications, which are associated with considerable morbidity and cost. According to a study, approximately 41% of cancer patients using CVCs demanded the removal of device before the course of treatment due to such complications.
The use of a poly-sulfobetaine to modify the internal and external surfaces of CVCs effectively reduced the attachment of proteins, microbes, and blood cells in in-vitro and short term in-vivo studies.
Attenuated total reflection Fourier transform infrared spectrometry (ATR FT-IR) is predominantly used for identifying the presence of the polymeric sulfobetaine surface modification.
The Harrick VideoMVP
The CVC surfaces, the inside lumen surfaces in particular, can have a surface area of <1 mm2 with complicated topographies. Therefore, a compact, extremely durable ATR FT-IR internal reflection element (IRE) in conjunction with the ability to precisely visualize the sample placement on the IRE in real time is essential (Figure 1).
These requirements can be readily met using the Harrick VideoMVP (Figure 2) with a diamond IRE and 250µm diameter sampling area.
Figure 1. Cross-section of a 5 French dual lumen CVC showing the approximate size of the inside surfaces requiring consistent and precise ATR FTIR.
Figure 2. The Harrick VideoMVP
A defined protocol sectioned surface modified CVCs to deliver a statistical sampling of both the internal and external surfaces of the devices. After placing the individual samples on the VideoMVP, the integrated video system was used to align the samples to the desired surface sample site.
The video image was observed and the applied force was monitored with the integrated force sensor to ensure constant and complete contact between the diamond IRE and the sample. The spectrometer equipped with a DTGS detector was set at a resolution of 4cm-1 to perform 32 spectral co- adds.
The algorithm described in Weinstock et al was used to monitor the spectral window of 881.8cm- 1 to 1845.6cm-1, yielding an estimated thickness of the surface modification at each sample site.
Experimental Results and Discussion
The estimated thickness range of the Sustain surface modification on the CVC substrate was 500-5000nm with ~1500nm median thickness and ±50nm precision (Figure 3).
Figure 3. ATR FT-IR Absorbance spectra of CVC septa with various thicknesses (0nm to >10,000nm) of poly-sulfobetaine modification.
From the results, it is evident that ATR FT-IR sampling of the different CVC surfaces can be reproducibly and rapidly performed using the Harrick VideoMVP.
As a result, manufacturers can set consistent boundaries for QC and improve the rate of analysis throughput to roughly 30min per CVC.
About Harrick Scientific Products, Inc.
Since its beginnings in 1969, Harrick Scientific has advanced the frontiers of optical spectroscopy through its innovations to transmission, internal reflection, external reflection, diffuse reflection, and emission spectroscopy. The president and founder of the corporation, Dr. N. J. Harrick, pioneered internal reflection spectroscopy and became the principal developer of this technique.
Harrick Scientific offers a large selection of standard and custom-built accessories for IR and UV-VIS spectrometers. Many of these attachments were originally forerunners in their field and their contemporary versions are considered industry standards. Harrick Scientific continues to introduce innovative new products. In addition to these state-of-the-art accessories, Harrick Scientific supplies a complete line of optical elements, including windows, ATR plates, prisms, and hemispheres.
This information has been sourced, reviewed and adapted from materials provided by Harrick Scientific Products, Inc.
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