Nanodiamonds (NDs) are an emerging class of engineered nanomaterials that hold great promise for the next generation of bionanotechnological products to be used for drug and gene delivery, or for bio-imaging and biosensing. Previous studies have shown that upon their cellular uptake, NDs exhibit high biocompatibility in various in vitro and in vivo set-ups. Herein we hypothesized that the increased NDs biocompatibility is a result of minimum membrane perturbations and their reduced ability to induce disruption or damage during cellular translocation. Using multi-scale combinatorial approaches that simulate ND-membrane interactions, we correlated NDs real-time cellular uptake and kinetics with the ND-induced membrane fluctuations to derive energy requirements for the uptake to occur. Our discrete and real-time analyses showed that the majority of NDs internalization occurs within 2 h of cellular exposure, however, with no effects on cellular viability, proliferation or cellular behavior. Furthermore, our simulation analyses using coarse-grained models identified key changes in the energy profile, membrane deformation and recovery time, all functions of the average ND or ND-based agglomerate size. Understanding the mechanisms responsible for ND-cell membrane interactions could possibly advance their implementation in various biomedical applications.

Inorganic (ceramic) phosphors show distinct luminescence emission features upon infrared or ultraviolet excitation which in some cases depend on the history of the material. In particular, we observed the temporal luminescence behaviour of sodium yttrium fluoride (NaYF4) to change upon exposure to accelerated electrons. Hence, the material can be used as an optical dosimetry material for high-energy radiation. In this contribution we summarize our investigations of the optical property changes induced by electron beam treatment and present new data concerning the stability of the optical interrogation process. As a result, we find a broad dose range (0 to 150 kGy) to be addressable with NaYF4. The highest dose sensitivity occurs between 0 and 50 kGy which makes the material a promising candidate for optical dosimetry below 5 kGy, a dose range addressed so far only with more complex non-optical systems. Its high stability under ambient conditions further corroborates a potential application of the material for industrial dosimetry.

Optically active nanomaterials enable exciting novel applications of optical measurement technology such as gas sensing with nanoscale infrared antennas, dosimetry with ceramic phosphors, or molecular sensing and detection by means of nanostructured surfaces in general, to name a few only. Some techniques are still in their infancy, while others already led to industrially relevant applications. This article intentionally illustrates both ends of the readiness level scale to provide an idea of the bandwidth currently found in this field of research. On the one hand, surface-enhanced infrared spectroscopy and the fabrication of the necessary infrared nanoantennas as pursued in the group of the authors is described to give an example of an extremely promising, yet not market-ready optical nanosensor technology. On the other hand, the use of ceramic phosphors for radiation dose measurements is presented as a technique with a high technology readiness level and economically relevant application scenarios.

The Fraunhofer Institute for Ceramic Technologies and Systems, Branch Materials Diagnostics (IKTS-MD) covers also some fields of biosensing and nanotechnology, from basic research towards applications. This talk will especially address optically based methods for sensing applications: starting from analysis of the fractal dimension of time-resolved auto-fluorescence spectroscopy, to time-resolved luminescence measurements on upconversion phosphors for electron beam monitoring and last a refractive index sensing with a CCD chip technology based on localized SPR sensing. For all discussed methods the possible application will be discussed on examples of demonstrators in the fields of cancer diagnostics, medical surface sterilization process and biosensing.

We present our recent development concerning the evaluation of a low energy dose application to electron beam responding materials with a simple portable optical device. Electron beam irradiation is a promising option to sterilize sensitive and high performance products or surfaces at a low temperature and without moisture. Especially in the fields of the food industry and medicine, regulations regarding sterility are increasingly tightened. Because of this, a secure proof for electron-beam-assisted sterilization is required. However, no nondestructive and in situ method exists up until now. Our approach to provide a secure proof of sterilization is to place a suitable marker material based on rare-earth-doped phosphors inside or on the top of the packaging material of the respective product. Upon electron irradiation the marker material changes its luminescence properties as a function of the applied energy dose. We verified the energy dependence by means of time-resolved measurements of the luminescence decay of an upconversion phosphor with a portable optical device. In our experimental realization, short laser pulses in the near-infrared range are triggered by a microcontrol unit (MCU) and excite the marker material. The light emitted by the marker is collected in the range between 400 and 1100 nm via a silicon photodiode, processed by the MCU, and analyzed in a Labview program via a single-exponential fit. As a main result, we observe an increasing reduction of the luminescence lifetime with higher dose applications. (C) 2014 Society of Photo-Optical Instrumentation Engineers (SPIE)

