Near-field optics uniquely addresses problems of x, y and z resolution by spatially confining the effect of a light source to nanometric domains. The problems in using far-field optics (conventional optical imaging through a lens) to achieve nanometric spatial resolution are formidable. Near-field optics serves a bridging role in biology between optical imaging and scanned probe microscopy. The integration of near-field and scanned probe imaging with far-field optics thus holds promise for solving the so-called inverse problem of optical imaging.

Many peptide nanostructures, self-assembled from chemically synthesized biomolecules, have drawn much attention in the fi eld of nanotechnology due to their physical, chemical, and biological properties, which make them promising candidates for applications in bionanomedicine, [ 1 ] bionanotechnology, [ 2,3 ] electronics, [ 4,5 ] optics, [ 6 ] energy storage, [ 7,8 ] etc. Some of these properties, such as ferro-and piezoelectricity observed in diphenylalanine nanotubes (FF-PNT) [ 9 ] are directly related to the nanocrystalline structural asymmetry of the elementary building blocks comprising these supramolecular materials. [ 6,10 ] One basic physical effect that depends on both the crystalline symmetry and the electronic properties of dielectric materials is second harmonic generation (SHG). SHG is observed only in crystals with no center of symmetry [ 11 ] and is related to ferroelectric phenomena together with linear electrooptical and piezoelectric effects. Ferroelectric effects have been observed in many biological materials such as plants, animals, and human tissues (amino acids, pineal gland of brain, skin, tendon, etc.). [ 12 ] Today, the SHG effect is also exploited in optical microscopy, especially in medical and biological research. [ 13 ] It allows the detection of two-photon emission from biomaterials and biopolymers [ 14 ] lacking a center of symmetry. The effect has been used with quantitative metrics for diagnosing a wide range of diseases. [ 15 ] Recently, second-order responses have also been found in bioinspired aromatic FF-PNT with hexagonal space group P6 1 using nonlinear optical microscopy. [ 16 ] Both the elementary crystalline symmetry and the electronic structure of bioinspired peptide nanostructures can be significantly changed by deep reconstruction process, such as phase transformation at a nanoscale level, which results in the disappearance of an SHG response. [ 17 ] Another method to modulate these fundamental properties is to use different solvents, [18][19][20][21] which strongly infl uence the self-assembly process and defi ne peptide nanostructures' morphologies. Modifi cation of the physical properties in peptide nanomaterials is a new way to fabricate basic nanoscale units for future bottom-up nanotechnologies. [ 6 ] Bioinspired peptide nanostructures, much like other organic nanostructures, [ 22,23 ] have ultra-small sizes and are easily produced by a rapid self-assembly fabrication process. All these properties make them favorable for implementation in diverse applications, and especially in biophotonics devices.In this work, we have studied the SHG effect in bioorganic peptide nanostructures of different morphologies and symmetries, such as nanotubes, nanofi bers, nanobelts, and nanospheres. These nanostructures were self-assembled in different solvents from peptide precursors with a variable number of A nonlinear optical effect of a second harmonic generation (SHG) was fi rst observed in quartz and then found in many inorganic materials that have an asymmetric crystalline s...

The major advantages of "naked DNA gene therapy" are its simplicity and a low or negligible immune response. Gene delivery by DNA electroporation (EP) involves injection of DNA and the application of a brief electric pulse to enhance cellular permeability. Although EP is an efficient gene transduction technique in rodents, it requires much higher voltages (>500 V) in larger animals, and hence, in practice it would be hazardous for human patients, as it would cause serious tissue damage. To overcome the obstacles associated with EP-mediated gene delivery in vivo, we developed a new method of gene transduction that uses laser energy. The femtosecond infrared titanium sapphire laser beam was developed specifically for enhancing in vivo gene delivery without risks of tissue damage. System optimization revealed that injection of 10 micro g naked DNA into the tibial muscle of mice followed by application of the laser beam for 5 s, focused to 2 mm depth upon an area of 95 x 95 micro m(2), resulted in the highest intensity and duration of gene expression with no histological or biochemical evidence of muscle damage. We assessed the potential clinical application of LBGT technology by using it to transfer the murine erythropoietin (mEpo) gene into mice. LBGT-mediated mEpo gene delivery resulted in elevated (>22%) hematocrit levels that were sustained for 8 weeks. Gene expression following LBGT was detected for >100 days. Hence, LBGT is a simple, safe, effective, and reproducible method for therapeutic gene delivery with significant clinical potential.

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Bacteriorhodopsin's photocycle is initiated by the retinal chromophore light absorption. It has usually been assumed that light primarily isomerizes a retinal double bond which in turn induces protein conformational alterations and biological activity. We have studied several artificial pigments derived from retinal analogues tailored to substantially reduce the light-induced chromophore polarization. The lack of chromophore polarization was reflected in an undetectable second harmonic generation (SHG) signal. It was revealed that these artificial pigments did not exhibit any detectable light-induced photocycle nor light acceleration of the hydroxylamine-bleaching reaction. We suggest that light-induced retinal polarization triggers protein polarization which controls the course of the isomerization reaction by determining the relative efficiency of forward versus back-branching processes.