Direct Thermal Growth of Gold Nanopearls on 3D Interweaved Hydrophobic Fibers as Ultrasensitive Portable SERS Substrates for Clinical Applications.

Surface-enhanced Raman spectroscopy (SERS)-based biosensors have attracted much attention for their label-free detection, ultrahigh sensitivity, and unique molecular fingerprinting. In this study, a wafer-scale, ultrasensitive, highly uniform, paper-based, portable SERS detection platform featuring abundant and dense gold nanopearls with narrow gap distances, are prepared and deposited directly onto ultralow-surface-energy fluorosilane-modified cellulose fibers through simple thermal evaporation by delicately manipulating the atom diffusion behavior. The as-designed paper-based SERS substrate exhibits an extremely high Raman enhancement factor (3.9 × 1011 ), detectability at sub-femtomolar concentrations (single-molecule level) and great signal reproductivity (relative standard deviation: 3.97%), even when operated with a portable 785-nm Raman spectrometer. This system is used for fingerprinting identification of 12 diverse analytes, including clinical medicines (cefazolin, chloramphenicol, levetiracetam, nicotine), pesticides (thiram, paraquat, carbaryl, chlorpyrifos), environmental carcinogens (benzo[a]pyrene, benzo[g,h,i]perylene), and illegal drugs (methamphetamine, mephedrone). The lowest detection concentrations reach the sub-ppb level, highlighted by a low of 16.2 ppq for nicotine. This system appears suitable for clinical applications in, for example, i) therapeutic drug monitoring for individualized medication adjustment and ii) ultra-early diagnosis for pesticide intoxication. Accordingly, such scalable, portable and ultrasensitive fibrous SERS substrates open up new opportunities for practical on-site detection in biofluid analysis, point-of-care diagnostics and precision medicine.

Process and formulation characterizations of the thermal adhesion granulation (TAG) process for improving granular properties.

In this study, we demonstrate the feasibility of using the thermal adhesion granulation (TAG) method to improve granular properties for preparing highly compressible excipients as direct tabletting aids. The TAG method subjects a mixture containing excipients, such as microcrystalline cellulose (MCC), lactose, starch, or dibasic calcium phosphate (DCP), under closed conditions with a low moisture content and low content of polyvinyl pyrrolidone (PVP) as a binder, to heating during mixing by tumble rotation to produce highly compressible granules. Results demonstrated that a closed system is more efficient than an open system at such a low moisture content, and both water and ethanol were able to fulfill the role of a granulation liquid, but water was more appropriate than ethanol for successfully producing granules suitable for use as direct tabletting aids by the TAG method. It was also found that a 5% moisture content in the powder mixture containing MCC and PVP is optimal in the TAG process to produce granules with the desired characteristics for pharmaceutical applications. On the contrary, increasing the moisture content led to further decreases in the mean size and deterioration of the flowability. It was further demonstrated that the TAG process is able to imbue these commonly used diluents with more-desirable physical characteristics of granules for direct tabletting, enabling the processing of these commonly used diluents with 50% PVP into directly compressible matrix materials.