Due to their outstanding properties nanodiamonds are a promising nanoscale material in various applications such as microelectronics, polishing, optical monitoring, medicine and biotechnology. Beyond the typical diamond characteristics like extreme hardness or high thermal conductivity, they have additional benefits as intrinsic fluorescence due to lattice defects without photobleaching, obtained during the high pressure high temperature process. Further the carbon surface and its various functional groups in consequence of the synthesis, facilitate additional chemical and biological modification. In this work we present our recent results on chemical modification of the nanodiamond surface with phosphate groups and their electrochemically assisted immobilization on titanium-based materials to increase adhesion at biomaterial surfaces. The starting material is detonation nanodiamond, which exhibits a heterogeneous surface due to the functional groups resulting from the nitrogen-rich explosives and the subsequent purification steps after detonation synthesis. Nanodiamond surfaces are chemically homogenized before proceeding with further functionalization. Suspensions of resulting surface-modified nanodiamonds are applied to the titanium alloy surfaces and the nanodiamonds subsequently fixed by electrochemical immobilization. Titanium and its alloys have been widely used in bone and dental implants for being a metal that is biocompatible with body tissues and able to bind with adjacent bone during healing. In order to improve titanium material properties towards biomedical applications the authors aim to increase adhesion to bone material by incorporating nanodiamonds into the implant surface, namely the anodically grown titanium dioxide layer. Differently functionalized nanodiamonds are characterized by infrared spectroscopy and the modified titanium alloys surfaces by scanning and transmission electron microscopy. The process described shows an adsorption and immobilization of modified nanodiamonds on titanium; where aminosilanized nanodiamonds coupled with O-phosphorylethanolamine show a homogeneous interaction with the titanium substrate.

In this contribution we provide an overview of current investigations on optically active particles (nanodiamonds, upconversion phospors) for biohybrid and sensing applications. Due to their outstanding properties nanodiamonds gain attention in various application fields such as microelectronics, optical monitoring, medicine, and biotechnology. Beyond the typical diamond properties such as high thermal conductivity and extreme hardness, the carbon surface and its various functional groups enable diverse chemical and biological surface functionalization.At Fraunhofer IKTS-MD we develop a customization of material surfaces via integration of chemically modi fied nanodiamonds at variable surfaces, e. g bone implants and pipelines. For the first purpose, nanodiamonds are covalently modified at their surface with amino or phosphate functionalities that are known to increase adhesion to bone or titanium alloys. The second type of surface is approached via mechanical implementation into coatings. Besides nanodiamonds, we also investigate the properties of upconversion phosphors. In our contribution we show how upconversion phosphors are used to verify sterilization processes via a change of optical properties due to sterilizing electron beam exposure.

In the last decades nanodiamonds have received special attention from the scientific community as a new carbon material with unique properties. Along with the macrosize diamond, those nanoparticles exhibit an exceptional hardness and sp 3 -core whereas, the size allows different applications. Among others they can be applied in new composites, lubrication oils, polishing and electronic materials, and drug delivery, biolabeling and bioimaging systems. To improve biocompatibility of diamond nanocrystals the surface functionalization is a favorable solution. The nanodiamonds the authors used were obtained by detonation synthesis and for this possess several functional groups on the surface. Further modifications require a homogeneous surface. In this approach a thermal methodology was used to remove the functional groups in order to produce an uniform carbon surface. The chosen biomolecules were phenylalanine, glutathione, biotin and O-phosphorylethanolamine to increase the biological suitability. The thermal annealing process was performed at three different temperatures: 750 °C, 900 °C and 1100 °C, under nitrogen flow to prevent oxidation. In the end of the procedure, samples were characterized by infrared spectroscopy, thermogravimetric analysis and transmission electron microscopy. Figure 1: Scheme of the thermal annealing processes used The results revealed a significant decrease in functional groups for all temperatures. At 1100 °C onion like carbon can be identified in our sample, proving of a successful graphitization of the nanodiamonds. For biofunctionalization different approaches were applied: 1) carboxylation and further peptide bonding; 2) hydroxylation, silanization and further peptide bonding; 3) click chemistry, as depicted in figure 2. Figure 2: Scheme from the functionalization of the thermal annealed nanodiamonds: Phephenylalanine; biotin; PEA Ophosphorylethanolamine acid and GSH glutathione. On the Click chemistry methodology isopentylnitrite was used as the activation agent for the integration of the biomolecules (phenylalanine, biotin, glutathione and O-phosphorylethanolamine) Success of the modification is verified by infrared spectroscopy and thermogravimetric analysis which evidence the success of the surface modification.

We present our recent investigations on time-resolved measurements of alterations in the temporal luminescence decay of upconversion phosphors induced by electron beam treatment. The latter is a promising alternative to low-temperature and dry sterilization of surfaces for sensitive packaging materials. Especially in the food and medical sector regulations concerning sterility are increasingly tightened. For this, a secure proof for electron-beam-assisted sterilization is required. However, no non-destructive and in situ method exists up to now.Our approach to provide a secure proof of sterilization is to place a suitable marker material based on rare-earth-doped phosphors inside or on top of the packaging material of the respective product. Upon electron irradiation the marker material changes its luminescent properties as a function of applied energy dose. We verified the energy dependence by means of time-resolved measurements of the luminescent decay of different upconversion materials.In our experimental realization short laser pulses in the near-infrared range excite the marker material. The emitted light is spectrally resolved in a monochromator, collected via a silicon photo diode, and analyzed with an oscilloscope. As the main results we observe a reduction of luminescence lifetime due to electron beam treatment dependent on the emission wavelength. Hence, the electron beam induces changes in the particles' up-and down-conversion properties from which the applied energy dose can be derived.

Secure proof of sterilization processes on packaging materials is an important issue in many economic sectors. In this context, electron beam sterilization is a highly effective low temperature technique. However, verifying the application of a sufficient electron dose is still difficult - especially on products with complex geometry. Here we report on an optical, hence fast and contactless approach which gives reliable evidence of a successful e-beam treatment. The technique is based on placing a suitable marker material (rare-earth based particles) inside or as a coating on the packaging material. By electron irradiation these particles change their optical properties and thus indicate the successful application of the electron beam.